Remove always defined FEATURE_CORESYSTEM

59 files changed, 12 insertions, 1672 deletions

diff --git a/src/ToolBox/SOS/Strike/util.cpp b/src/ToolBox/SOS/Strike/util.cpp
index b6336fb143..90574fc6f0 100644
--- a/src/ToolBox/SOS/Strike/util.cpp
+++ b/src/ToolBox/SOS/Strike/util.cpp
@@ -4791,13 +4791,7 @@ HRESULT InitCorDebugInterface()
     // SOS now has a statically linked version of the loader code that is normally found in mscoree/mscoreei.dll
     // Its not much code and takes a big step towards 0 install dependencies
     // Need to pick the appropriate SKU of CLR to detect
-#if defined(FEATURE_CORESYSTEM)
     GUID skuId = CLR_ID_ONECORE_CLR;
-#elif defined(FEATURE_CORECLR)
-    GUID skuId = CLR_ID_CORECLR;
-#else
-    GUID skuId = CLR_ID_V4_DESKTOP;
-#endif
     CLRDebuggingImpl* pDebuggingImpl = new CLRDebuggingImpl(skuId);
     hr = pDebuggingImpl->QueryInterface(IID_ICLRDebugging, (LPVOID *)&pClrDebugging);
     if (FAILED(hr))
diff --git a/src/binder/applicationcontext.cpp b/src/binder/applicationcontext.cpp
index e5c3025787..2d41dc6e16 100644
--- a/src/binder/applicationcontext.cpp
+++ b/src/binder/applicationcontext.cpp
@@ -12,9 +12,6 @@
 //
 // ============================================================
 
-#ifndef FEATURE_CORESYSTEM
-#define DISABLE_BINDER_DEBUG_LOGGING
-#endif
 
 #include "applicationcontext.hpp"
 #include "stringarraylist.h"
diff --git a/src/classlibnative/nls/nlsinfo.cpp b/src/classlibnative/nls/nlsinfo.cpp
index 0e034c4a0c..d24e4b02d6 100644
--- a/src/classlibnative/nls/nlsinfo.cpp
+++ b/src/classlibnative/nls/nlsinfo.cpp
@@ -2369,26 +2369,6 @@ BOOL QCALLTYPE COMNlsInfo::InternalTryFindStringOrdinalIgnoreCase(
     else
 #endif
     {
-#ifndef FEATURE_CORESYSTEM
-        // kernel function pointer
-        typedef int (WINAPI *PFNFindStringOrdinal)(DWORD, LPCWSTR, INT, LPCWSTR, INT, BOOL);
-        static PFNFindStringOrdinal FindStringOrdinal = NULL;
-
-        // initizalize kernel32!FindStringOrdinal
-        if (FindStringOrdinal == NULL)
-        {
-            PFNFindStringOrdinal result  = NULL;
-
-            HMODULE hMod=WszGetModuleHandle(WINDOWS_KERNEL32_DLLNAME_W);
-            if(hMod != NULL)
-                result=(PFNFindStringOrdinal)GetProcAddress(hMod,"FindStringOrdinal");
-            
-            FindStringOrdinal = (result != NULL) ? result : (PFNFindStringOrdinal)-1;
-        }
-
-        // call into the kernel
-        if (FindStringOrdinal != (PFNFindStringOrdinal)-1)
-#endif
         {
             *foundIndex = FindStringOrdinal(
                 dwFindNLSStringFlags,
diff --git a/src/debug/daccess/daccess.cpp b/src/debug/daccess/daccess.cpp
index 69167ab07e..c5781ae54d 100644
--- a/src/debug/daccess/daccess.cpp
+++ b/src/debug/daccess/daccess.cpp
@@ -6573,7 +6573,6 @@ bool ClrDataAccess::GetILImageInfoFromNgenPEFile(PEFile *peFile,
     return true;
 }
 
-#if defined(FEATURE_CORESYSTEM)
 /* static */
 // We extract "ni.dll or .ni.winmd" from the NGEM image name to obtain the IL image name.
 // In the end we add given ilExtension.
@@ -6632,7 +6631,6 @@ bool ClrDataAccess::GetILImageNameFromNgenImage( LPCWSTR ilExtension,
 
     return false;
 }
-#endif // FEATURE_CORESYSTEM
 
 void *
 ClrDataAccess::GetMetaDataFromHost(PEFile* peFile,
@@ -6742,7 +6740,6 @@ ClrDataAccess::GetMetaDataFromHost(PEFile* peFile,
             goto ErrExit;
         }
         
-#if defined(FEATURE_CORESYSTEM)
         const WCHAR* ilExtension[] = {W("dll"), W("winmd")};
         WCHAR ngenImageName[MAX_LONGPATH] = {0};
         if (wcscpy_s(ngenImageName, NumItems(ngenImageName), uniPath) != 0)
@@ -6760,7 +6757,6 @@ ClrDataAccess::GetMetaDataFromHost(PEFile* peFile,
             {
                 goto ErrExit;
             }
-#endif//FEATURE_CORESYSTEM
 
             // RVA size in ngen image and IL image is the same. Because the only
             // different is in RVA. That is 4 bytes column fixed.
@@ -6793,13 +6789,11 @@ ClrDataAccess::GetMetaDataFromHost(PEFile* peFile,
                     (BYTE*)buffer,
                     NULL);
             }
-#if defined(FEATURE_CORESYSTEM)
             if (SUCCEEDED(hr))
             {
                 break;
             }
         }
-#endif // FEATURE_CORESYSTEM
     }
 
     if (FAILED(hr))
@@ -6989,10 +6983,8 @@ bool ClrDataAccess::TargetConsistencyAssertsEnabled()
     return m_fEnableTargetConsistencyAsserts; 
 }
 
-#ifdef FEATURE_CORESYSTEM
 #define ctime_s _ctime32_s
 #define time_t __time32_t
-#endif
 
 // 
 // VerifyDlls - Validate that the mscorwks in the target matches this version of mscordacwks
@@ -7532,11 +7524,7 @@ BOOL OutOfProcessExceptionEventGetProcessIdAndThreadId(HANDLE hProcess, HANDLE h
     *pPId = (DWORD)hProcess;
     *pThreadId = (DWORD)hThread;
 #else
-#if !defined(FEATURE_CORESYSTEM)
-    HMODULE hKernel32 = WszGetModuleHandle(W("kernel32.dll"));
-#else
 	HMODULE hKernel32 = WszGetModuleHandle(W("api-ms-win-core-processthreads-l1-1-1.dll"));
-#endif
     if (hKernel32 == NULL)
     {
         return FALSE;
diff --git a/src/debug/daccess/dacimpl.h b/src/debug/daccess/dacimpl.h
index 635be80232..91722f5d1f 100644
--- a/src/debug/daccess/dacimpl.h
+++ b/src/debug/daccess/dacimpl.h
@@ -14,14 +14,11 @@
 #ifndef __DACIMPL_H__
 #define __DACIMPL_H__
 
-#if defined(_TARGET_ARM_) || defined(FEATURE_CORESYSTEM) // @ARMTODO: STL breaks the build with current VC headers
 //---------------------------------------------------------------------------------------
 // Setting DAC_HASHTABLE tells the DAC to use the hand rolled hashtable for
 // storing code:DAC_INSTANCE .  Otherwise, the DAC uses the STL unordered_map to.
 
 #define DAC_HASHTABLE
-#endif // _TARGET_ARM_|| FEATURE_CORESYSTEM
-
 #ifndef DAC_HASHTABLE
 #pragma push_macro("return")
 #undef return
@@ -1482,11 +1479,9 @@ public:
                                              DWORD &dwSize,
                                              __out_ecount(cchPath) LPWSTR wszPath,
                                              const DWORD cchPath);
-#if defined(FEATURE_CORESYSTEM)
     static bool GetILImageNameFromNgenImage(LPCWSTR ilExtension,
                                             __out_ecount(cchFilePath) LPWSTR wszFilePath,
                                             const DWORD cchFilePath);
-#endif // FEATURE_CORESYSTEM
 };
 
 extern ClrDataAccess* g_dacImpl;
diff --git a/src/debug/daccess/nidump.cpp b/src/debug/daccess/nidump.cpp
index 23e76c4fe4..7a2a62f3ad 100644
--- a/src/debug/daccess/nidump.cpp
+++ b/src/debug/daccess/nidump.cpp
@@ -15,9 +15,6 @@
 #include <comcallablewrapper.h>
 #include <gcdump.h>
 
-#if !defined(FEATURE_CORESYSTEM)
-#include <algorithm>
-#endif
 
 #include <constrainedexecutionregion.h>
 
@@ -31,11 +28,6 @@
 
 #include <mdfileformat.h>
 
-#if !defined(FEATURE_CORESYSTEM)
-#include <cassert>
-#undef _ASSERTE
-#define _ASSERTE(x) assert(x)
-#endif
 
 #include <compile.h>
 
@@ -6073,16 +6065,6 @@ void NativeImageDumper::DumpTypes(PTR_Module module)
         //there may be duplicates in the list.  Remove them before moving on.
         COUNT_T mtCount = m_discoveredMTs.GetCount();
 
-#if !defined(FEATURE_CORESYSTEM) // no STL right now
-        std::sort(&*m_discoveredMTs.Begin(),
-                  (&*m_discoveredMTs.Begin())
-                  + (m_discoveredMTs.End() - m_discoveredMTs.Begin()));
-        PTR_MethodTable* newEnd = std::unique(&*m_discoveredMTs.Begin(),
-                                              (&*m_discoveredMTs.Begin())
-                                              + (m_discoveredMTs.End()
-                                                 - m_discoveredMTs.Begin()));
-        mtCount = (COUNT_T)(newEnd - &*m_discoveredMTs.Begin());
-#endif
 
         DisplayStartArray( "MethodTables", NULL, METHODTABLES );
         for(COUNT_T i = 0; i < mtCount; ++i )
@@ -6098,15 +6080,6 @@ void NativeImageDumper::DumpTypes(PTR_Module module)
         DisplayStartArray( "MethodTableSlotChunks", NULL, METHODTABLES );
         {
             COUNT_T slotChunkCount = m_discoveredSlotChunks.GetCount();
-#if !defined(FEATURE_CORESYSTEM) // no STL right now
-            std::sort(&*m_discoveredSlotChunks.Begin(),
-                      (&*m_discoveredSlotChunks.Begin())
-                      + (m_discoveredSlotChunks.End() - m_discoveredSlotChunks.Begin()));
-            SlotChunk *newEndChunks = std::unique(&*m_discoveredSlotChunks.Begin(),
-                                              (&*m_discoveredSlotChunks.Begin())
-                                              + (m_discoveredSlotChunks.End() - m_discoveredSlotChunks.Begin()));
-            slotChunkCount = (COUNT_T)(newEndChunks - &*m_discoveredSlotChunks.Begin());
-#endif
             
             for (COUNT_T i = 0; i < slotChunkCount; ++i)
             {
@@ -6121,16 +6094,6 @@ void NativeImageDumper::DumpTypes(PTR_Module module)
 
         //there may be duplicates in the list.  Remove them before moving on.
         COUNT_T clazzCount = m_discoveredClasses.GetCount();
-#if !defined(FEATURE_CORESYSTEM) // no STL right now
-        std::sort(&*m_discoveredClasses.Begin(),
-                  (&*m_discoveredClasses.Begin())
-                  + (m_discoveredClasses.End() - m_discoveredClasses.Begin()));
-        PTR_MethodTable * newEndClazz = std::unique(&*m_discoveredClasses.Begin(),
-                                               (&*m_discoveredClasses.Begin())
-                                               +(m_discoveredClasses.End()
-                                                 -m_discoveredClasses.Begin()));
-        clazzCount = (COUNT_T)(newEndClazz - &*m_discoveredClasses.Begin());
-#endif
 
         for(COUNT_T i = 0; i < clazzCount; ++i )
         {
@@ -6149,17 +6112,6 @@ void NativeImageDumper::DumpTypes(PTR_Module module)
 
         //there may be duplicates in the list.  Remove them before moving on.
         COUNT_T tdCount = m_discoveredTypeDescs.GetCount();
-#if !defined(FEATURE_CORESYSTEM) // no STL right now
-        std::sort(&*m_discoveredTypeDescs.Begin(),
-                  (&*m_discoveredTypeDescs.Begin())
-                  + (m_discoveredTypeDescs.End()
-                     - m_discoveredTypeDescs.Begin()));
-        PTR_TypeDesc* newEndTD = std::unique(&*m_discoveredTypeDescs.Begin(),
-                                             (&*m_discoveredTypeDescs.Begin())
-                                             +(m_discoveredTypeDescs.End()
-                                               -m_discoveredTypeDescs.Begin()));
-        tdCount = (COUNT_T)(newEndTD - &*m_discoveredTypeDescs.Begin());
-#endif
 
         for(COUNT_T i = 0; i < tdCount; ++i )
         {
diff --git a/src/debug/di/cordb.cpp b/src/debug/di/cordb.cpp
index 497225fd67..7f8c087399 100644
--- a/src/debug/di/cordb.cpp
+++ b/src/debug/di/cordb.cpp
@@ -86,15 +86,6 @@ HINSTANCE       g_hInst;                // Instance handle to this piece of code
 //*****************************************************************************
 STDAPI CreateCordbObject(int iDebuggerVersion, IUnknown ** ppCordb)
 {
-#if defined(FEATURE_CORECLR) && !defined(FEATURE_DBGIPC_TRANSPORT_DI) && !defined(FEATURE_CORESYSTEM)
-    // This API should not be called for Windows CoreCLR unless we are doing interop-debugging
-    // (which is only supported internally).  Use code:CoreCLRCreateCordbObject instead.
-    if (CLRConfig::GetConfigValue(CLRConfig::INTERNAL_DbgEnableMixedModeDebugging) == 0)
-    {
-        _ASSERTE(!"Deprecated entry point CreateCordbObject() is called on Windows CoreCLR\n");
-        return E_NOTIMPL;
-    }
-#endif // FEATURE_CORECLR && !FEATURE_DBGIPC_TRANSPORT_DI
 
     if (ppCordb == NULL)
     {
diff --git a/src/debug/di/module.cpp b/src/debug/di/module.cpp
index 36cc6f5f9e..46487b92c9 100644
--- a/src/debug/di/module.cpp
+++ b/src/debug/di/module.cpp
@@ -5153,7 +5153,7 @@ HRESULT CordbNativeCode::GetReturnValueLiveOffsetImpl(Instantiation *currentInst
 
                 int skipBytes = 0;
 
-#if defined(DBG_TARGET_X86) && defined(FEATURE_CORESYSTEM)
+#if defined(DBG_TARGET_X86)
                 // Skip nop sleds on x86 coresystem.  The JIT adds these instructions as a security measure,
                 // and incorrectly reports to us the wrong offset of the call instruction.
                 const BYTE nop_opcode = 0x90;
diff --git a/src/debug/di/process.cpp b/src/debug/di/process.cpp
index a5496eee54..53fb2ca0f6 100644
--- a/src/debug/di/process.cpp
+++ b/src/debug/di/process.cpp
@@ -381,7 +381,6 @@ IMDInternalImport * CordbProcess::LookupMetaDataFromDebugger(
 
             WCHAR *mutableFilePath = (WCHAR *)filePath;
 
-#if defined(FEATURE_CORESYSTEM)
             size_t pathLen = wcslen(mutableFilePath);
 
             const wchar_t *nidll = W(".ni.dll");
@@ -403,7 +402,6 @@ IMDInternalImport * CordbProcess::LookupMetaDataFromDebugger(
             {
                 wcscpy_s(mutableFilePath+pathLen-winmdLen, winmdLen, W(".winmd"));
             }
-#endif//FEATURE_CORESYSTEM
 
             ALLOW_DATATARGET_MISSING_MEMORY(
                 pMDII = LookupMetaDataFromDebuggerForSingleFile(pModule, mutableFilePath, dwImageTimeStamp, dwImageSize);
@@ -7605,27 +7603,7 @@ HRESULT CordbProcess::GetRuntimeOffsets()
 
