--- a/b2g/app/nsBrowserApp.cpp
+++ b/b2g/app/nsBrowserApp.cpp
@@ -20,17 +20,16 @@
 #include <string.h>
 
 #include "nsCOMPtr.h"
 #include "nsIFile.h"
 #include "nsStringGlue.h"
 
 #ifdef XP_WIN
 // we want a wmain entry point
-#define XRE_DONT_SUPPORT_XPSP2 // See https://bugzil.la/1023941#c32
 #include "nsWindowsWMain.cpp"
 #if defined(_MSC_VER) && (_MSC_VER < 1900)
 #define snprintf _snprintf
 #endif
 #define strcasecmp _stricmp
 #endif
 
 #ifdef MOZ_WIDGET_GONK

--- a/ipc/ipdl/test/cxx/app/TestIPDL.cpp
+++ b/ipc/ipdl/test/cxx/app/TestIPDL.cpp
@@ -1,17 +1,16 @@
 /* This Source Code Form is subject to the terms of the Mozilla Public
  * License, v. 2.0. If a copy of the MPL was not distributed with this
  * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
 
 #include "nsXULAppAPI.h"
 
 #if defined(XP_WIN)
 #include <windows.h>
-#define XRE_DONT_SUPPORT_XPSP2 // this app doesn't ship
 #include "nsWindowsWMain.cpp"
 #endif
 
 int
 main(int argc, char** argv)
 {
     // the first argument specifies which IPDL test case/suite to load
     if (argc < 2)

--- a/js/xpconnect/shell/xpcshell.cpp
+++ b/js/xpconnect/shell/xpcshell.cpp
@@ -15,17 +15,16 @@
 #include "xpcshellMacUtils.h"
 #endif
 #ifdef XP_WIN
 #include <windows.h>
 #include <shlobj.h>
 
 // we want a wmain entry point
 #define XRE_DONT_PROTECT_DLL_LOAD
-#define XRE_DONT_SUPPORT_XPSP2 // xpcshell does not ship
 #define XRE_WANT_ENVIRON
 #include "nsWindowsWMain.cpp"
 #endif
 