 
     {
-#if !defined FEATURE_CORESYSTEM
-        // kernel32!OpenThread does not exist on all platforms (missing on Win98).
-        // So we need to delay load it.
-        typedef HANDLE (WINAPI *FPOPENTHREAD)(DWORD dwDesiredAccess,
-                                              BOOL bInheritHandle,
-                                              DWORD dwThreadId);
-
-
-
-        HMODULE mod = WszGetModuleHandle(W("kernel32.dll"));
-
-        _ASSERTE(mod != NULL); // can't fail since Kernel32.dll is already loaded.
-
-        const FPOPENTHREAD pfnOpenThread = (FPOPENTHREAD)GetProcAddress(mod, "OpenThread");
-
-        if (pfnOpenThread != NULL)
-        {
-            m_hHelperThread = pfnOpenThread(SYNCHRONIZE, FALSE, dwHelperTid);
-            CONSISTENCY_CHECK_MSGF(m_hHelperThread != NULL, ("Failed to get helper-thread handle. tid=0x%x\n", dwHelperTid));
-        }
-#elif FEATURE_PAL
+#if FEATURE_PAL
         m_hHelperThread = NULL; //RS is supposed to be able to live without a helper thread handle.
 #else
         m_hHelperThread = OpenThread(SYNCHRONIZE, FALSE, dwHelperTid);
@@ -9798,13 +9776,11 @@ HRESULT CordbProcess::EnsureClrInstanceIdSet()
     if (m_clrInstanceId == 0)
     {
 
-#ifdef FEATURE_CORESYSTEM
         if(m_cordb->GetTargetCLR() != 0)
         {
             m_clrInstanceId = PTR_TO_CORDB_ADDRESS(m_cordb->GetTargetCLR());
             return S_OK;
         }
-#endif
 
         // The only case in which we're allowed to request the "default" CLR instance
         // ID is when we're running in V2 mode.  In V3, the client is required to pass
@@ -14947,17 +14923,6 @@ HRESULT CordbProcess::IsReadyForDetach()
     // and hard detach failures (after which the process object is neutered).
     if (m_pShim != NULL)
     {
-#if !defined(FEATURE_CORESYSTEM) // CORESYSTEM TODO
-        HModuleHolder hKernel32;
-        hKernel32 = WszLoadLibrary(W("kernel32"));
-        if (hKernel32 == NULL)
-            return HRESULT_FROM_GetLastError();
-        typedef BOOL (*DebugActiveProcessStopSig) (DWORD);
-        DebugActiveProcessStopSig pDebugActiveProcessStop = 
-            reinterpret_cast<DebugActiveProcessStopSig>(GetProcAddress(hKernel32, "DebugActiveProcessStop"));
-        if (pDebugActiveProcessStop == NULL)
-            return COR_E_PLATFORMNOTSUPPORTED;
-#endif
     }    
 
     return S_OK;
diff --git a/src/debug/di/publish.cpp b/src/debug/di/publish.cpp
index 888988a10f..a7e2ebb9c2 100644
--- a/src/debug/di/publish.cpp
+++ b/src/debug/di/publish.cpp
@@ -44,19 +44,6 @@ BOOL GetAllProcessesInSystem(DWORD *ProcessId,
 {    
     HandleHolder hSnapshotHolder;
 
-#if !defined(FEATURE_CORESYSTEM)
-    // Load the dll "kernel32.dll".
-    HModuleHolder hDll = WszLoadLibrary(W("kernel32"));
-    _ASSERTE(hDll != NULL);
-
-    if (hDll == NULL)
-    {
-        LOG((LF_CORDB, LL_INFO1000,
-                "Unable to load the dll for enumerating processes. "
-                "LoadLibrary (kernel32.dll) failed.\n"));
-        return FALSE;
-    }
-#else
 	// Load the dll "api-ms-win-obsolete-kernel32-l1-1-0.dll".
     HModuleHolder hDll = WszLoadLibrary(W("api-ms-win-obsolete-kernel32-l1-1-0.dll"));
     _ASSERTE(hDll != NULL);
@@ -68,7 +55,6 @@ BOOL GetAllProcessesInSystem(DWORD *ProcessId,
                 "LoadLibrary (api-ms-win-obsolete-kernel32-l1-1-0.dll) failed.\n"));
         return FALSE;
     }
-#endif
   
     
     // Create the Process' Snapshot
@@ -183,11 +169,7 @@ CorpubPublish::CorpubPublish()
 {
     // Try to get psapi!GetModuleFileNameExW once, and then every process object can use it.
     // If we can't get it, then we'll fallback to getting information from the IPC block.
-#if !defined(FEATURE_CORESYSTEM)
-    m_hPSAPIdll = WszLoadLibrary(W("psapi.dll"));
-#else
 	m_hPSAPIdll = WszLoadLibrary(W("api-ms-win-obsolete-psapi-l1-1-0.dll"));
-#endif
 
     if (m_hPSAPIdll != NULL)
     {
diff --git a/src/debug/di/rsmain.cpp b/src/debug/di/rsmain.cpp
index 0f5778789f..6e0ccf8872 100644
--- a/src/debug/di/rsmain.cpp
+++ b/src/debug/di/rsmain.cpp
@@ -864,10 +864,8 @@ Cordb::Cordb(CorDebugInterfaceVersion iDebuggerVersion)
     m_processes(11),
     m_initialized(false),
     m_debuggerSpecifiedVersion(iDebuggerVersion)
-#ifdef FEATURE_CORESYSTEM
     ,
     m_targetCLR(0)
-#endif
 {
     g_pRSDebuggingInfo->m_Cordb = this;
 
@@ -1314,9 +1312,7 @@ HRESULT Cordb::SetTargetCLR(HMODULE hmodTargetCLR)
     if (m_initialized)
         return E_FAIL;
 
-#ifdef FEATURE_CORESYSTEM
     m_targetCLR = hmodTargetCLR;
-#endif
 
     // @REVIEW: are we happy with this workaround?  It allows us to use the existing
     // infrastructure for instance name decoration, but it really doesn't fit
@@ -1425,14 +1421,6 @@ bool Cordb::IsInteropDebuggingSupported()
     // ICorDebug::SetUnmanagedHandler for details.
 #ifdef FEATURE_INTEROP_DEBUGGING
 
-#if defined(FEATURE_CORECLR) && !defined(FEATURE_CORESYSTEM)
-    // Interop debugging is only supported internally on CoreCLR.
-    // Check if the special reg key is set.  If not, then we don't allow interop debugging.
-    if (CLRConfig::GetConfigValue(CLRConfig::INTERNAL_DbgEnableMixedModeDebugging) == 0)
-    {
-        return false;
-    }
-#endif // FEATURE_CORECLR
 
     return true;
 #else
diff --git a/src/debug/di/rspriv.h b/src/debug/di/rspriv.h
index 8f369b7414..1db784b636 100644
--- a/src/debug/di/rspriv.h
+++ b/src/debug/di/rspriv.h
@@ -2317,9 +2317,7 @@ public:
 
     CorDebugInterfaceVersion    GetDebuggerVersion() const;
 
-#ifdef FEATURE_CORESYSTEM
 	HMODULE GetTargetCLR() { return m_targetCLR; }
-#endif
 
 private:
     bool IsCreateProcessSupported();
@@ -2339,9 +2337,7 @@ private:
 
 //Note - this code could be useful outside coresystem, but keeping the change localized
 // because we are late in the win8 release
-#ifdef FEATURE_CORESYSTEM
 	HMODULE m_targetCLR;
-#endif
 };
 
 
diff --git a/src/debug/di/shimprocess.cpp b/src/debug/di/shimprocess.cpp
index a6fc15407e..6572f2ac29 100644
--- a/src/debug/di/shimprocess.cpp
+++ b/src/debug/di/shimprocess.cpp
@@ -18,9 +18,6 @@
 #include <limits.h>
 #include "shimpriv.h"
 
-#if !defined(FEATURE_CORESYSTEM)
-#include <tlhelp32.h>
-#endif
 
 //---------------------------------------------------------------------------------------
 //
@@ -1082,114 +1079,8 @@ HRESULT ShimProcess::QueueFakeThreadAttachEventsNoOrder()
 //    sends the threads in an arbitrary order.
 HRESULT ShimProcess::QueueFakeThreadAttachEventsNativeOrder() 
 { 
-#ifdef FEATURE_CORESYSTEM
     _ASSERTE("NYI");
     return E_FAIL;
-#else
-    ICorDebugProcess * pProcess = GetProcess();
-
-    DWORD dwProcessId;
-    HRESULT hr = pProcess->GetID(&dwProcessId);
-    SIMPLIFYING_ASSUMPTION_SUCCEEDED(hr);
-    if (FAILED(hr))
-    {
-        return hr;
-    }
-
-    HANDLE hThreadSnap = INVALID_HANDLE_VALUE; 
-    THREADENTRY32 te32; 
-
-    // Take a snapshot of all running threads  
-    hThreadSnap = CreateToolhelp32Snapshot(TH32CS_SNAPTHREAD, 0); 
-    if (hThreadSnap == INVALID_HANDLE_VALUE) 
-    {
-        hr = HRESULT_FROM_GetLastError();
-        SIMPLIFYING_ASSUMPTION_SUCCEEDED(hr);
-        return hr; 
-    }
-    // HandleHolder doesn't deal with INVALID_HANDLE_VALUE, so we only assign if we have a legal value.
-    HandleHolder hSnapshotHolder(hThreadSnap);
-
-    // Fill in the size of the structure before using it. 
-    te32.dwSize = sizeof(THREADENTRY32); 
-
-    // Retrieve information about the first thread, and exit if unsuccessful
-    if (!Thread32First(hThreadSnap, &te32)) 
-    {
-        hr = HRESULT_FROM_GetLastError();
-        return hr;
-    }
-
-    // Now walk the thread list of the system,
-    // and display information about each thread
-    // associated with the specified process
-    do 
-    { 
-        if (te32.th32OwnerProcessID == dwProcessId)
-        {            
-            RSExtSmartPtr<ICorDebugThread> pThread;
-            pProcess->GetThread(te32.th32ThreadID, &pThread);
-            if (pThread != NULL)
-            {
-                // If we fail to get the appdomain for some reason, then then
-                // we can't dispatch this thread callback. But we can still
-                // finish enumerating.
-                RSExtSmartPtr<ICorDebugAppDomain> pAppDomain;
-                HRESULT hrGetAppDomain = pThread->GetAppDomain(&pAppDomain);
-                SIMPLIFYING_ASSUMPTION_SUCCEEDED(hrGetAppDomain);
-                if (pAppDomain != NULL)
-                {
-                    GetShimCallback()->CreateThread(pAppDomain, pThread);
-                    AddDuplicateCreationEvent(pThread);
-
-                    //fix for issue DevDiv2\DevDiv 77523 - threads are switched out in SQL don't get thread create notifications
-                    // mark that this thread has queued a create event
-                    CordbThread* pThreadInternal = static_cast<CordbThread*>(pThread.GetValue());
-                    pThreadInternal->SetCreateEventQueued();
-                }
-            }
-        }
-    } while(Thread32Next(hThreadSnap, &te32)); 
-
-
-    //fix for issue DevDiv2\DevDiv 77523 - threads are switched out in SQL don't get thread create notifications
-    //
-
-
-    // Threads which were switched out won't be present in the native thread order enumeration above.
-    // In order to not miss them we will enumerate all the managed thread objects and for any that we haven't
-    // already queued a notification for, we will queue a notification now.
-    RSExtSmartPtr<ICorDebugThreadEnum> pThreadEnum;
-    RSExtSmartPtr<ICorDebugThread> pThread;
-    hr = pProcess->EnumerateThreads(&pThreadEnum);
-    if (FAILED(hr))
-    {
-        return hr;
-    }
-
-    ULONG cDummy;
-    
-    while(SUCCEEDED(pThreadEnum->Next(1, &pThread, &cDummy)) && (pThread != NULL))
-    {
-        RSExtSmartPtr<ICorDebugAppDomain> pAppDomain;
-        hr = pThread->GetAppDomain(&pAppDomain);
-        CordbThread* pThreadInternal = static_cast<CordbThread*>(pThread.GetValue());
-
-        // Getting the appdomain shouldn't fail. If it does, we can't dispatch
-        // this callback, but we can still dispatch the other thread creates.
-        SIMPLIFYING_ASSUMPTION_SUCCEEDED(hr);
-        if (pAppDomain != NULL && !pThreadInternal->CreateEventWasQueued())
-        {
-            GetShimCallback()->CreateThread(pAppDomain, pThread);
-            AddDuplicateCreationEvent(pThread);
-            pThreadInternal->SetCreateEventQueued();
-        }
-        pThread.Clear();        
-    }
-
-
-    return S_OK;
-#endif
 }
 
 //---------------------------------------------------------------------------------------
@@ -1477,15 +1368,9 @@ void ShimProcess::QueueFakeAttachEvents()
     //
     // Third, Queue all Threads
     //
-#if !defined(FEATURE_DBGIPC_TRANSPORT_DI) && !defined(FEATURE_CORESYSTEM)   
-    // Use OS thread enumeration facilities to ensure that the managed thread
-    // thread order is the same as the corresponding native thread order.
-    QueueFakeThreadAttachEventsNativeOrder();
-#else
     // Use ICorDebug to enumerate threads. The order of managed threads may
     // not match the order the threads were created in.
     QueueFakeThreadAttachEventsNoOrder();
-#endif
 
     // Forth, Queue all Connections.
     // Enumerate connections is not exposed through ICorDebug, so we need to go use a private hook on CordbProcess.
@@ -1742,42 +1627,8 @@ CORDB_ADDRESS ShimProcess::GetCLRInstanceBaseAddress()
     CORDB_ADDRESS baseAddress = CORDB_ADDRESS(NULL);
     DWORD dwPid = m_pLiveDataTarget->GetPid();
 
-#if defined(FEATURE_CORESYSTEM)
     // Debugger attaching to CoreCLR via CoreCLRCreateCordbObject should have already specified CLR module address.
     // Code that help to find it now lives in dbgshim.
-#else
-    // get a "snapshot" of all modules in the target
-    HandleHolder hSnapshot = CreateToolhelp32Snapshot(TH32CS_SNAPMODULE, dwPid);
-    MODULEENTRY32 moduleEntry = { 0 };
-
-    if (hSnapshot == INVALID_HANDLE_VALUE)
-    {
-        // we haven't got a loaded CLR yet
-        baseAddress = CORDB_ADDRESS(NULL);
-    }
-    else
-    {
-        // we need to loop through the modules until we find mscorwks.dll
-        moduleEntry.dwSize = sizeof(MODULEENTRY32);
-
-        if (!Module32First(hSnapshot, &moduleEntry))
-        {
-            baseAddress = CORDB_ADDRESS(NULL);
-        }
-        else
-        {
-
-            do
-            {
-                if (!_wcsicmp(moduleEntry.szModule, MAKEDLLNAME_W(MAIN_CLR_MODULE_NAME_W)))
-                {
-                    // we found it, so save the base address
-                    baseAddress = PTR_TO_CORDB_ADDRESS(moduleEntry.modBaseAddr);
-                }
-            } while (Module32Next(hSnapshot, &moduleEntry));
-        }
-    }
-#endif
     return baseAddress;
 } // ShimProcess::GetCLRInstanceBaseAddress
 
diff --git a/src/debug/di/windowspipeline.cpp b/src/debug/di/windowspipeline.cpp
index c3050e3290..073a412608 100644
--- a/src/debug/di/windowspipeline.cpp
+++ b/src/debug/di/windowspipeline.cpp
@@ -134,36 +134,8 @@ BOOL WindowsNativePipeline::DebugSetProcessKillOnExit(bool fKillOnExit)
 // Enforces the bit set in code:WindowsNativePipeline::DebugSetProcessKillOnExit
 void WindowsNativePipeline::UpdateDebugSetProcessKillOnExit()
 {
-#if !defined(FEATURE_CORESYSTEM)
-    // Late bind to DebugSetProcessKillOnExit - WinXP and above only
-    HModuleHolder hKernel32;
-    hKernel32 = WszLoadLibrary(W("kernel32"));
-    SIMPLIFYING_ASSUMPTION(hKernel32 != NULL);
-    if (hKernel32 == NULL)
-        return;
-
-    typedef BOOL (*DebugSetProcessKillOnExitSig) (BOOL);
-    DebugSetProcessKillOnExitSig pDebugSetProcessKillOnExit = 
-        reinterpret_cast<DebugSetProcessKillOnExitSig>(GetProcAddress(hKernel32, "DebugSetProcessKillOnExit"));
-
-    // If the API doesn't exist (eg. Win2k) - there isn't anything we can do, just
-    // silently ignore the request.
-    if (pDebugSetProcessKillOnExit == NULL)
-        return;
-
-    BOOL ret = pDebugSetProcessKillOnExit(m_fKillOnExit);
-
-    // Not a good failure path here. 
-    // 1) This shouldn't fail.
-    // 2) Even if it does, this is likely called after the debuggee
-    // has already been created, and if this API fails, most scenarios will
-    // be unaffected, so we don't want to fail the overall debugging session. 
-    SIMPLIFYING_ASSUMPTION(ret);
-
-#else
 	// The API doesn't exit on CoreSystem, just return
 	return;
-#endif
 }
 
 // Create an process under the debugger.
@@ -249,69 +221,20 @@ HRESULT WindowsNativePipeline::DebugActiveProcess(MachineInfo machineInfo, DWORD
 // Determine (if possible) whether a debugger is attached to the target process
 HRESULT WindowsNativePipeline::IsRemoteDebuggerPresent(DWORD processId, BOOL* pfDebuggerPresent)
 {
-#if !defined(FEATURE_CORESYSTEM)
-
-    // Get a process handle for the process ID.
-    HandleHolder hProc = OpenProcess(PROCESS_QUERY_INFORMATION, FALSE, processId);
-    if (hProc == NULL)
-        return HRESULT_FROM_GetLastError();
-
-    // Delay-bind to CheckRemoteDebuggerPresent - WinXP SP1 and above only
-    HModuleHolder hKernel32;
-    hKernel32 = WszLoadLibrary(W("kernel32"));
-    if (hKernel32 == NULL)
-        return HRESULT_FROM_GetLastError();
-
-    typedef BOOL (*CheckRemoteDebuggerPresentSig) (HANDLE, PBOOL);
-    CheckRemoteDebuggerPresentSig pCheckRemoteDebuggerPresent = 
-        reinterpret_cast<CheckRemoteDebuggerPresentSig>(GetProcAddress(hKernel32, "CheckRemoteDebuggerPresent"));
-    if (pCheckRemoteDebuggerPresent == NULL)
-        return HRESULT_FROM_GetLastError();
-
-    // API exists - call it
-    if (!pCheckRemoteDebuggerPresent(hProc, pfDebuggerPresent))
-        return HRESULT_FROM_GetLastError();
-
-    return S_OK;
-#else
 
 	//CoreSystem doesn't have this API
 	return E_FAIL;
-#endif
 }
 
 // Detach
 HRESULT WindowsNativePipeline::DebugActiveProcessStop(DWORD processId)
 {
-#if !defined(FEATURE_CORESYSTEM)
-    // Late-bind to DebugActiveProcessStop since it's WinXP and above only
-    HModuleHolder hKernel32;
-    hKernel32 = WszLoadLibrary(W("kernel32"));
-    if (hKernel32 == NULL)
-        return HRESULT_FROM_GetLastError();
-
-    typedef BOOL (*DebugActiveProcessStopSig) (DWORD);
-    DebugActiveProcessStopSig pDebugActiveProcessStop = 
-        reinterpret_cast<DebugActiveProcessStopSig>(GetProcAddress(hKernel32, "DebugActiveProcessStop"));
-
-    // Win2K will fail here - can't find DebugActiveProcessStop
-    if (pDebugActiveProcessStop == NULL)
-        return HRESULT_FROM_GetLastError();
-
-    // Ok, the API exists, call it
-    if (!pDebugActiveProcessStop(processId))
-    {
-        // Detach itself failed
-        return HRESULT_FROM_GetLastError();
-    }
-#else
 	// The API exists, call it
     if (!::DebugActiveProcessStop(processId))
     {
         // Detach itself failed
         return HRESULT_FROM_GetLastError();
     }
-#endif
     return S_OK;
 }
 
@@ -364,56 +287,6 @@ BOOL WindowsNativePipeline::TerminateProcess(UINT32 exitCode)
 // Resume any suspended threads (but just once)
 HRESULT WindowsNativePipeline::EnsureThreadsRunning()
 {
-#ifdef FEATURE_CORESYSTEM
 	_ASSERTE("NYI");
 	return E_FAIL;
-#else
-    _ASSERTE(m_dwProcessId != 0);
-
-    // Take a snapshot of all running threads (similar to ShimProcess::QueueFakeThreadAttachEventsNativeOrder)
-    // Alternately we could return thread creation/exit in WaitForDebugEvent.  But we expect this to be used 
-    // very rarely, so no need to complicate more common codepaths.
-    HANDLE hThreadSnap = INVALID_HANDLE_VALUE; 
-    THREADENTRY32 te32; 
-
-    hThreadSnap = CreateToolhelp32Snapshot(TH32CS_SNAPTHREAD, 0); 
-    if (hThreadSnap == INVALID_HANDLE_VALUE) 
-        return HRESULT_FROM_GetLastError();
-
-    // HandleHolder doesn't deal with INVALID_HANDLE_VALUE, so we only assign if we have a legal value.
-    HandleHolder hSnapshotHolder(hThreadSnap);
-
-    // Fill in the size of the structure before using it. 
-    te32.dwSize = sizeof(THREADENTRY32); 
-
-    // Retrieve information about the first thread, and exit if unsuccessful
-    if (!Thread32First(hThreadSnap, &te32)) 
-        return HRESULT_FROM_GetLastError();
-
-    // Now walk the thread list of the system and attempt to resume any that are part of this process
-    // Ignore errors - this is a best effort (but ASSERT in CHK builds since we don't expect errors
-    // in practice - we expect the process to be frozen at a debug event, so no races etc.)
-
-    HRESULT hr = S_FALSE;   // no thread was resumed
-    do 
-    { 
-        if (te32.th32OwnerProcessID == m_dwProcessId)
-        {
-            HandleHolder hThread = ::OpenThread(THREAD_SUSPEND_RESUME, FALSE, te32.th32ThreadID);
-            _ASSERTE(hThread != NULL);
-            if (hThread != NULL)
-            {
-                // Resume each thread exactly once (if they were suspended multiple times, 
-                // then EnsureThreadsRunning would need to be called multiple times until it
-                // returned S_FALSE.
-                DWORD prevCount = ::ResumeThread(hThread);
-                _ASSERTE(prevCount >= 0);
-                if (prevCount >= 1)
-                    hr = S_OK;      // some thread was resumed
-            }
-        }
-    } while(Thread32Next(hThreadSnap, &te32)); 
-
-    return hr;
-#endif
 }
diff --git a/src/debug/ee/rcthread.cpp b/src/debug/ee/rcthread.cpp
index d4e707dd06..2244766c32 100644
--- a/src/debug/ee/rcthread.cpp
+++ b/src/debug/ee/rcthread.cpp
@@ -734,18 +734,7 @@ HRESULT DebuggerRCThread::SetupRuntimeOffsets(DebuggerIPCControlBlock * pDebugge
     pDebuggerRuntimeOffsets->m_excepNotForRuntimeBPAddr = (void*) ExceptionNotForRuntimeFlare;
     pDebuggerRuntimeOffsets->m_notifyRSOfSyncCompleteBPAddr = (void*) NotifyRightSideOfSyncCompleteFlare;
 
-#if !defined(FEATURE_CORESYSTEM)
-    // Grab the address of RaiseException in kernel32 because we have to play some games with exceptions
-    // that are generated there (just another reason why mixed mode debugging is shady). See bug 476768.
-    HMODULE hModule = WszGetModuleHandle(W("kernel32.dll"));
-    _ASSERTE(hModule != NULL);
-    PREFAST_ASSUME(hModule != NULL);
-    pDebuggerRuntimeOffsets->m_raiseExceptionAddr = GetProcAddress(hModule, "RaiseException");
-    _ASSERTE(pDebuggerRuntimeOffsets->m_raiseExceptionAddr != NULL);
-    hModule = NULL;
-#else
     pDebuggerRuntimeOffsets->m_raiseExceptionAddr = NULL;
-#endif
 #endif // FEATURE_INTEROP_DEBUGGING
 
     pDebuggerRuntimeOffsets->m_pPatches = DebuggerController::GetPatchTable();
@@ -801,7 +790,7 @@ static LONG _debugFilter(LPEXCEPTION_POINTERS ep, PVOID pv)
 
     SUPPRESS_ALLOCATION_ASSERTS_IN_THIS_SCOPE;
 
-#if defined(_DEBUG) || !defined(FEATURE_CORESYSTEM)
+#if defined(_DEBUG)
     DebuggerIPCEvent *event = ((DebugFilterParam *)pv)->event;
 
     DWORD pid = GetCurrentProcessId();
@@ -840,16 +829,6 @@ static LONG _debugFilter(LPEXCEPTION_POINTERS ep, PVOID pv)
 #endif
 
 // this message box doesn't work well on coresystem... we actually get in a recursive exception handling loop
-#ifndef FEATURE_CORESYSTEM
-    // We took an AV on the helper thread. This is a catastrophic situation so we can
-    // simply call the EE's catastrophic message box to display the error.
-    EEMessageBoxCatastrophic(
-        IDS_DEBUG_UNHANDLEDEXCEPTION_IPC, IDS_DEBUG_SERVICE_CAPTION,
-        type,
-        ep->ExceptionRecord->ExceptionCode,
-        GetIP(ep->ContextRecord),
-        pid, pid, tid, tid);
-#endif
 
     // For debugging, we can change the behavior by manually setting eax.
     // EXCEPTION_EXECUTE_HANDLER=1, EXCEPTION_CONTINUE_SEARCH=0, EXCEPTION_CONTINUE_EXECUTION=-1
diff --git a/src/debug/inc/dbgipcevents.h b/src/debug/inc/dbgipcevents.h
index 1b4dec7c16..8ab797106b 100644
--- a/src/debug/inc/dbgipcevents.h
+++ b/src/debug/inc/dbgipcevents.h
@@ -364,29 +364,6 @@ struct MSLAYOUT DebuggerIPCControlBlockTransport
 #include "dbgtransportsession.h"
 #endif // defined(FEATURE_DBGIPC_TRANSPORT_VM) || defined(FEATURE_DBGIPC_TRANSPORT_DI)
 
-#if defined(DBG_TARGET_X86) && !defined(FEATURE_CORESYSTEM)
-// We have an versioning requirement.
-// Certain portions of the v1.0 and v1.1 IPC block are shared. This is b/c a v1.1 debugger needs to be able
-// to look at a v2.0 app enough to recognize the version mismatch.
-// This check is only necessary for platforms that ran on v1.1 (Win32-x86)
-
-// Just to catch any potential illegal change in the IPC block, we assert the offsets against the offsets from v1.1.
-// The constants here are pulled from v1.1.
-// The RS will look at these versioning fields, so they absolutely must line up.
-static_assert_no_msg(offsetof(DebuggerIPCControlBlock, m_leftSideProtocolCurrent) == 0x10);
-static_assert_no_msg(offsetof(DebuggerIPCControlBlock, m_leftSideProtocolMinSupported) == 0x14);
-static_assert_no_msg(offsetof(DebuggerIPCControlBlock, m_rightSideProtocolCurrent) == 0x18);
-static_assert_no_msg(offsetof(DebuggerIPCControlBlock, m_rightSideProtocolMinSupported) == 0x1c);
-
-// Unfortunately, on detecting such failure, v1.1 will also null out LSEA, LSER and RSPH.
-// If these get adjusted, a version-mismatch attach  will effectively null out random fields.
-static_assert_no_msg(offsetof(DebuggerIPCControlBlock, m_paddingObsoleteLSEA) == 0x30);
-static_assert_no_msg(offsetof(DebuggerIPCControlBlock, m_paddingObsoleteLSER) == 0x34);
-static_assert_no_msg(offsetof(DebuggerIPCControlBlock, m_rightSideProcessHandle) == 0x38);
-
-
-
-#endif
 
 #define INITIAL_APP_DOMAIN_INFO_LIST_SIZE   16
 
diff --git a/src/debug/shared/dbgtransportsession.cpp b/src/debug/shared/dbgtransportsession.cpp
index 95fdf25457..6369feb521 100644
--- a/src/debug/shared/dbgtransportsession.cpp
+++ b/src/debug/shared/dbgtransportsession.cpp
@@ -2688,11 +2688,7 @@ bool DbgTransportSession::DbgTransportShouldInjectFault(DbgTransportFaultOp eOp,
         if (dwChance < (s_dwFaultInjection & DBG_TRANSPORT_FAULT_RATE_MASK))
         {
             DbgTransportLog(LC_FaultInject, "Injected fault for %s operation", szOpName);
-#if defined(FEATURE_CORESYSTEM)
         // not supported
-#else
-            WSASetLastError(WSAEFAULT);
-#endif // defined(FEATURE_CORESYSTEM)
             return true;
         }
     }
diff --git a/src/dlls/dbgshim/dbgshim.cpp b/src/dlls/dbgshim/dbgshim.cpp
index 5f15cabe97..90131012ce 100644
--- a/src/dlls/dbgshim/dbgshim.cpp
+++ b/src/dlls/dbgshim/dbgshim.cpp
@@ -1787,9 +1787,7 @@ GetContinueStartupEvent(
 
 #endif // !FEATURE_PAL
 
-#if defined(FEATURE_CORESYSTEM)
 #include "debugshim.h"
-#endif
 
 //-----------------------------------------------------------------------------
 // Public API.
@@ -1808,7 +1806,6 @@ CLRCreateInstance(
     REFIID riid, 
     LPVOID *ppInterface)
 {
-#if defined(FEATURE_CORESYSTEM)
 
     if (ppInterface == NULL)
         return E_POINTER;
@@ -1816,17 +1813,8 @@ CLRCreateInstance(
     if (clsid != CLSID_CLRDebugging || riid != IID_ICLRDebugging)
         return E_NOINTERFACE;
     
-#if defined(FEATURE_CORESYSTEM)
     GUID skuId = CLR_ID_ONECORE_CLR;
-#elif defined(FEATURE_CORECLR)
-    GUID skuId = CLR_ID_CORECLR;
-#else
-    GUID skuId = CLR_ID_V4_DESKTOP;
-#endif
     
     CLRDebuggingImpl *pDebuggingImpl = new CLRDebuggingImpl(skuId);
     return pDebuggingImpl->QueryInterface(riid, ppInterface);
-#else
-    return E_NOTIMPL;
-#endif
 }
\ No newline at end of file
diff --git a/src/inc/bbsweep.h b/src/inc/bbsweep.h
index d5526d8e5c..578711084f 100644
--- a/src/inc/bbsweep.h
+++ b/src/inc/bbsweep.h
@@ -186,95 +186,6 @@ private:
         {
             SECURITY_ATTRIBUTES * pSecurityAttributes = NULL;
 
-#ifndef FEATURE_CORESYSTEM // @CORESYSTEMTODO
-            PSECURITY_DESCRIPTOR pSD = NULL;
-            PSID pAdminSid = NULL;
-            HANDLE hToken = NULL;
-            PACL pACL = NULL;
-            LPVOID buffer = NULL;
-
-            if (!OpenProcessToken(GetCurrentProcess(), TOKEN_QUERY, &hToken))
-                goto cleanup;
-
-            // don't set pSecurityAttributes for Metro processes
-            if(!IsAppContainerProcess(hToken))
-            {
-                SECURITY_ATTRIBUTES securityAttributes;
-                PSID pUserSid = NULL;
-                SID_IDENTIFIER_AUTHORITY SIDAuthNT = SECURITY_NT_AUTHORITY;
-                DWORD retLength;
-
-#ifdef _PREFAST_
-#pragma warning(push)
-#pragma warning(disable:6211) // PREfast warning: Leaking memory 'pSD' due to an exception. 
-#endif /*_PREFAST_ */
-                pSD = (PSECURITY_DESCRIPTOR) new char[SECURITY_DESCRIPTOR_MIN_LENGTH];
-                if (!pSD)
-                    goto cleanup;
-
-                if (GetTokenInformation(hToken, TokenOwner, NULL, 0, &retLength))
-                    goto cleanup;
-
-                buffer = (LPVOID) new char[retLength];
-                if (!buffer)
-                    goto cleanup;
-#ifdef _PREFAST_
-#pragma warning(pop)
-#endif /*_PREFAST_*/
-
-                // Get the SID for the current user
-                if (!GetTokenInformation(hToken, TokenOwner, (LPVOID) buffer, retLength, &retLength))
-                    goto cleanup;
-
-                pUserSid = ((TOKEN_OWNER *) buffer)->Owner;
-
-                // Get the SID for the admin group
-                // Create a SID for the BUILTIN\Administrators group.
-                if(! AllocateAndInitializeSid(&SIDAuthNT, 2,
-                    SECURITY_BUILTIN_DOMAIN_RID,
-                    DOMAIN_ALIAS_RID_ADMINS,
-                    0, 0, 0, 0, 0, 0,
-                    &pAdminSid))
-                    goto cleanup;
-
-                EXPLICIT_ACCESS ea[2];
-                ZeroMemory(ea, 2 * sizeof(EXPLICIT_ACCESS));
-
-                // Initialize an EXPLICIT_ACCESS structure for an ACE.
-                // The ACE will allow the current user full access
-                ea[0].grfAccessPermissions = STANDARD_RIGHTS_ALL | SPECIFIC_RIGHTS_ALL; // KEY_ALL_ACCESS;
-                ea[0].grfAccessMode = SET_ACCESS;
-                ea[0].grfInheritance= NO_INHERITANCE;
-                ea[0].Trustee.TrusteeForm = TRUSTEE_IS_SID;
-                ea[0].Trustee.TrusteeType = TRUSTEE_IS_USER;
-                ea[0].Trustee.ptstrName  = (LPTSTR) pUserSid;
-
-                // Initialize an EXPLICIT_ACCESS structure for an ACE.
-                // The ACE will allow admins full access
-                ea[1].grfAccessPermissions = STANDARD_RIGHTS_ALL | SPECIFIC_RIGHTS_ALL; //KEY_ALL_ACCESS;
-                ea[1].grfAccessMode = SET_ACCESS;
-                ea[1].grfInheritance= NO_INHERITANCE;
-                ea[1].Trustee.TrusteeForm = TRUSTEE_IS_SID;
-                ea[1].Trustee.TrusteeType = TRUSTEE_IS_GROUP;
-                ea[1].Trustee.ptstrName  = (LPTSTR) pAdminSid;
-
-                if (SetEntriesInAcl(2, ea, NULL, &pACL) != ERROR_SUCCESS) 
-                    goto cleanup;
-
-                if (!InitializeSecurityDescriptor(pSD, SECURITY_DESCRIPTOR_REVISION))
-                    goto cleanup;
-
-                if (!SetSecurityDescriptorDacl(pSD, TRUE, pACL, FALSE))
-                    goto cleanup;
-
-                memset((void *) &securityAttributes, 0, sizeof(SECURITY_ATTRIBUTES));
-                securityAttributes.nLength              = sizeof(SECURITY_ATTRIBUTES);
-                securityAttributes.lpSecurityDescriptor = pSD;
-                securityAttributes.bInheritHandle       = FALSE;
-
-                pSecurityAttributes = &securityAttributes;
-            }
-#endif // !FEATURE_CORESYSTEM
 