 #ifdef MOZ_WIDGET_GTK
 #include <gtk/gtk.h>
 #endif
 

deleted file mode 100644
--- a/toolkit/xre/WindowsCrtPatch.h
+++ /dev/null
@@ -1,146 +0,0 @@
-/* -*- Mode: C++; tab-width: 40; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
-/* This Source Code Form is subject to the terms of the Mozilla Public
- * License, v. 2.0. If a copy of the MPL was not distributed with this
- * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
-
-/*
- * This file works around an incompatibility between Visual Studio 2013's
- * C Runtime DLL and Windows XP Service Pack 2.
- *
- * On XP SP2, msvcr120.dll fails to load, because it has a load-time dependency
- * on a kernel32 export named GetLogicalProcessorInformation, which is only
- * available in XP SP3 and newer. Microsoft has declared this to be by design.
- * See: https://connect.microsoft.com/VisualStudio/feedback/details/811379/
- *
- * The CRT calls GetLogicalProcessorInformation only from the concurrency
- * runtime, which our code does not use. A potential workaround is to 
- * static-link the CRT into all of our binaries and let the linker drop the
- * unused API calls. We don't want to take that approach, due to concerns
- * about binary bloat and jemalloc integration.
- *
- * Instead we hook the Windows loader and patch out the missing import.
- * We intercept ntdll!RtlImageNtHeader, which is a helper API called during
- * the DLL loading process. We walk the PE image and redirect the
- * GetLogicalProcessorInformation import to something benign like DebugBreak,
- * before the loader populates msvcr120.dll's import table.
- *
- * This is a fragile hack that only works if we can set up the hook before
- * Windows tries to load msvcr120.dll. This means that all .exe files:
- *  1) must static-link the CRT
- *  2) must delay-load anything with ties to msvcr120.dll (e.g. mozglue.dll)
- *  3) must not call malloc, because the linker would substitute our mozglue
- *     replacements, which leads to the CRT loading mozglue before main.
- * The remainder of our binaries can continue to dynamic-link the CRT.
- * Assertions enforce that our hooks are installed before msvcr120.dll.
- */
-
-#ifndef WindowsCrtPatch_h
-#define WindowsCrtPatch_h
-
-#include "nsWindowsDllInterceptor.h"
-#include "mozilla/WindowsVersion.h"
-
-namespace WindowsCrtPatch {
-
-mozilla::WindowsDllInterceptor NtdllIntercept;
-
-typedef PIMAGE_NT_HEADERS (NTAPI *RtlImageNtHeader_func)(HMODULE module);
-static RtlImageNtHeader_func stub_RtlImageNtHeader = 0;
-
-// A helper to simplify the use of Relative Virtual Addresses.
-template <typename T>
-class RVAPtr
-{
-public:
-  RVAPtr(HMODULE module, size_t rva)
-    : _ptr(reinterpret_cast<T*>(reinterpret_cast<char*>(module) + rva)) {}
-  operator T*() { return _ptr; }
-  T* operator ->() { return _ptr; }
-  T* operator ++() { return ++_ptr; }
-
-private:
-  T* _ptr;
-};
-
-void
-PatchModuleImports(HMODULE module, PIMAGE_NT_HEADERS headers)
-{
-  static const WORD MAGIC_DOS = 0x5a4d; // "MZ"
-  static const DWORD MAGIC_PE = 0x4550; // "PE\0\0"
-  RVAPtr<IMAGE_DOS_HEADER> dosStub(module, 0);
-
-  if (!module ||
-      !headers ||
-      dosStub->e_magic != MAGIC_DOS ||
-      headers != RVAPtr<IMAGE_NT_HEADERS>(module, dosStub->e_lfanew) ||
-      headers->Signature != MAGIC_PE ||
-      headers->FileHeader.SizeOfOptionalHeader < sizeof(IMAGE_OPTIONAL_HEADER)) {
-    return;
-  }
-
-  // The format of the import directory is described in:
-  // "An In-Depth Look into the Win32 Portable Executable File Format, Part 2"
-  // http://msdn.microsoft.com/en-us/magazine/cc301808.aspx
-
-  IMAGE_DATA_DIRECTORY* importDirectory =
-    &headers->OptionalHeader.DataDirectory[IMAGE_DIRECTORY_ENTRY_IMPORT];
-  RVAPtr<IMAGE_IMPORT_DESCRIPTOR> descriptor(module, importDirectory->VirtualAddress);
-
-  for (; descriptor->OriginalFirstThunk; ++descriptor) {
-    RVAPtr<char> importedModule(module, descriptor->Name);
-    if (!stricmp(importedModule, "kernel32.dll")) {
-      RVAPtr<IMAGE_THUNK_DATA> thunk(module, descriptor->OriginalFirstThunk);
-      for (; thunk->u1.AddressOfData; ++thunk) {
-        RVAPtr<IMAGE_IMPORT_BY_NAME> import(module, thunk->u1.AddressOfData);
-        if (!strcmp((char*)import->Name, "GetLogicalProcessorInformation")) {
-          memcpy(import->Name, "DebugBreak", sizeof("DebugBreak"));
-        }
-      }
-    }
-  }
-}
-
-PIMAGE_NT_HEADERS NTAPI
-patched_RtlImageNtHeader(HMODULE module)
-{
-  PIMAGE_NT_HEADERS headers = stub_RtlImageNtHeader(module);
-
-  if (module == GetModuleHandleW(L"msvcr120.dll")) {
-    PatchModuleImports(module, headers);
-  }
-
-  return headers;
-}
-
-// Non-inline to make the asserts stand out
-MOZ_NEVER_INLINE void
-Init()
-{
-  // If the C Runtime DLL is already loaded, our hooks will be ineffective,
-  // and we will fail to load on XP SP2 when built with Visual Studio 2013.
-  // We assert the absence of these modules on all Windows builds in order to
-  // catch breakage faster.
-  //
-  // If these assertions fail, see the comment at the top of this file for
-  // possible causes. Any changes to the lines below MUST be tested on XP SP2!
-  MOZ_ASSERT(!GetModuleHandleA("mozglue.dll"));
-  MOZ_ASSERT(!GetModuleHandleA("msvcr120.dll"));
-  MOZ_ASSERT(!GetModuleHandleA("msvcr120d.dll"));
-
-#if defined(_M_IX86) && defined(_MSC_VER)
-  if (!mozilla::IsWin2003OrLater()) {
-    // Test for the export because we can't trust the SP version (bug 1137609)
-    HMODULE kernel = GetModuleHandleA("kernel32.dll");
-    if (!kernel || !GetProcAddress(kernel, "GetLogicalProcessorInformation")) {
-      NtdllIntercept.Init("ntdll.dll");
-      NtdllIntercept.AddHook("RtlImageNtHeader",
-                             reinterpret_cast<intptr_t>(patched_RtlImageNtHeader),
-                             reinterpret_cast<void**>(&stub_RtlImageNtHeader));
-    }
-  }
-#endif
-}
-
-} // namespace WindowsCrtPatch
-
-#endif // WindowsCrtPatch_h

--- a/toolkit/xre/nsWindowsWMain.cpp
+++ b/toolkit/xre/nsWindowsWMain.cpp
@@ -18,20 +18,16 @@
 #ifndef XRE_DONT_PROTECT_DLL_LOAD
 #include "nsSetDllDirectory.h"
 #endif
 
 #if defined(__GNUC__)
 #define XRE_DONT_SUPPORT_XPSP2
 #endif
 
-#ifndef XRE_DONT_SUPPORT_XPSP2
-#include "WindowsCrtPatch.h"
-#endif
-
 #ifdef __MINGW32__
 
 /* MingW currently does not implement a wide version of the
    startup routines.  Workaround is to implement something like
    it ourselves.  See bug 411826 */
 
 #include <shellapi.h>
 
@@ -82,20 +78,16 @@ FreeAllocStrings(int argc, char **argv)
     delete [] argv[argc];
   }
 
   delete [] argv;
 }
 
 int wmain(int argc, WCHAR **argv)
 {
-#if !defined(XRE_DONT_SUPPORT_XPSP2)
-  WindowsCrtPatch::Init();
-#endif
-
 #if defined(_MSC_VER) && _MSC_VER < 1900 && defined(_M_X64)
   // Disable CRT use of FMA3 on non-AVX2 CPUs and on Win7RTM due to bug 1160148
   int cpuid0[4] = {0};
   int cpuid7[4] = {0};
   __cpuid(cpuid0, 0); // Get the maximum supported CPUID function
   __cpuid(cpuid7, 7); // AVX2 is function 7, subfunction 0, EBX, bit 5
   if (cpuid0[0] < 7 || !(cpuid7[1] & 0x20) || !mozilla::IsWin7SP1OrLater()) {
     _set_FMA3_enable(0);