             WCHAR objectName[MAX_LONGPATH] = {0};
             WCHAR objectNamePrefix[MAX_LONGPATH] = {0};
@@ -295,14 +206,6 @@ private:
             swprintf_s(objectName, MAX_LONGPATH, W("%sBBSweep_hProfWriterSemaphore"), objectNamePrefix);
             hProfWriterSemaphore = ::WszCreateSemaphore(pSecurityAttributes, MAX_COUNT, MAX_COUNT, objectName);
 
-#ifndef FEATURE_CORESYSTEM // @CORESYSTEMTODO
-cleanup:
-            if (pSD) delete [] ((char *) pSD);
-            if (pAdminSid) FreeSid(pAdminSid);
-            if (hToken) CloseHandle(hToken);
-            if (pACL) LocalFree(pACL);
-            if (buffer) delete [] ((char *) buffer);
-#endif
         }
 
         bInitialized = hSweepMutex          && 
@@ -382,7 +285,7 @@ cleanup:
                 }
                 else
                 {
-#if defined (FEATURE_CORESYSTEM) && !defined(CROSSGEN_COMPILE) && !defined(DACCESS_COMPILE)
+#if !defined(CROSSGEN_COMPILE) && !defined(DACCESS_COMPILE)
 #define MODULE_NAME W("api-ms-win-security-appcontainer-l1-1-0.dll")
 #else
 #define MODULE_NAME W("kernel32.dll")
diff --git a/src/inc/clrtypes.h b/src/inc/clrtypes.h
index 5f9de0cbf1..3b38bb3ed2 100644
--- a/src/inc/clrtypes.h
+++ b/src/inc/clrtypes.h
@@ -12,7 +12,7 @@
 #ifndef CLRTYPES_H_
 #define CLRTYPES_H_
 
-#if defined(_MSC_VER) && !defined(SOURCE_FORMATTING) && (!defined(FEATURE_CORECLR) || defined(FEATURE_CORESYSTEM))
+#if defined(_MSC_VER) && !defined(SOURCE_FORMATTING)
     // Prefer intsafe.h when available, which defines many of the MAX/MIN
     // values below (which is why they are in #ifndef blocks).
     #include <intsafe.h>
diff --git a/src/inc/legacyactivationshim.h b/src/inc/legacyactivationshim.h
index 4d8eaa5dd9..564ac9537e 100644
--- a/src/inc/legacyactivationshim.h
+++ b/src/inc/legacyactivationshim.h
@@ -819,46 +819,6 @@ namespace LegacyActivationShim
 #endif //LoadStringRC
 
 // Define this method only if it is not yet defined as macro (see ndp\clr\src\inc\UtilCode.h).
-#if !defined(LoadStringRCEx) && !defined(FEATURE_CORESYSTEM)
-    // --------------------------------------------------------------------------------------------
-    inline
-    HRESULT LoadStringRCEx(
-        LCID lcid,
-        UINT   nResourceID, 
-        __out_ecount(nMax) LPWSTR szBuffer,
-        int    nMax, 
-        int    fQuiet, 
-        int *pcwchUsed)
-    {
-        HRESULT hr = S_OK;
-
-        if (Util::HasNewActivationAPIs())
-        {
-            GET_CLRINFO(pInfo);
-            DWORD cchUsed = static_cast<DWORD>(nMax);
-            IfHrFailRet(pInfo->LoadErrorString(nResourceID, szBuffer, &cchUsed, lcid));
-            *pcwchUsed = cchUsed;
-        }
-        else
-        {
-            CALL_LEGACY_API(LoadStringRCEx,
-                            (LCID lcid,
-                             UINT   nResourceID, 
-                             LPWSTR szBuffer,
-                             int    nMax, 
-                             int    fQuiet, 
-                             int *pcwchUsed),
-                            (lcid,
-                             nResourceID,
-                             szBuffer,
-                             nMax,
-                             fQuiet,
-                             pcwchUsed));
-        }
-
-        return hr;
-    }
-#endif //LoadStringRCEx
 
     // --------------------------------------------------------------------------------------------
     inline
diff --git a/src/inc/newapis.h b/src/inc/newapis.h
index dfe77a5000..cdde78404c 100644
--- a/src/inc/newapis.h
+++ b/src/inc/newapis.h
@@ -150,7 +150,6 @@ typedef BOOL (CALLBACK* LOCALE_ENUMPROCEX)(LPWSTR, DWORD, LPARAM);
 
 namespace NewApis
 {
-#if defined(FEATURE_CORESYSTEM)
     __inline bool IsWindows7Platform()
     {
         return true;
@@ -166,94 +165,6 @@ namespace NewApis
         return false;
     }
 
-#else
-    // Return true if we're on Windows 7 or up (ie: if we have neutral native support and sorting knows about versions)
-    __inline bool IsWindows7Platform()
-    {
-        static int isRunningOnWindows7 = -1; // -1 notinitialized, 0 not running on Windows 7, other value means running on Windows 7
-
-        if (isRunningOnWindows7 == -1)
-        {
-            OSVERSIONINFOEX sVer;
-            ZeroMemory(&sVer, sizeof(OSVERSIONINFOEX));
-            sVer.dwOSVersionInfoSize = sizeof(OSVERSIONINFOEX);
-            sVer.dwMajorVersion = 6;
-            sVer.dwMinorVersion = 1;
-            sVer.dwPlatformId = VER_PLATFORM_WIN32_NT;
-
-            DWORDLONG dwlConditionMask = 0;
-            VER_SET_CONDITION(dwlConditionMask, CLR_VER_MAJORVERSION, VER_GREATER_EQUAL);
-            VER_SET_CONDITION(dwlConditionMask, CLR_VER_MINORVERSION, VER_GREATER_EQUAL);
-            VER_SET_CONDITION(dwlConditionMask, CLR_VER_PLATFORMID, VER_EQUAL);
-
-            if(VerifyVersionInfo(&sVer, CLR_VER_MAJORVERSION|CLR_VER_MINORVERSION|CLR_VER_PLATFORMID, dwlConditionMask))
-            {
-                isRunningOnWindows7 = 1;
-            }
-            else
-            {
-                isRunningOnWindows7 = 0;
-            }
-        }
-
-        return isRunningOnWindows7 == 1;
-    }
-
-    //
-    // IsVistaPlatform return true if running on Vista and false if running on pre or post Vista
-    //
-    __inline BOOL IsVistaPlatform()
-    {
-        static int isRunningOnVista = -1; // -1 notinitialized, 0 not running on Vista, other value meanse running on Vista
-
-        if (isRunningOnVista == -1)
-        {
-            OSVERSIONINFOEX sVer;
-            ZeroMemory(&sVer, sizeof(OSVERSIONINFOEX));
-            sVer.dwOSVersionInfoSize = sizeof(OSVERSIONINFOEX);
-            sVer.dwMajorVersion = 6;
-            sVer.dwMinorVersion = 0;
-            sVer.dwPlatformId = VER_PLATFORM_WIN32_NT;
-
-            DWORDLONG dwlConditionMask = 0;
-            VER_SET_CONDITION(dwlConditionMask, CLR_VER_MAJORVERSION, VER_EQUAL);
-            VER_SET_CONDITION(dwlConditionMask, CLR_VER_MINORVERSION, VER_EQUAL);
-            VER_SET_CONDITION(dwlConditionMask, CLR_VER_PLATFORMID, VER_EQUAL);
-
-            if(VerifyVersionInfo(&sVer, CLR_VER_MAJORVERSION|CLR_VER_MINORVERSION|CLR_VER_PLATFORMID, dwlConditionMask))
-            {
-                isRunningOnVista = 1;
-            }
-            else
-            {
-                isRunningOnVista = 0;
-            }
-        }
-
-        return isRunningOnVista == 1;
-    }
-
-
-    __inline BOOL IsZhTwSku()
-    {
-        const INT32 LANGID_ZH_TW = 0x0404;
-        LPCWSTR DEFAULT_REGION_NAME_0404 = W("\x53f0\x7063");
-
-        if(::GetSystemDefaultUILanguage() == LANGID_ZH_TW)
-        {
-            WCHAR wszBuffer[32];
-            int result = ::GetLocaleInfoW(LANGID_ZH_TW, LOCALE_SNATIVECTRYNAME, wszBuffer, 32);
-            if (result)
-            {
-                if (wcsncmp(wszBuffer, DEFAULT_REGION_NAME_0404, 3) != 0)
-                {
-                    return true;
-                } 
-            }
-        }
-        return false;
-    }
-#endif // FEATURE_CORESYSTEM
 
     __inline BOOL NotLeakingFrameworkOnlyCultures(__in LPCWSTR lpLocaleName)
     {
diff --git a/src/inc/ostype.h b/src/inc/ostype.h
index c18d05a5f6..91a0e7766a 100644
--- a/src/inc/ostype.h
+++ b/src/inc/ostype.h
@@ -38,19 +38,6 @@ extern BOOL                gExInfoIsServer;
 
 void InitRunningOnVersionStatus();
 
-#if defined(FEATURE_COMINTEROP) && !defined(FEATURE_CORESYSTEM)
-typedef enum
-{
-    WINRT_STATUS_UNINITED = 0,
-    WINRT_STATUS_UNSUPPORTED,
-    WINRT_STATUS_SUPPORTED
-}
-WinRTStatusEnum;
-
-extern WinRTStatusEnum      gWinRTStatus;
-
-void InitWinRTStatus();
-#endif // FEATURE_COMINTEROP && !FEATURE_CORESYSTEM
 
 //*****************************************************************************
 //
@@ -71,16 +58,7 @@ void InitWinRTStatus();
 inline BOOL RunningOnWin7()
 {
     WRAPPER_NO_CONTRACT;
-#if defined(_ARM_) || defined(FEATURE_CORESYSTEM)
     return TRUE;
-#else
-    if (gRunningOnStatus == RUNNING_ON_STATUS_UNINITED)
-    {
-        InitRunningOnVersionStatus();
-    }
-
-    return (gRunningOnStatus >= RUNNING_ON_WIN7) ? TRUE : FALSE;
-#endif
 }
 
 //*****************************************************************************
@@ -137,32 +115,11 @@ inline BOOL ExOSInfoRunningOnServer()
 
 #ifdef FEATURE_COMINTEROP
 
-#ifdef FEATURE_CORESYSTEM
 
 inline BOOL WinRTSupported()
 {
     return RunningOnWin8();
 }
-#else
-inline BOOL WinRTSupported()
-{
-    STATIC_CONTRACT_NOTHROW;
-    STATIC_CONTRACT_GC_NOTRIGGER;
-    STATIC_CONTRACT_CANNOT_TAKE_LOCK;
-    STATIC_CONTRACT_SO_TOLERANT;
-    
-#ifdef CROSSGEN_COMPILE
-    return TRUE;
-#endif
-
-    if (gWinRTStatus == WINRT_STATUS_UNINITED)
-    {
-        InitWinRTStatus();
-    }
-
-    return gWinRTStatus == WINRT_STATUS_SUPPORTED;
-}
-#endif // FEATURE_CORESYSTEM
 
 #endif // FEATURE_COMINTEROP
 
diff --git a/src/inc/switches.h b/src/inc/switches.h
index 762077a8f4..9faf620dc7 100644
--- a/src/inc/switches.h
+++ b/src/inc/switches.h
@@ -240,11 +240,9 @@
 #define FEATURE_DOUBLE_ALIGNMENT_HINT
 #endif
 
-#if defined(FEATURE_CORESYSTEM)
 #define FEATURE_MINIMETADATA_IN_TRIAGEDUMPS
-#endif // defined(FEATURE_CORESYSTEM)
 
-#if defined(FEATURE_PREJIT) && defined(FEATURE_CORECLR) && defined(FEATURE_CORESYSTEM)
+#if defined(FEATURE_PREJIT) && defined(FEATURE_CORECLR)
 // Desktop CLR allows profilers and debuggers to opt out of loading NGENd images, and to
 // JIT everything instead. "FEATURE_TREAT_NI_AS_MSIL_DURING_DIAGNOSTICS" is roughly the
 // equivalent for Apollo, where MSIL images may not be available at all.
diff --git a/src/inc/winwrap.h b/src/inc/winwrap.h
index 4a012d3726..f44aae5750 100644
--- a/src/inc/winwrap.h
+++ b/src/inc/winwrap.h
@@ -466,7 +466,7 @@
 #define WszObjectDeleteAuditAlarm ObjectDeleteAuditAlarmW
 #define WszPrivilegedServiceAuditAlarm PrivilegedServiceAuditAlarmW
 #define WszIsBadStringPtr __DO_NOT_USE__WszIsBadStringPtr__
-#if !defined(FEATURE_CORESYSTEM) || defined(CROSSGEN_COMPILE)
+#if defined(CROSSGEN_COMPILE)
 #define WszLookupAccountSid LookupAccountSidW
 #endif
 #define WszLookupAccountName LookupAccountNameW
@@ -659,7 +659,6 @@
 // winnetwk.h
 #define WszWNetGetConnection WNetGetConnectionW
 
-#ifdef FEATURE_CORESYSTEM
 
 // CoreSystem has CreateSemaphoreExW but not CreateSemaphoreW.
 #undef WszCreateSemaphore
@@ -671,7 +670,6 @@
 #undef GetFileVersionInfoSize
 #define GetFileVersionInfoSize(_filename, _handle) GetFileVersionInfoSizeEx(0, (_filename), (_handle))
 
-#endif // FEATURE_CORESYSTEM
 
 #ifndef _T
 #define _T(str) W(str)
@@ -1021,7 +1019,7 @@ inline int LateboundMessageBoxA(HWND hWnd,
     return LateboundMessageBoxW(hWnd, wszText, wszCaption, uType);
 }
 
-#if defined(FEATURE_CORESYSTEM) && !defined(CROSSGEN_COMPILE)
+#if !defined(CROSSGEN_COMPILE)
 
 #define MessageBoxW LateboundMessageBoxW
 #define MessageBoxA LateboundMessageBoxA
diff --git a/src/pal/prebuilt/inc/asm_version.h b/src/pal/prebuilt/inc/asm_version.h
index 977c8dd188..f1f2b0ad7d 100644
--- a/src/pal/prebuilt/inc/asm_version.h
+++ b/src/pal/prebuilt/inc/asm_version.h
@@ -2,18 +2,11 @@
 // The .NET Foundation licenses this file to you under the MIT license.
 // See the LICENSE file in the project root for more information.
 #if defined(SILVERLIGHT) || defined(FEATURE_CORECLR)
-#if defined(FEATURE_CORESYSTEM)
 #define asm_rmj              4
 #define asm_rmm              0
 #define asm_rup              0
 #define asm_rpt              0
 #else
-#define asm_rmj              5
-#define asm_rmm              0
-#define asm_rup              5
-#define asm_rpt              0
-#endif
-#else
 #define asm_rmj              4
 #define asm_rmm              0
 #define asm_rup              0
diff --git a/src/strongname/api/strongname.cpp b/src/strongname/api/strongname.cpp
index 00b115698c..2562f4c796 100644
--- a/src/strongname/api/strongname.cpp
+++ b/src/strongname/api/strongname.cpp
@@ -906,14 +906,8 @@ SNAPI StrongNameGetPublicKeyEx (LPCWSTR   wszKeyContainer,    // [in] desired ke
                                0, 0, &hKey))
             goto Error;
     } else {
-#if !defined(FEATURE_CORESYSTEM)
-        // Else fetch the signature key pair from the container.
-        if (!CryptGetUserKey(hProv, g_uKeySpec, &hKey))
-            goto Error;
-#else // FEATURE_CORESYSTEM
         SetLastError(E_NOTIMPL);
         goto Error;
-#endif // !FEATURE_CORESYSTEM
     }
 
     // Determine the length of the public key part as a blob.
diff --git a/src/utilcode/securitywrapper.cpp b/src/utilcode/securitywrapper.cpp
index 0f146ab55e..c357ab6146 100644
--- a/src/utilcode/securitywrapper.cpp
+++ b/src/utilcode/securitywrapper.cpp
@@ -207,116 +207,6 @@ exit:
     return hr;
 }
 
-#ifndef FEATURE_CORESYSTEM
-//-----------------------------------------------------------------------------
-// get the sid of a given process id using WTSEnumerateProcesses
-// @todo: Make this function fail when WTSEnumerateProcesses is not available
-// Or is it always available on all of our platform?
-//
-// Caller remember to call delete on *ppSid
-//-----------------------------------------------------------------------------
-HRESULT GetSidFromProcessEXWorker(DWORD dwProcessId, PSID *ppSid)
-{
-    CONTRACTL
-    {
-        NOTHROW;
-        GC_NOTRIGGER;
-        PRECONDITION(CheckPointer(ppSid));
-    }
-    CONTRACTL_END;
-
-    HRESULT            hr = S_OK;
-    PWTS_PROCESS_INFOW rgProcessInfo = NULL;
-    DWORD              dwNumProcesses;
-    DWORD              iProc;
-    DWORD              cbSid;
-    PSID               pSid = NULL;
-
-    LOG((LF_CORDB, LL_INFO10000,
-         "SecurityUtil::GetSidFromProcessEx: 0x%08x\n",
-         dwProcessId));
-
-
-    *ppSid = NULL;
-    if (!WTSEnumerateProcessesW(WTS_CURRENT_SERVER_HANDLE,   // use local server
-                                0,              // Reserved must be zero
-                                1,              // version must be 1
-                                &rgProcessInfo, // Receives pointer to process list
-                                &dwNumProcesses))
-    {
-        hr = HRESULT_FROM_GetLastError();
-        goto exit;
-    }
-
-    for (iProc = 0; iProc < dwNumProcesses; iProc++)
-    {
-
-        if (rgProcessInfo[iProc].ProcessId == dwProcessId)
-        {
-            if (rgProcessInfo[iProc].pUserSid == NULL)
-            {
-                LOG((LF_CORDB, LL_INFO10000,
-                     "SecurityUtil::GetSidFromProcessEx is not able to retreive SID\n"));
-
-                // if there is no Sid for the user, don't call GetLengthSid.
-                // It will crash! It is ok to return E_FAIL as caller will ignore it.
-                hr = E_FAIL;
-                goto exit;
-            }
-            cbSid = GetLengthSid(rgProcessInfo[iProc].pUserSid);
-            pSid = new (nothrow) BYTE[cbSid];
-            if (pSid == NULL)
-            {
-                hr = E_OUTOFMEMORY;
-            }
-            else
-            {
-                if (!CopySid(cbSid, pSid, rgProcessInfo[iProc].pUserSid))
-                {
-                    hr = HRESULT_FROM_GetLastError();
-                }
-                else
-                {
-                    // We are done. Go to exit
-                    hr = S_OK;
-                }
-            }
-
-            // we already find a match. Even if we fail from memory allocation of CopySid, still
-            // goto exit.
-            goto exit;
-        }
-    }
-
-    // Walk the whole list and cannot find the matching PID
-    // Find a better error code.
-    hr = E_FAIL;
-
-exit:
-
-    if (rgProcessInfo)
-    {
-        WTSFreeMemory(rgProcessInfo);
-    }
-
-    if (FAILED(hr) && pSid)
-    {
-        delete [] (reinterpret_cast<BYTE*>(pSid));
-    }
-
-    if (SUCCEEDED(hr))
-    {
-        _ASSERTE(pSid);
-        *ppSid = pSid;
-    }
-    LOG((LF_CORDB, LL_INFO10000,
-         "SecurityUtil::GetSidFromProcessEx return hr : 0x%08x\n",
-         hr));
-
-
-    return hr;
-}
-#endif // !FEATURE_CORESYSTEM
 
 //-----------------------------------------------------------------------------
 // The functions below initialize this SidBuffer instance with a Sid from
@@ -362,12 +252,6 @@ HRESULT SidBuffer::InitFromProcessNoThrow(DWORD pid)
 
     _ASSERTE(m_pBuffer == NULL);
     HRESULT hr = GetSidFromProcessWorker(pid, kOwnerSid, (PSID *) &m_pBuffer);
-#ifndef FEATURE_CORESYSTEM
-    if (FAILED(hr))
-    {
-        hr = GetSidFromProcessEXWorker(pid, (PSID *) &m_pBuffer);
-    }
-#endif // !FEATURE_CORESYSTEM
     if (FAILED(hr))
     {
         return hr;
@@ -527,12 +411,6 @@ HRESULT SidBuffer::InitFromProcessUserNoThrow(DWORD pid)
 
     _ASSERTE(m_pBuffer == NULL);
     HRESULT hr = GetSidFromProcessWorker(pid, kUserSid, (PSID *) &m_pBuffer);
-#ifndef FEATURE_CORESYSTEM
-    if (FAILED(hr))
-    {
-        hr = GetSidFromProcessEXWorker(pid, (PSID *) &m_pBuffer);
-    }
-#endif // !FEATURE_CORESYSTEM
     if (FAILED(hr))
     {
         return hr;
diff --git a/src/utilcode/sstring.cpp b/src/utilcode/sstring.cpp
index 7c332e08c3..cf495ccb15 100644
--- a/src/utilcode/sstring.cpp
+++ b/src/utilcode/sstring.cpp
@@ -2237,11 +2237,7 @@ void SString::PVPrintf(const WCHAR *format, va_list args)
     {
         // First, try to use the existing buffer
         va_copy(ap, args);
-#if defined(FEATURE_CORESYSTEM)
         int result = _vsnwprintf_s(GetRawUnicode(), GetRawCount()+1, _TRUNCATE, format, ap);
-#else
-        int result = _vswprintf_p(GetRawUnicode(), GetRawCount()+1, format, ap);
-#endif
         va_end(ap);
         if (result >= 0)
         {
@@ -2271,11 +2267,7 @@ void SString::PVPrintf(const WCHAR *format, va_list args)
         errno = 0;
 
         va_copy(ap, args);
-#if defined(FEATURE_CORESYSTEM)
         int result = _vsnwprintf_s(GetRawUnicode(), GetRawCount()+1, _TRUNCATE, format, ap);
-#else
-        int result = _vswprintf_p(GetRawUnicode(), GetRawCount()+1, format, ap);
-#endif
         va_end(ap);
 
         if (result >= 0)
diff --git a/src/utilcode/util.cpp b/src/utilcode/util.cpp
index 33722e5297..45b5125206 100644
--- a/src/utilcode/util.cpp
+++ b/src/utilcode/util.cpp
@@ -31,60 +31,7 @@ UINT32 g_nClrInstanceId = 0;
 
 //********** Code. ************************************************************
 
-#if defined(FEATURE_COMINTEROP) && !defined(FEATURE_CORESYSTEM)
-extern WinRTStatusEnum gWinRTStatus = WINRT_STATUS_UNINITED;
-#endif // FEATURE_COMINTEROP && !FEATURE_CORESYSTEM
 
-#if defined(FEATURE_COMINTEROP) && !defined(FEATURE_CORESYSTEM)
-//------------------------------------------------------------------------------
-//
-// Attempt to detect the presense of Windows Runtime support on the current OS.
-// Our algorithm to do this is to ensure that:
-//      1. combase.dll exists
-//      2. combase.dll contains a RoInitialize export
-//
-
-void InitWinRTStatus()
-{
-    STATIC_CONTRACT_NOTHROW;
-    STATIC_CONTRACT_GC_NOTRIGGER;
-    STATIC_CONTRACT_CANNOT_TAKE_LOCK;
-    STATIC_CONTRACT_SO_TOLERANT;
-    
-    WinRTStatusEnum winRTStatus = WINRT_STATUS_UNSUPPORTED;
-
-    const WCHAR wszComBaseDll[] = W("\\combase.dll");
-    const SIZE_T cchComBaseDll = _countof(wszComBaseDll);
-
-    WCHAR wszComBasePath[MAX_LONGPATH + 1];
-    const SIZE_T cchComBasePath = _countof(wszComBasePath);
-
-    ZeroMemory(wszComBasePath, cchComBasePath * sizeof(wszComBasePath[0]));
-
-    UINT cchSystemDirectory = WszGetSystemDirectory(wszComBasePath, MAX_LONGPATH);
-
-    // Make sure that we're only probing in the system directory.  If we can't find the system directory, or
-    // we find it but combase.dll doesn't fit into it, we'll fall back to a safe default of saying that WinRT
-    // is simply not present.
-    if (cchSystemDirectory > 0 && cchComBasePath - cchSystemDirectory >= cchComBaseDll)
-    {
-        if (wcscat_s(wszComBasePath, wszComBaseDll) == 0)
-        {
-            HModuleHolder hComBase(WszLoadLibrary(wszComBasePath));
-            if (hComBase != NULL)
-            {
-                FARPROC activateInstace = GetProcAddress(hComBase, "RoInitialize");
-                if (activateInstace != NULL)
-                {
-                    winRTStatus = WINRT_STATUS_SUPPORTED;
-                }
-            }
-        }
-    }
-
-    gWinRTStatus = winRTStatus;
-}
-#endif // FEATURE_COMINTEROP && !FEATURE_CORESYSTEM
 //*****************************************************************************
 // Convert a string of hex digits into a hex value of the specified # of bytes.
 //*****************************************************************************
diff --git a/src/utilcode/utilmessagebox.cpp b/src/utilcode/utilmessagebox.cpp
index 4559d16b7f..3d13489b84 100644
--- a/src/utilcode/utilmessagebox.cpp
+++ b/src/utilcode/utilmessagebox.cpp
@@ -18,11 +18,6 @@
 #include "ndpversion.h"
 #include "../dlls/mscorrc/resource.h"
 #include "ex.h"
-#if !defined(FEATURE_CORESYSTEM)
-#undef NTDDI_VERSION
-#define NTDDI_VERSION NTDDI_WIN7
-#include "commctrl.h"
-#endif
 
 #if !defined(SELF_NO_HOST) && !defined(FEATURE_CORECLR)
 
@@ -72,16 +67,6 @@ BOOL ShouldDisplayMsgBoxOnCriticalFailure()
 }
 
 
-#if !defined(FEATURE_CORESYSTEM) && !defined(FEATURE_CORECLR)
-enum ProbedTaskDialogIndirectState
-{
-    ProbedTaskDialogIndirectState_NotProbed = 0,
-    ProbedTaskDialogIndirectState_NotAvailable = 1,
-    ProbedTaskDialogIndirectState_Available = 2
-};
-
-static ProbedTaskDialogIndirectState siProbedTaskDialogIndirect = ProbedTaskDialogIndirectState_NotProbed;
-#endif // !FEATURE_CORESYSTEM && !FEATURE_CORECLR
 
 
 // We'd like to use TaskDialogIndirect for asserts coming from managed code in particular
@@ -109,157 +94,7 @@ int MessageBoxImpl(
     }
     CONTRACTL_END;
 
-#if defined(FEATURE_CORESYSTEM) || defined (FEATURE_CORECLR)
     return WszMessageBox(hWnd, message, title, uType);
-#else
-    bool mustUseMessageBox = false;  // Mac, Silverlight, pre-Vista?  Do we support this type of message box?
-    decltype(TaskDialogIndirect)* pfnTaskDialogIndirect = NULL;
-    ULONG_PTR cookie = NULL;  // For activation context.
-    bool activatedActivationContext = false;
-    HModuleHolder hmodComctl32;
-    HANDLE hActCtx = INVALID_HANDLE_VALUE;
-
-    // Note: TaskDialogIndirect is only in the v6 and above versions of comctl32.  Windows
-    // stores that library in the WinSxS directory in a directory with 
-    // "Microsoft.Windows.Common-Controls" in the name.  Your application can only see
-    // this library if the linker has added a manifest dependency on the V6 common controls
-    // to your application.  Or, you can create an activation context to make this work,
-    // if your library also has the appropriate manifest dependency.
-    // Also, I'm not going to leave comctl32.dll mapped, to ensure it can't somehow 
-    // interfere with older versions.  Therefore, re-load comctl32.dll every time through
-    // this method.  We will record whether TaskDialogIndirect is available though, so
-    // we can fall back to MessageBox faster.
-
-    // We don't yet have a perfect mapping from all MessageBox behavior to TaskDialogIndirect behavior.
-    // Use MessageBox to avoid most of this complexity.
-    if (((uType & MB_ICONMASK) != MB_ICONWARNING) && (uType & MB_ICONMASK) != MB_ICONERROR  ||
-        (uType & MB_TYPEMASK) != MB_ABORTRETRYIGNORE ||
-        (uType & MB_DEFMASK) != 0 ||
-        (uType & MB_MODEMASK) != 0 ||
-        (uType & MB_MISCMASK) != 0)
-        mustUseMessageBox = true;
-    else if (mustUseMessageBox || siProbedTaskDialogIndirect == ProbedTaskDialogIndirectState_NotAvailable)
-        mustUseMessageBox = true;
-    else {
-        // Replace our application's ActivationContext temporarily, load comctl32
-        // & look for TaskDialogIndirect.  Don't cache pointer.
-        // The following code was suggested by some Windows experts.  We do not want
-		// to add a manifest to our library saying we use comctl32 v6, because that
-		// will mean loading a lot of extra libraries on startup (a significant perf hit).
-		// We could either store the manifest as a resource, or more creatively since
-		// we are effectively a Windows component, rely on %windir%\WindowsShell.manifest.
-        ACTCTX ctx = { sizeof(ACTCTX) };
-        ctx.dwFlags = 0;
-        StackSString manifestPath;  // Point this at %windir%\WindowsShell.manifest, for comctl32 version 6.
-        UINT numChars = WszGetWindowsDirectory(manifestPath.OpenUnicodeBuffer(MAX_PATH_FNAME), MAX_PATH_FNAME);
-        if (numChars == 0 || numChars >= MAX_PATH_FNAME)
-        {
-            _ASSERTE(0);  // How did this fail?
-        }
-        else {
-            manifestPath.CloseBuffer(numChars);
-            if (manifestPath[manifestPath.GetCount() - 1] != W('\\'))
-                manifestPath.Append(W('\\'));
-            manifestPath.Append(W("WindowsShell.manifest"));  // Other Windows components have already loaded this.
-            ctx.lpSource = manifestPath.GetUnicode();
-            hActCtx = CreateActCtx(&ctx);
-            if (hActCtx != INVALID_HANDLE_VALUE)
-            {           
-                if (!ActivateActCtx(hActCtx, &cookie))
-                {
-                    cookie = NULL;
-                    _ASSERTE(0);  // Why did ActivateActCtx fail?  (We'll continue executing & cope with the failure.)
-                }
-                else {
-                    activatedActivationContext = true;
-                    // Activation context was replaced - now we can load comctl32 version 6.
-                    hmodComctl32 = WszLoadLibrary(W("comctl32.dll"));
-
-                    if (hmodComctl32 != INVALID_HANDLE_VALUE) {
-                        pfnTaskDialogIndirect = (decltype(TaskDialogIndirect)*)GetProcAddress(hmodComctl32, "TaskDialogIndirect");
-                        if (pfnTaskDialogIndirect == NULL) {
-                            hmodComctl32.Release();
-                        }
-                    }
-                }
-            }
-        }
-
-        siProbedTaskDialogIndirect = (pfnTaskDialogIndirect == NULL) ? ProbedTaskDialogIndirectState_NotAvailable : ProbedTaskDialogIndirectState_Available;
-        mustUseMessageBox = (pfnTaskDialogIndirect == NULL);
-    }
-
-    int result = MB_OK;
-    if (mustUseMessageBox) {
-        result = WszMessageBox(hWnd, message, title, uType);
-    }
-    else {
-        _ASSERTE(pfnTaskDialogIndirect != NULL);
-        int nButtonPressed                  = 0;
-        TASKDIALOGCONFIG config             = {0};
-        config.cbSize                       = sizeof(config);
-        config.hwndParent                   = hWnd;
-        config.dwCommonButtons              = 0;
-        config.pszWindowTitle               = title;
-        config.dwFlags                      = (uType & MB_RTLREADING) ? TDF_RTL_LAYOUT : 0;
-
-        // Set the user-visible icon in the window.
-        _ASSERTE(((uType & MB_ICONMASK) == MB_ICONWARNING) || ((uType & MB_ICONMASK) == MB_ICONERROR));
-        config.pszMainIcon                  = ((uType & MB_ICONMASK) == MB_ICONWARNING) ? TD_WARNING_ICON : TD_ERROR_ICON;
-
-        config.pszMainInstruction           = title;
-        config.pszContent                   = message;
-        config.pszExpandedInformation       = detailedText;
-
-        // Set up the buttons
-        // Note about button hot keys: Windows keeps track of of where the last input came from
-        // (ie, mouse or keyboard).  If you use the mouse to interact w/ one dialog box and then use
-        // the keyboard, the next dialog will not include hot keys.  This is a Windows feature to
-        // minimize clutter on the screen for mouse users.
-        _ASSERTE((uType & MB_TYPEMASK) == MB_ABORTRETRYIGNORE);
-        StackSString abortLabel, debugLabel, ignoreLabel;
-        const WCHAR *pAbortLabel, *pDebugLabel, *pIgnoreLabel;
-
-        if (abortLabel.LoadResource(CCompRC::Optional, IDS_DIALOG_BOX_ABORT_BUTTON))
-            pAbortLabel = abortLabel.GetUnicode();
-        else
-            pAbortLabel = W("&Abort");
-        if (debugLabel.LoadResource(CCompRC::Optional, IDS_DIALOG_BOX_DEBUG_BUTTON))
-            pDebugLabel = debugLabel.GetUnicode();
-        else
-            pDebugLabel = W("&Debug");
-        if (ignoreLabel.LoadResource(CCompRC::Optional, IDS_DIALOG_BOX_IGNORE_BUTTON))
-            pIgnoreLabel = ignoreLabel.GetUnicode();
-        else
-            pIgnoreLabel = W("&Ignore");
-
-        const TASKDIALOG_BUTTON abortDebugIgnoreButtons[] = { 
-            { IDOK, pAbortLabel },
-            { IDRETRY, pDebugLabel },
-            { IDIGNORE, pIgnoreLabel }
-        };
-        config.pButtons = abortDebugIgnoreButtons;
-        config.cButtons = 3;
-
-        HRESULT hr = pfnTaskDialogIndirect(&config, &nButtonPressed, NULL, NULL);
-        _ASSERTE(hr == S_OK);
-        if (hr == S_OK) {
-            result = nButtonPressed;
-        }
-        else {
-            result = IDOK;
-        }
-
-        _ASSERTE(result == IDOK || result == IDRETRY || result == IDIGNORE);
-    }
-
-    if (activatedActivationContext) {
-        DeactivateActCtx(0, cookie);
-        ReleaseActCtx(hActCtx);  // perf isn't important so we won't bother caching the actctx
-    }
- 
-    return result;
-#endif
 }
 
 int UtilMessageBoxVA(
diff --git a/src/utilcode/winfix.cpp b/src/utilcode/winfix.cpp
index 3a044865ec..d6bd59cac8 100644
--- a/src/utilcode/winfix.cpp
+++ b/src/utilcode/winfix.cpp
@@ -231,21 +231,6 @@ BOOL RunningInteractive()
     if (fInteractive != -1)
         return fInteractive != 0;
 
-#if !defined(FEATURE_CORESYSTEM)
-        HWINSTA hwinsta = NULL;
-
-        if ((hwinsta = GetProcessWindowStation() ) != NULL)
-        {
-            DWORD lengthNeeded;
-            USEROBJECTFLAGS flags;
-
-            if (GetUserObjectInformationW (hwinsta, UOI_FLAGS, &flags, sizeof(flags), &lengthNeeded))
-           {
-                    if ((flags.dwFlags & WSF_VISIBLE) == 0)
-                        fInteractive = 0;
-            }
-        }
-#endif // !FEATURE_CORESYSTEM
 
     if (fInteractive != 0)
         fInteractive = 1;
diff --git a/src/vm/assembly.cpp b/src/vm/assembly.cpp
index 2db3e23fff..08792c92f4 100644
--- a/src/vm/assembly.cpp
+++ b/src/vm/assembly.cpp
@@ -4063,7 +4063,6 @@ BOOL Assembly::CanBeShared(DomainAssembly *pDomainAssembly)
 
 #endif // FEATURE_LOADER_OPTIMIZATION
 
-#if defined(FEATURE_APTCA) || defined(FEATURE_CORESYSTEM)
 BOOL Assembly::AllowUntrustedCaller()
 {
     CONTRACTL
@@ -4076,7 +4075,6 @@ BOOL Assembly::AllowUntrustedCaller()
 
     return ModuleSecurityDescriptor::GetModuleSecurityDescriptor(this)->IsAPTCA();
 }
-#endif // defined(FEATURE_APTCA) || defined(FEATURE_CORESYSTEM)
 
 void DECLSPEC_NORETURN Assembly::ThrowTypeLoadException(LPCUTF8 pszFullName, UINT resIDWhy)
 {
diff --git a/src/vm/classnames.h b/src/vm/classnames.h
index 47f1fecdec..6b10da1e27 100644
--- a/src/vm/classnames.h
+++ b/src/vm/classnames.h
@@ -165,11 +165,9 @@
 
 #define g_SecuritySafeCriticalAttribute "System.Security.SecuritySafeCriticalAttribute"
 
-#if defined(FEATURE_APTCA) || defined(FEATURE_CORESYSTEM)
 #define g_SecurityAPTCA "System.Security.AllowPartiallyTrustedCallersAttribute"
 #define g_SecurityPartialTrustVisibilityLevel "System.Security.PartialTrustVisibilityLevel"
 #define g_PartialTrustVisibilityLevel "PartialTrustVisibilityLevel"
-#endif // defined(FEATURE_APTCA) || defined(FEATURE_CORESYSTEM)
 
 #define g_ReferenceAssemblyAttribute "System.Runtime.CompilerServices.ReferenceAssemblyAttribute"
 
diff --git a/src/vm/comutilnative.cpp b/src/vm/comutilnative.cpp
index 41655cb5b0..0ef7460d37 100644
--- a/src/vm/comutilnative.cpp
+++ b/src/vm/comutilnative.cpp
@@ -1542,12 +1542,6 @@ void QCALLTYPE Buffer::MemMove(void *dst, void *src, size_t length)
 {
     QCALL_CONTRACT;
 
-#if defined(FEATURE_CORECLR) && !defined(FEATURE_CORESYSTEM)
-    // Callers of memcpy do expect and handle access violations in some scenarios.
-    // Access violations in the runtime dll are turned into fail fast by the vector exception handler by default.
-    // We need to supress this behavior for CoreCLR using AVInRuntimeImplOkayHolder because of memcpy is statically linked in.
-    AVInRuntimeImplOkayHolder avOk;
-#endif
 
     memmove(dst, src, length);
 }
diff --git a/src/vm/dllimport.cpp b/src/vm/dllimport.cpp
index b7989e92bc..d2d8c96694 100644
--- a/src/vm/dllimport.cpp
+++ b/src/vm/dllimport.cpp
@@ -6606,9 +6606,6 @@ static HMODULE LocalLoadLibraryHelper( LPCWSTR name, DWORD flags, LoadLibErrorTr
 #ifndef FEATURE_PAL
 
     if ((flags & 0xFFFFFF00) != 0
-#ifndef FEATURE_CORESYSTEM
-        && NDirect::SecureLoadLibrarySupported()
-#endif // !FEATURE_CORESYSTEM
         )
     {
         hmod = CLRLoadLibraryEx(name, NULL, flags & 0xFFFFFF00);
@@ -6661,62 +6658,6 @@ static HMODULE LocalLoadLibraryDirectHelper(LPCWSTR name, DWORD flags, LoadLibEr
 }
 
 
-#if !defined(FEATURE_CORESYSTEM)
-
-#define NATIVE_DLL(d) L#d, L#d W(".dll")
-
-const LPCWSTR wellKnownModules[] =
-{
-    NATIVE_DLL(advapi32),
-    NATIVE_DLL(gdi32),
-    NATIVE_DLL(gdiplus),
-    NATIVE_DLL(kernel32),
-    NATIVE_DLL(mscoree),
-    NATIVE_DLL(ole32),
-    NATIVE_DLL(shfolder),
-    NATIVE_DLL(user32),
-    NATIVE_DLL(version)
-};
-
-BOOL CompareLibNames (UPTR val1, UPTR val2)
-{
-    CONTRACTL {
-        MODE_ANY;
-        NOTHROW;
-        GC_NOTRIGGER;
-    }
-    CONTRACTL_END;
-
-    LPCWSTR wszStr1 = (LPCWSTR)(val1 << 1);
-    LPCWSTR wszStr2 = (LPCWSTR)val2;
-
-    if (SString::_wcsicmp(wszStr1, wszStr2) == 0)
-        return TRUE;
-
-    return FALSE;
-}
-
-PtrHashMap * NDirect::s_pWellKnownNativeModules  = NULL;
-bool         NDirect::s_fSecureLoadLibrarySupported = false;
-
-HINSTANCE NDirect::CheckForWellKnownModules(LPCWSTR wszLibName, LoadLibErrorTracker *pErrorTracker)
-{
-    STANDARD_VM_CONTRACT;
-
-    ModuleHandleHolder hMod;
-    ULONG hash = HashiString(wszLibName);
-    LPCWSTR     wszName = NULL;
-    wszName = (LPCWSTR) s_pWellKnownNativeModules->LookupValue((UPTR) hash, (LPVOID)wszLibName);
-
-    if (wszName != (LPCWSTR)INVALIDENTRY)
-    {
-        hMod = LocalLoadLibraryHelper(wszLibName, 0, pErrorTracker);
-    }
-
-    return hMod.Extract();
-}
-
-#endif  // !FEATURE_CORESYSTEM
 
 #define TOLOWER(a) (((a) >= W('A') && (a) <= W('Z')) ? (W('a') + (a - W('A'))) : (a))
 #define TOHEX(a)   ((a)>=10 ? W('a')+(a)-10 : W('0')+(a))
@@ -7006,9 +6947,6 @@ HINSTANCE NDirect::LoadLibraryModule(NDirectMethodDesc * pMD, LoadLibErrorTracke
        return hmod.Extract();
     }
 
-#if !defined(FEATURE_CORESYSTEM)
-    hmod = CheckForWellKnownModules(wszLibName, pErrorTracker);
-#endif
 
 #ifdef FEATURE_PAL
     // In the PAL version of CoreCLR, the CLR module itself exports the functionality
@@ -7020,7 +6958,7 @@ HINSTANCE NDirect::LoadLibraryModule(NDirectMethodDesc * pMD, LoadLibErrorTracke
         hmod = GetCLRModule();
 #endif // FEATURE_PAL
 
-#if defined(FEATURE_CORESYSTEM) && !defined(PLATFORM_UNIX)
+#if !defined(PLATFORM_UNIX)
     if (hmod == NULL)
     {
         // Try to go straight to System32 for Windows API sets. This is replicating quick check from
diff --git a/src/vm/dllimport.h b/src/vm/dllimport.h
index b393bf6cdd..a989af35ff 100644
--- a/src/vm/dllimport.h
+++ b/src/vm/dllimport.h
@@ -141,20 +141,6 @@ private:
     static HMODULE LoadLibraryModuleViaHost(NDirectMethodDesc * pMD, AppDomain* pDomain, const wchar_t* wszLibName);
 #endif //defined(FEATURE_HOST_ASSEMBLY_RESOLVER)
 
-#if !defined(FEATURE_CORESYSTEM)
-    static HINSTANCE    CheckForWellKnownModules(LPCWSTR wszLibName, LoadLibErrorTracker *pErrorTracker);
-    static PtrHashMap   *s_pWellKnownNativeModules;
-
-    // Indicates if the OS supports the new secure LoadLibraryEx flags introduced in KB2533623
-    static bool         s_fSecureLoadLibrarySupported;
-
-public:
-    static bool SecureLoadLibrarySupported()
-    {
-        LIMITED_METHOD_CONTRACT;
-        return s_fSecureLoadLibrarySupported;
-    }
-#endif // !FEATURE_CORESYSTEM
 };
 
 //----------------------------------------------------------------
diff --git a/src/vm/domainfile.cpp b/src/vm/domainfile.cpp
index bfb69cdd48..9a3b902e1c 100644
--- a/src/vm/domainfile.cpp
+++ b/src/vm/domainfile.cpp
@@ -3837,113 +3837,7 @@ bool DomainAssembly::GetDebuggingOverrides(DWORD *pdwFlags)
     }
     CONTRACTL_END;
 
-#if defined(DEBUGGING_SUPPORTED) && !defined(FEATURE_CORESYSTEM)
-    // TODO FIX in V5.0
-    // Any touch of the file system is relatively expensive even in the warm case. 
-    // 
-    // Ideally we remove the .INI feature completely (if we need something put it in the .exe.config file)
-    // 
-    // However because of compatibility concerns, we won't do this until the next side-by-side release
-    // In the mean time don't check in the case where we have already loaded the NGEN image, as the
-    // JIT overrides don't mean anything in that case as we won't be jitting anyway.  
-    // This avoids doing these probes for framework DLLs right away.
-    if (GetFile()->HasNativeImage())
-        return false;
-
-    _ASSERTE(pdwFlags);
-
-    bool fHasBits = false;
-    WCHAR *pFileName = NULL;
-    HRESULT hr = S_OK;
-    UINT cbExtOrValue = 4;
-    WCHAR *pTail = NULL;
-    size_t len = 0;
-    WCHAR *lpFileName = NULL;
-
-    const WCHAR *wszFileName = GetFile()->GetPath();
-
-    if (wszFileName == NULL)
-    {
-        return false;
-    }
-
-    // lpFileName is a copy of the original, and will be edited.
-    CQuickBytes qb;
-    len = wcslen(wszFileName);
-    size_t cchlpFileName = (len + 1);
-    lpFileName = (WCHAR*)qb.AllocThrows(cchlpFileName * sizeof(WCHAR));
-    wcscpy_s(lpFileName, cchlpFileName, wszFileName);
-
-    pFileName = wcsrchr(lpFileName, W('\\'));
-
-    if (pFileName == NULL)
-    {
-        pFileName = lpFileName;
-    }
-
-    if (*pFileName == W('\\'))
-    {
-        pFileName++; //move the pointer past the last '\'
-    }
-
-    _ASSERTE(wcslen(W(".INI")) == cbExtOrValue);
-
-    if (pFileName == NULL || (pTail=wcsrchr(pFileName, W('.'))) == NULL || (wcslen(pTail)<cbExtOrValue))
-    {
-        return false;
-    }
-
-    wcscpy_s(pTail, cchlpFileName - (pTail - lpFileName), W(".INI"));
-
-    // Win2K has a problem if multiple processes call GetPrivateProfile* on the same
-    // non-existent .INI file simultaneously.  The OS livelocks in the kernel (i.e.
-    // outside of user space) and remains there at full CPU for several minutes.  Then
-    // it breaks out.  Here is our work-around, while we pursue a fix in a future
-    // version of the OS.
-    if (WszGetFileAttributes(lpFileName) == INVALID_FILE_ATTRIBUTES)
-        return false;
-
-    // Having modified the filename, we use the full path
-    // to actually get the file.
-    if ((cbExtOrValue=WszGetPrivateProfileInt(DE_INI_FILE_SECTION_NAME,
-                                              DE_INI_FILE_KEY_TRACK_INFO,
-                                              INVALID_INI_INT,
-                                              lpFileName)) != INVALID_INI_INT)
-    {
-        if (cbExtOrValue != 0)
-        {
-            *pdwFlags |= DACF_OBSOLETE_TRACK_JIT_INFO;
-        }
-        else
-        {
-            *pdwFlags &= (~DACF_OBSOLETE_TRACK_JIT_INFO);
-        }
-
-        fHasBits = true;
-    }
-
-    if ((cbExtOrValue=WszGetPrivateProfileInt(DE_INI_FILE_SECTION_NAME,
-                                              DE_INI_FILE_KEY_ALLOW_JIT_OPTS,
-                                              INVALID_INI_INT,
-                                              lpFileName)) != INVALID_INI_INT)
-    {
-        if (cbExtOrValue != 0)
-        {
-            *pdwFlags |= DACF_ALLOW_JIT_OPTS;
-        }
-        else
-        {
-            *pdwFlags &= (~DACF_ALLOW_JIT_OPTS);
-        }
-
-        fHasBits = true;
-    }
-
-    return fHasBits;
-
-#else  // DEBUGGING_SUPPORTED && !FEATURE_CORESYSTEM
     return false;
-#endif // DEBUGGING_SUPPORTED && !FEATURE_CORESYSTEM
 }
 
 
diff --git a/src/vm/dwreport.cpp b/src/vm/dwreport.cpp
index 5ae4f84de2..67a9fb66b2 100644
--- a/src/vm/dwreport.cpp
+++ b/src/vm/dwreport.cpp
@@ -127,13 +127,8 @@ public:
     operator HMODULE() { return hModule; }
 };
 
-#ifndef FEATURE_CORESYSTEM
-#define WER_MODULE_NAME_W WINDOWS_KERNEL32_DLLNAME_W
-typedef SimpleModuleHolder<WszGetModuleHandle, false> WerModuleHolder;
-#else
 #define WER_MODULE_NAME_W W("api-ms-win-core-windowserrorreporting-l1-1-0.dll")
 typedef SimpleModuleHolder<CLRLoadLibrary, true> WerModuleHolder;
-#endif
 
 //------------------------------------------------------------------------------
 // Description
@@ -216,13 +211,11 @@ BOOL RegisterOutOfProcessWatsonCallbacks()
     WCHAR wszDACName[] = MAIN_DAC_MODULE_NAME_W W(".dll");
     WerModuleHolder hWerModule(WER_MODULE_NAME_W);
 
-#ifdef FEATURE_CORESYSTEM
     if ((hWerModule == NULL) && !RunningOnWin8())
     {
         // If we are built for CoreSystemServer, but are running on Windows 7, we need to look elsewhere
         hWerModule = WerModuleHolder(W("Kernel32.dll"));
     }
-#endif
 
     if (hWerModule == NULL)
     {
@@ -264,15 +257,10 @@ BOOL RegisterOutOfProcessWatsonCallbacks()
                     LL_ERROR, 
                     "WATSON support: failed to register DAC dll with WerRegisterRuntimeExceptionModule");
 
-#ifdef FEATURE_CORESYSTEM
         // For CoreSys we *could* be running on a platform that doesn't have Watson proper 
         // (the APIs might exist but they just fail).  
         // WerRegisterRuntimeExceptionModule may return E_NOIMPL.
         return TRUE;
-#else // FEATURE_CORESYSTEM
-       _ASSERTE(! "WATSON support: failed to register DAC dll with WerRegisterRuntimeExceptionModule");
-        return FALSE;
-#endif // FEATURE_CORESYSTEM
     }
 
     STRESS_LOG0(LF_STARTUP, 
diff --git a/src/vm/ecalllist.h b/src/vm/ecalllist.h
index ba05e99543..a5031f3e8b 100644
--- a/src/vm/ecalllist.h
+++ b/src/vm/ecalllist.h
@@ -291,9 +291,6 @@ FCFuncStart(gEnvironmentFuncs)
     FCFuncElement("GetCommandLineArgsNative", SystemNative::GetCommandLineArgs)
     FCFuncElement("get_CurrentProcessorNumber", SystemNative::GetCurrentProcessorNumber)
 
-#if defined(FEATURE_COMINTEROP) && !defined(FEATURE_CORESYSTEM)
-    QCFuncElement("WinRTSupported", SystemNative::WinRTSupported)
-#endif // FEATURE_COMINTEROP
     FCFuncElementSig("FailFast", &gsig_SM_Str_RetVoid, SystemNative::FailFast)
     FCFuncElementSig("FailFast", &gsig_SM_Str_Exception_RetVoid, SystemNative::FailFastWithException)
 #ifndef FEATURE_CORECLR
diff --git a/src/vm/eventreporter.cpp b/src/vm/eventreporter.cpp
index 567f4f5d51..6ef767c424 100644
--- a/src/vm/eventreporter.cpp
+++ b/src/vm/eventreporter.cpp
@@ -468,33 +468,8 @@ BOOL ShouldLogInEventLog()
     }
     CONTRACTL_END;
 
-#ifndef FEATURE_CORESYSTEM
-    // If the process is being debugged, don't log
-    if ((CORDebuggerAttached() || IsDebuggerPresent())
-#ifdef _DEBUG
-        // Allow debug to be able to break in
-        &&
-        CLRConfig::GetConfigValue(CLRConfig::INTERNAL_BreakOnUncaughtException) == 0
-#endif
-        )
-    {
-        return FALSE;
-    }
-
-    static LONG fOnce = 0;
-    if (fOnce == 1 || FastInterlockExchange(&fOnce, 1) == 1)
-    {
-        return FALSE;
-    }
-
-    if (CLRConfig::GetConfigValue(CLRConfig::EXTERNAL_logFatalError) == 0)
-        return FALSE;
-    else
-        return TRUE;
-#else
     // no event log on Apollo
     return FALSE;
-#endif //!FEATURE_CORESYSTEM
 }
 
 //---------------------------------------------------------------------------------------
diff --git a/src/vm/eventtrace.cpp b/src/vm/eventtrace.cpp
index 2bdd441a9a..fb5d9b0090 100644
--- a/src/vm/eventtrace.cpp
+++ b/src/vm/eventtrace.cpp
@@ -4310,26 +4310,6 @@ HRESULT ETW::CEtwTracer::Register()
 {
     WRAPPER_NO_CONTRACT;
 
-#ifndef FEATURE_CORESYSTEM
-    OSVERSIONINFO osVer;
-    osVer.dwOSVersionInfoSize = sizeof(OSVERSIONINFO);
-
-    if (GetOSVersion(&osVer) == FALSE) {
-        return HRESULT_FROM_WIN32(ERROR_NOT_SUPPORTED);
-    }
-    else if (osVer.dwMajorVersion < ETW_SUPPORTED_MAJORVER) {
-        return HRESULT_FROM_WIN32(ERROR_NOT_SUPPORTED);
-    }
-
-    // if running on OS < Longhorn, skip registration unless reg key is set
-    // since ETW reg is expensive (in both time and working set) on older OSes
-    if (osVer.dwMajorVersion < ETW_ENABLED_MAJORVER && !g_fEnableETW && !CLRConfig::GetConfigValue(CLRConfig::EXTERNAL_PreVistaETWEnabled))
-        return HRESULT_FROM_WIN32(ERROR_NOT_SUPPORTED);
-
-    // If running on OS >= Longhorn, skip registration if ETW is not enabled
-    if (osVer.dwMajorVersion >= ETW_ENABLED_MAJORVER && !g_fEnableETW && !CLRConfig::GetConfigValue(CLRConfig::EXTERNAL_VistaAndAboveETWEnabled))
-        return HRESULT_FROM_WIN32(ERROR_NOT_SUPPORTED);
-#endif
 
     EventRegisterMicrosoft_Windows_DotNETRuntime();
     EventRegisterMicrosoft_Windows_DotNETRuntimePrivate();
diff --git a/src/vm/excep.cpp b/src/vm/excep.cpp
index 78a8f0e6eb..262414cd6c 100644
--- a/src/vm/excep.cpp
+++ b/src/vm/excep.cpp
@@ -4175,18 +4175,6 @@ void RaiseFailFastExceptionOnWin7(PEXCEPTION_RECORD pExceptionRecord, PCONTEXT p
     LIMITED_METHOD_CONTRACT;
     _ASSERTE(RunningOnWin7());
 
-#ifndef FEATURE_CORESYSTEM
-    typedef void (WINAPI * RaiseFailFastExceptionFnPtr)(PEXCEPTION_RECORD, PCONTEXT, DWORD);
-    RaiseFailFastExceptionFnPtr RaiseFailFastException;
-
-    HINSTANCE hKernel32 = WszGetModuleHandle(WINDOWS_KERNEL32_DLLNAME_W);
-    if (hKernel32 == NULL)
-        return;
-
-    RaiseFailFastException = (RaiseFailFastExceptionFnPtr)GetProcAddress(hKernel32, "RaiseFailFastException");
-    if (RaiseFailFastException == NULL)
-        return;
-#endif
 
     // enable preemptive mode before call into OS to allow runtime suspend to finish
     GCX_PREEMP();
diff --git a/src/vm/gcenv.os.cpp b/src/vm/gcenv.os.cpp
index 52789b835c..f61d042092 100644
--- a/src/vm/gcenv.os.cpp
+++ b/src/vm/gcenv.os.cpp
@@ -71,9 +71,7 @@ bool GCToOSInterface::SetCurrentThreadIdealAffinity(GCThreadAffinity* affinity)
 
     bool success = true;
 
-#if !defined(FEATURE_CORESYSTEM)
-    SetThreadIdealProcessor(GetCurrentThread(), (DWORD)affinity->Processor);
-#elif !defined(FEATURE_PAL)
+#if !defined(FEATURE_PAL)
     PROCESSOR_NUMBER proc;
 
     if (affinity->Group != -1)
diff --git a/src/vm/i386/cgenx86.cpp b/src/vm/i386/cgenx86.cpp
index 528629c3a2..1c6737b259 100644
--- a/src/vm/i386/cgenx86.cpp
+++ b/src/vm/i386/cgenx86.cpp
@@ -94,65 +94,7 @@ void ClearRegDisplayArgumentAndScratchRegisters(REGDISPLAY * pRD)
 //
 BOOL Runtime_Test_For_SSE2()
 {
-#ifdef FEATURE_CORESYSTEM
     return TRUE;
-#else
-
-    BOOL result = IsProcessorFeaturePresent(PF_XMMI64_INSTRUCTIONS_AVAILABLE);
-
-    if (result == FALSE)
-        return FALSE;
-
-    // **********************************************************************
-    // ***                                                                ***
-    // ***   IMPORTANT NOTE:                                              ***
-    // ***                                                                ***
-    // ***     All of these RunningOnXXX APIs return true when            ***
-    // ***     the OS that you are running on is that OS or later.        ***
-    // ***     For example RunningOnWin2003() will return true            ***
-    // ***     when you are running on Win2k3, Vista, Win7 or later.      ***
-    // ***                                                                ***
-    // **********************************************************************
-
-
-    // Windows 7 and later should alwys be using SSE2 instructions
-    //  this is true for both for native and Wow64
-    //
-    if (RunningOnWin7())
-        return TRUE;
-
-    if (RunningInWow64())
-    {
-        // There is an issue with saving/restoring the SSE2 registers under wow64 
-        // So we figure out if we are running on an impacted OS and Service Pack level
-        //     See DevDiv Bugs 89587 for the wow64 bug.
-        //
-
-        _ASSERTE(ExOSInfoAvailable());  // This is always available on Vista and later
-
-        //
-        // The issue is fixed in Windows Server 2008 or Vista/SP1
-        //
-        // It is not fixed in Vista/RTM, so check for that case
-        // 
-        if ((ExOSInfoRunningOnServer() == FALSE))
-        {
-            OSVERSIONINFOEX osvi;
-
-            ZeroMemory(&osvi, sizeof(OSVERSIONINFOEX));
-            osvi.dwOSVersionInfoSize = sizeof(OSVERSIONINFOEX);
-            osvi.wServicePackMajor = 0;
-
-            DWORDLONG dwlConditionMask = 0;
-            VER_SET_CONDITION( dwlConditionMask, CLR_VER_SERVICEPACKMAJOR, VER_EQUAL);
-                
-            if (VerifyVersionInfo(&osvi, CLR_VER_SERVICEPACKMAJOR, dwlConditionMask))
-                result = FALSE;
-        }
-    }
-
-    return result;
-#endif
 }
 
 //---------------------------------------------------------------
diff --git a/src/vm/i386/stublinkerx86.cpp b/src/vm/i386/stublinkerx86.cpp
index 63b9e87367..61577463c6 100644
--- a/src/vm/i386/stublinkerx86.cpp
+++ b/src/vm/i386/stublinkerx86.cpp
@@ -3871,48 +3871,6 @@ VOID StubLinkerCPU::EmitDisable(CodeLabel *pForwardRef, BOOL fCallIn, X86Reg Thr
     // jnz RarePath
     X86EmitCondJump(pForwardRef, X86CondCode::kJNZ);
 
-#if defined(FEATURE_COMINTEROP) && !defined(FEATURE_CORESYSTEM)
-    // If we are checking whether the current thread holds the loader lock, vector
-    // such cases to the rare disable pathway, where we can check again.
-    if (fCallIn && ShouldCheckLoaderLock())
-    {
-        X86EmitPushReg(kEAX);
-        X86EmitPushReg(kEDX);
-
-        if (ThreadReg == kECX)
-            X86EmitPushReg(kECX);
-
-        // BOOL AuxUlibIsDLLSynchronizationHeld(BOOL *IsHeld)
-        //
-        // So we need to be sure that both the return value and the passed BOOL are both TRUE.
-        // If either is FALSE, then the call failed or the lock is not held.  Either way, the
-        // probe should not fire.
-
-        X86EmitPushReg(kEDX);               // BOOL temp
-        Emit8(0x54);                        // push ESP because arg is &temp
-        X86EmitCall(NewExternalCodeLabel((LPVOID) AuxUlibIsDLLSynchronizationHeld), 0);
-
-        // callee has popped.
-        X86EmitPopReg(kEDX);                // recover temp
-
-        CodeLabel   *pPopLabel = NewCodeLabel();
-
-        Emit16(0xc085);                     // test eax, eax
-        X86EmitCondJump(pPopLabel, X86CondCode::kJZ);
-
-        Emit16(0xd285);                     // test edx, edx
-
-        EmitLabel(pPopLabel);               // retain the conditional flags across the pops
-
-        if (ThreadReg == kECX)
-            X86EmitPopReg(kECX);
-
-        X86EmitPopReg(kEDX);
-        X86EmitPopReg(kEAX);
-
-        X86EmitCondJump(pForwardRef, X86CondCode::kJNZ);
-    }
-#endif
 
 #ifdef _DEBUG
     if (ThreadReg != kECX)
diff --git a/src/vm/interoputil.cpp b/src/vm/interoputil.cpp
index 6a0fbded12..b367dff45f 100644
--- a/src/vm/interoputil.cpp
+++ b/src/vm/interoputil.cpp
@@ -2535,20 +2535,12 @@ HRESULT GetCLSIDFromProgID(__in_z WCHAR *strProgId, GUID *pGuid)
     
     HRESULT     hr = S_OK;
 
-#ifdef FEATURE_CORESYSTEM
     LeaveRuntimeHolderNoThrow lrh((size_t)CLSIDFromProgID);
-#else
-    LeaveRuntimeHolderNoThrow lrh((size_t)CLSIDFromProgIDEx);
-#endif
     hr = lrh.GetHR();
     if (FAILED(hr))
         return hr;
 
-#ifdef FEATURE_CORESYSTEM
     return CLSIDFromProgID(strProgId, pGuid);
-#else
-    return CLSIDFromProgIDEx(strProgId, pGuid);
-#endif
 }
 #endif // FEATURE_CLASSIC_COMINTEROP
 
diff --git a/src/vm/jithelpers.cpp b/src/vm/jithelpers.cpp
index 7b9389d5b6..c96b68ba63 100644
--- a/src/vm/jithelpers.cpp
+++ b/src/vm/jithelpers.cpp
@@ -540,7 +540,7 @@ ftype BankersRound(ftype value)
     if ((value -(integerPart +0.5)) == 0.0)
     {
         // round to even 
-#if defined(_TARGET_ARM_) && defined(FEATURE_CORESYSTEM)
+#if defined(_TARGET_ARM_)
         // @ARMTODO: On ARM when building on CoreSystem (where we link against the system CRT) an attempt to
         // use fmod(float, float) fails to link (apparently this is converted to a reference to fmodf, which
         // is not included in the system CRT). Use the double version instead.
diff --git a/src/vm/jitinterface.cpp b/src/vm/jitinterface.cpp
index e0c714363d..f710dcf3eb 100644
--- a/src/vm/jitinterface.cpp
+++ b/src/vm/jitinterface.cpp
@@ -12804,7 +12804,6 @@ PCODE UnsafeJitFunction(MethodDesc* ftn, COR_ILMETHOD_DECODER* ILHeader, CORJIT_
             "Jitted Entry at" FMT_ADDR "method %s::%s %s\n", DBG_ADDR(nativeEntry),
              ftn->m_pszDebugClassName, ftn->m_pszDebugMethodName, ftn->m_pszDebugMethodSignature));
 
-#if defined(FEATURE_CORESYSTEM)
 
 #ifdef _DEBUG
         LPCUTF8 pszDebugClassName = ftn->m_pszDebugClassName;
@@ -12819,7 +12818,6 @@ PCODE UnsafeJitFunction(MethodDesc* ftn, COR_ILMETHOD_DECODER* ILHeader, CORJIT_
 
         //DbgPrintf("Jitted Entry at" FMT_ADDR "method %s::%s %s size %08x\n", DBG_ADDR(nativeEntry),
         //          pszDebugClassName, pszDebugMethodName, pszDebugMethodSignature, sizeOfCode);
-#endif
 
         ClrFlushInstructionCache(nativeEntry, sizeOfCode); 
         ret = (PCODE)nativeEntry;
diff --git a/src/vm/methodtablebuilder.cpp b/src/vm/methodtablebuilder.cpp
index 303edc4683..68148d7683 100644
--- a/src/vm/methodtablebuilder.cpp
+++ b/src/vm/methodtablebuilder.cpp
@@ -5172,7 +5172,6 @@ void MethodTableBuilder::SetSecurityFlagsOnMethod(bmtRTMethod* pParentMethod,
         pNewMD->SetRequiresLinktimeCheck();
     }
 
-#if defined(FEATURE_APTCA) || defined(FEATURE_CORESYSTEM) 
     // All public methods on public types will do a link demand of
     // full trust, unless AllowUntrustedCaller attribute is set
     if (
@@ -5200,7 +5199,6 @@ void MethodTableBuilder::SetSecurityFlagsOnMethod(bmtRTMethod* pParentMethod,
                 pNewMD->SetRequiresLinktimeCheck();
         }
     }
-#endif //  defined(FEATURE_APTCA) || defined(FEATURE_CORESYSTEM)
 
     // If it's a delegate BeginInvoke, we need to do a HostProtection check for synchronization
     if(!pNewMD->RequiresLinktimeCheck() && IsDelegate())
diff --git a/src/vm/notifyexternals.cpp b/src/vm/notifyexternals.cpp
index df1cce4e5b..1d69edf0b8 100644
--- a/src/vm/notifyexternals.cpp
+++ b/src/vm/notifyexternals.cpp
@@ -30,32 +30,6 @@ BOOL ShouldCheckLoaderLock(BOOL fForMDA /*= TRUE*/)
     }
     CONTRACTL_END;
     
-#ifdef FEATURE_CORESYSTEM
     // CoreSystem does not support this.
     return FALSE;
-#else
-    // Because of how C++ generates code, we must use default initialization to
-    // 0 here.  Any explicit initialization will result in thread-safety problems.
-    static BOOL fInited;
-    static BOOL fShouldCheck;
-    static BOOL fShouldCheck_ForMDA;
-
-    if (VolatileLoad(&fInited) == FALSE)
-    {
-        fShouldCheck_ForMDA = FALSE;
-
-        fShouldCheck = AuxUlibInitialize();      // may fail
-
-#ifdef MDA_SUPPORTED
-        if (fShouldCheck)
-        {
-            MdaLoaderLock* pProbe = MDA_GET_ASSISTANT(LoaderLock);
-            if (pProbe)
-                fShouldCheck_ForMDA = TRUE;
-        }
-#endif // MDA_SUPPORTED
-        VolatileStore(&fInited, TRUE);
-    }
-    return (fForMDA ? fShouldCheck_ForMDA : fShouldCheck);
-#endif // FEATURE_CORESYSTEM
 }
diff --git a/src/vm/runtimecallablewrapper.cpp b/src/vm/runtimecallablewrapper.cpp
index 359b6896bc..29999a7dad 100644
--- a/src/vm/runtimecallablewrapper.cpp
+++ b/src/vm/runtimecallablewrapper.cpp
@@ -742,7 +742,6 @@ IUnknown *AppXComClassFactory::CreateInstanceInternal(IUnknown *pOuter, BOOL *pf
     
     HRESULT hr;
 
-#ifdef FEATURE_CORESYSTEM
     // This works around a bug in the Windows 7 loader that prevents us from loading the
     // forwarder for this function
     typedef HRESULT (*CoCreateInstanceFromAppFnPtr) (REFCLSID rclsid, IUnknown *punkOuter, DWORD dwClsCtx,
@@ -763,7 +762,6 @@ IUnknown *AppXComClassFactory::CreateInstanceInternal(IUnknown *pOuter, BOOL *pf
         _ASSERTE(false);
         IfFailThrow(E_FAIL);
     }
-#endif
 
     LeaveRuntimeHolder lrh((size_t)CoCreateInstanceFromApp);
     
diff --git a/src/vm/securitydeclarative.cpp b/src/vm/securitydeclarative.cpp
index e0aff16ddd..10abd5500b 100644
--- a/src/vm/securitydeclarative.cpp
+++ b/src/vm/securitydeclarative.cpp
@@ -841,7 +841,6 @@ LinktimeCheckReason SecurityDeclarative::GetLinktimeCheckReason(MethodDesc *pMD,
 
     LinktimeCheckReason reason = LinktimeCheckReason_None;
 
-#if defined(FEATURE_APTCA) || defined(FEATURE_CORESYSTEM)
     ModuleSecurityDescriptor *pMSD = ModuleSecurityDescriptor::GetModuleSecurityDescriptor(pMD->GetAssembly());
 
     // If the method does not allow partially trusted callers, then the check is because we need to ensure all
@@ -850,7 +849,6 @@ LinktimeCheckReason SecurityDeclarative::GetLinktimeCheckReason(MethodDesc *pMD,
     {
         reason |= LinktimeCheckReason_AptcaCheck;
     }
-#endif // defined(FEATURE_APTCA) || defined(FEATURE_CORESYSTEM)
 
     //
     // If the method has a LinkDemand on it for either CAS or non-CAS permissions, get those and set the
diff --git a/src/vm/securitymeta.cpp b/src/vm/securitymeta.cpp
index ff286ddb68..cc2f10a477 100644
--- a/src/vm/securitymeta.cpp
+++ b/src/vm/securitymeta.cpp
@@ -1786,7 +1786,6 @@ VOID ModuleSecurityDescriptor::Fixup(DataImage *image)
 }
 #endif
 
-#if defined(FEATURE_APTCA) || defined(FEATURE_CORESYSTEM)
 
 //---------------------------------------------------------------------------------------
 //
@@ -1829,7 +1828,6 @@ TokenSecurityDescriptorFlags ParseAptcaAttribute(const BYTE *pbAptcaBlob, DWORD
     return aptcaFlags;
 }
 
-#endif // defined(FEATURE_APTCA) || defined(FEATURE_CORESYSTEM)
 
 //---------------------------------------------------------------------------------------
 //
@@ -1935,7 +1933,6 @@ TokenSecurityDescriptorFlags TokenSecurityDescriptor::ReadSecurityAttributes(IMD
             szAttributeNamespace != NULL &&
             strcmp(g_SecurityNS, szAttributeNamespace) == 0)
         {
-#if defined(FEATURE_APTCA) || defined(FEATURE_CORESYSTEM)
             if (strcmp(g_SecurityAPTCA + sizeof(g_SecurityNS), szAttributeName) == 0)
             {
                 // Check the visibility parameter
@@ -1951,7 +1948,6 @@ TokenSecurityDescriptorFlags TokenSecurityDescriptor::ReadSecurityAttributes(IMD
                 flags |= aptcaFlags;
             }
             else
-#endif // defined(FEATURE_APTCA) || defined(FEATURE_CORESYSTEM)
             if (strcmp(g_SecurityCriticalAttribute + sizeof(g_SecurityNS), szAttributeName) == 0)
             {
                 flags |= TokenSecurityDescriptorFlags_Critical;
diff --git a/src/vm/securitymeta.h b/src/vm/securitymeta.h
index d78b7bde54..dae8f733e9 100644
--- a/src/vm/securitymeta.h
+++ b/src/vm/securitymeta.h
@@ -641,10 +641,8 @@ public:
     inline BOOL CanTransparentCodeSkipVerification();
 #endif // !FEATURE_CORECLR
 
-#if defined(FEATURE_APTCA) || defined(FEATURE_CORESYSTEM)
     // Does the assembly allow partially trusted callers
     inline BOOL IsAPTCA();
-#endif // defined(FEATURE_APTCA) || defined(FEATURE_CORESYSTEM)
 
 #ifndef FEATURE_CORECLR
     BOOL AssemblyVersionRequiresLegacyTransparency();
diff --git a/src/vm/securitytransparentassembly.cpp b/src/vm/securitytransparentassembly.cpp
index be13cab612..3f3bef6479 100644
--- a/src/vm/securitytransparentassembly.cpp
+++ b/src/vm/securitytransparentassembly.cpp
@@ -1443,12 +1443,10 @@ public:
 
         ModuleSecurityDescriptorFlags moduleFlags = ModuleSecurityDescriptorFlags_None;
 
-#if defined(FEATURE_APTCA) || defined(FEATURE_CORESYSTEM)
         if (tokenFlags & TokenSecurityDescriptorFlags_APTCA)
         {
             moduleFlags |= ModuleSecurityDescriptorFlags_IsAPTCA;
         }
-#endif // defined(FEATURE_APTCA) || defined(FEATURE_CORESYSTEM)
 
         if (tokenFlags & TokenSecurityDescriptorFlags_Critical)
         {
@@ -1618,12 +1616,10 @@ public:
         ModuleSecurityDescriptorFlags moduleFlags = ModuleSecurityDescriptorFlags_None;
         bool fShouldBeOpportunisticallyCritical = true;
 
-#if defined(FEATURE_APTCA) || defined(FEATURE_CORESYSTEM)
         if (tokenFlags & TokenSecurityDescriptorFlags_APTCA)
         {
             moduleFlags |= ModuleSecurityDescriptorFlags_IsAPTCA;
         }
-#endif // defined(FEATURE_APTCA) || defined(FEATURE_CORESYSTEM)
 
         if (tokenFlags & TokenSecurityDescriptorFlags_Transparent)
         {
diff --git a/src/vm/util.cpp b/src/vm/util.cpp
index 2cf6f7f31c..28546642a1 100644
--- a/src/vm/util.cpp
+++ b/src/vm/util.cpp
@@ -369,20 +369,6 @@ void NPrintToHandleA(HANDLE Handle, const char *pszString, size_t BytesToWrite)
         DWORD dwChunkToWrite = (DWORD) min(BytesToWrite, maxWriteFileSize);
         // No CharNextExA on CoreSystem, we just assume no multi-byte characters (this code path shouldn't be
         // used in the production codepath for currently supported CoreSystem based products anyway).
-#ifndef FEATURE_CORESYSTEM
-        if (dwChunkToWrite < BytesToWrite) {
-            break;
-            // must go by char to find biggest string that will fit, taking DBCS chars into account
-            //dwChunkToWrite = 0;
-            //const char *charNext = pszString;
-            //while (dwChunkToWrite < maxWriteFileSize-2 && charNext) {
-            //    charNext = CharNextExA(0, pszString+dwChunkToWrite, 0);
-            //    dwChunkToWrite = (DWORD)(charNext - pszString);
-            //}
-            //if (dwChunkToWrite == 0)
-            //    break;
-        }
-#endif // !FEATURE_CORESYSTEM
 
         // Try to write to handle.  If this is not a CUI app, then this is probably
         // not going to work unless the dev took special pains to set their own console
@@ -2243,78 +2229,11 @@ DWORD GetLogicalCpuCountFallback()
 
         if(LogicalNum > 1) 
         {
-#ifdef FEATURE_CORESYSTEM
             // CoreSystem doesn't expose GetProcessAffinityMask or SetProcessAffinityMask or anything
             // functionally equivalent. Just assume 1:1 mapping if we get here (in reality we shouldn't since
             // all CoreSystems support GetLogicalProcessorInformation so GetLogicalCpuCountFromOS should have
             // taken care of everything.
             goto fDone;
-#else // FEATURE_CORESYSTEM
-            HANDLE hCurrentProcessHandle;
-            DWORD_PTR  dwProcessAffinity;
-            DWORD_PTR  dwSystemAffinity;
-            DWORD_PTR  dwAffinityMask;
-
-            // Calculate the appropriate  shifts and mask based on the
-            // number of logical processors.
-
-            BYTE i = 1, PHY_ID_MASK  = 0xFF, PHY_ID_SHIFT = 0;
-            while (i < LogicalNum)
-            {
-                i *= 2;
-                PHY_ID_MASK  <<= 1;
-                PHY_ID_SHIFT++;
-            }
-            hCurrentProcessHandle = GetCurrentProcess();  
-
-            GetProcessAffinityMask(hCurrentProcessHandle, &dwProcessAffinity, &dwSystemAffinity);
-
-            // Check if available process affinity mask is equal to the available system affinity mask
-            // If the masks are equal, then all the processors the OS utilizes are available to the 
-            // application.
-
-            if (dwProcessAffinity != dwSystemAffinity)
-            {
-                retVal = 0;          
-                goto fDone;
-            }
-
-            dwAffinityMask = 1;
-
-            // loop over all processors, running APIC ID retrieval code starting
-            // with the first one by setting process affinity.
-            while (dwAffinityMask != 0 && dwAffinityMask <= dwProcessAffinity)
-            {
-                // Check if this CPU is available
-                if (dwAffinityMask & dwProcessAffinity)
-                {
-                    if (SetProcessAffinityMask(hCurrentProcessHandle, dwAffinityMask))  
-                    {
-                        BYTE APIC_ID, LOG_ID, PHY_ID;
-                        __SwitchToThread(0, CALLER_LIMITS_SPINNING); // Give OS time to switch CPU
-
-                        getextcpuid(0,1, buffer);  //call cpuid with EAX=1
-
-                        APIC_ID = (dwBuffer[1] & INITIAL_APIC_ID_BITS) >> 24;
-                        LOG_ID  = APIC_ID & ~PHY_ID_MASK;
-                        PHY_ID  = APIC_ID >> PHY_ID_SHIFT;
-                        if (LOG_ID != 0)   
-                        lProcCounter++;
-                    }
-                }
-                dwAffinityMask = dwAffinityMask << 1;
-            }
-            // Reset the processor affinity
-
-            SetProcessAffinityMask(hCurrentProcessHandle, dwProcessAffinity);
-
-            // Check if HT is enabled on all the processors
-            if(lProcCounter > 0 && (lProcCounter == (DWORD)(PhysicalNum / LogicalNum)))
-            {
-                retVal = lProcCounter;
-                goto fDone;
-            }
-#endif // FEATURE_CORESYSTEM
         }
     }   
 fDone:
diff --git a/src/vm/win32threadpool.cpp b/src/vm/win32threadpool.cpp
index e8a05c383f..90be10a99b 100644
--- a/src/vm/win32threadpool.cpp
+++ b/src/vm/win32threadpool.cpp
@@ -495,11 +495,7 @@ void ThreadpoolMgr::InitPlatformVariables()
         CONTRACT_VIOLATION(GCViolation|FaultViolation);
         hNtDll = CLRLoadLibrary(W("ntdll.dll"));
         _ASSERTE(hNtDll);
-#ifdef FEATURE_CORESYSTEM
         hCoreSynch = CLRLoadLibrary(W("api-ms-win-core-synch-l1-1-0.dll"));
-#else
-        hCoreSynch = CLRLoadLibrary(W("kernel32.dll"));
-#endif
         _ASSERTE(hCoreSynch);
     }
 
diff --git a/src/zap/zapimage.cpp b/src/zap/zapimage.cpp
index f39b8f8f54..347718a76c 100644
--- a/src/zap/zapimage.cpp
+++ b/src/zap/zapimage.cpp
@@ -1714,7 +1714,7 @@ void ZapImage::OutputTables()
 #if defined(FEATURE_PAL)
     // PAL library requires native image sections to align to page bounaries.
     SetFileAlignment(0x1000);
-#elif defined(_TARGET_ARM_) && defined(FEATURE_CORECLR) && defined(FEATURE_CORESYSTEM)
+#elif defined(_TARGET_ARM_) && defined(FEATURE_CORECLR)
     if (!IsReadyToRunCompilation())
     {
         // On ARM CoreSys builds, crossgen will use 4k file alignment, as requested by Phone perf team