--- a/configure.in
+++ b/configure.in
@@ -749,19 +749,16 @@ if test -n "$_WIN32_MSVC"; then
     SKIP_COMPILER_CHECKS=1
     SKIP_LIBRARY_CHECKS=1
 
     # Since we're skipping compiler and library checks, hard-code
     # some facts here.
     AC_DEFINE(HAVE_IO_H)
     AC_DEFINE(HAVE_SETBUF)
     AC_DEFINE(HAVE_ISATTY)
-    if test $_MSC_VER -ge 1600; then
-        AC_DEFINE(HAVE_NULLPTR)
-    fi
 fi
 
 fi # COMPILE_ENVIRONMENT
 
 AC_SUBST(MIDL_FLAGS)
 AC_SUBST(_MSC_VER)
 
 AC_SUBST(GNU_AS)
@@ -2799,31 +2796,16 @@ dnl Note that we assume that mac & win32
         else
             WCHAR_CFLAGS="-fshort-wchar"
         fi
     else
         CXXFLAGS=$_SAVE_CXXFLAGS
     fi
 fi
 
-dnl Check for nullptr (bug 626472)
-AC_LANG_CPLUSPLUS
-AC_MSG_CHECKING(for nullptr)
-AC_CACHE_VAL(ac_cv_nullptr,
- [AC_TRY_COMPILE([],
-                 [int* foo = nullptr;],
-                 [ac_cv_nullptr=true],
-                 [ac_cv_nullptr=false])])
-if test "$ac_cv_nullptr" = true ; then
-  AC_DEFINE(HAVE_NULLPTR)
-  AC_MSG_RESULT(yes)
-else
-  AC_MSG_RESULT(no)
-fi
-
 AC_LANG_C
 
 dnl Check for .hidden assembler directive and visibility attribute.
 dnl Borrowed from glibc configure.in
 dnl ===============================================================
 if test "$GNU_CC"; then
   AC_CACHE_CHECK(for visibility(hidden) attribute,
                  ac_cv_visibility_hidden,

--- a/gfx/2d/Types.h
+++ b/gfx/2d/Types.h
@@ -1,34 +1,18 @@
 /* -*- Mode: C++; tab-width: 20; 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/. */
 
 #ifndef MOZILLA_GFX_TYPES_H_
 #define MOZILLA_GFX_TYPES_H_
 
-/**
- * Use C++11 nullptr if available; otherwise use a C++ typesafe template; and
- * for C, fall back to longs.  See bugs 547964 and 626472.
- * Copy and paste job from nscore.h, see bug 781943
- */
-#if defined(MOZ_GFX) && !defined(HAVE_NULLPTR)
-#ifndef __cplusplus
-# define nullptr ((void*)0)
-#elif defined(__GNUC__)
-# define nullptr __null
-#elif defined(_WIN64)
-# define nullptr 0LL
-#else
-# define nullptr 0L
-#endif
-#endif /* defined(MOZ_GFX) && !defined(HAVE_NULLPTR) */
-
 #include "mozilla/StandardInteger.h"
+#include "mozilla/NullPtr.h"
 
 #include <stddef.h>
 
 namespace mozilla {
 namespace gfx {
 
 typedef float Float;
 

new file mode 100644
--- /dev/null
+++ b/mfbt/NullPtr.h
@@ -0,0 +1,46 @@
+/* -*- Mode: C++; tab-width: 2; 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/. */
+
+/*
+ * Implements a workaround for compilers which do not support the C++11 nullptr
+ * constant.
+ */
+
+#ifndef mozilla_NullPtr_h_
+#define mozilla_NullPtr_h_
+
+#if defined(__clang__)
+#  ifndef __has_extension
+#    define __has_extension __has_feature
+#  endif
+#  if __has_extension(cxx_nullptr)
+#    define MOZ_HAVE_CXX11_NULLPTR
+#  endif
+#elif defined(__GNUC__)
+#  if defined(_GXX_EXPERIMENTAL_CXX0X__) || __cplusplus >= 201103L
+#    if (__GNUC__ * 1000 + __GNU_MINOR__) >= 4006
+#      define MOZ_HAVE_CXX11_NULLPTR
+#    endif
+#  endif
+#elif _MSC_VER >= 1600
+# define MOZ_HAVE_CXX11_NULLPTR
+#endif
+
+/**
+ * Use C++11 nullptr if available; otherwise use __null for gcc, or a 0 literal
+ * with the correct size to match the size of a pointer on a given platform.
+ */
+
+#ifndef MOZ_HAVE_CXX11_NULLPTR
+#  if defined(__GNUC__)
+#    define nullptr __null
+#  elif defined(_WIN64)
+#    define nullptr 0LL
+#  else
+#    define nullptr 0L
+#  endif
+#endif
+
+#endif  /* mozilla_NullPtr_h_ */

--- a/mfbt/exported_headers.mk
+++ b/mfbt/exported_headers.mk
@@ -16,16 +16,17 @@ EXPORTS_mozilla += \
   Constants.h \
   FloatingPoint.h \
   GuardObjects.h \
   HashFunctions.h \
   Likely.h \
   LinkedList.h \
   MathAlgorithms.h \
   MSStdInt.h \
+  NullPtr.h \
   RangedPtr.h \
   RefPtr.h \
   Scoped.h \
   StandardInteger.h \
   SHA1.h \
   ThreadLocal.h \
   TypeTraits.h \
   Types.h \

--- a/xpcom/base/nscore.h
+++ b/xpcom/base/nscore.h
@@ -21,16 +21,18 @@
 #endif
 
 /**
  * Incorporate the integer data types which XPCOM uses.
  */
 #include "mozilla/StandardInteger.h"
 #include "stddef.h"
 
+#include "mozilla/NullPtr.h"
+
 /*
  * This is for functions that are like malloc_usable_size.  Such functions are
  * used for measuring the size of data structures.
  */
 typedef size_t(*nsMallocSizeOfFun)(const void *p);
 
 /* Core XPCOM declarations. */
 
@@ -319,32 +321,16 @@ typedef uint32_t nsresult;
  * IUnknown.
  */
 #ifdef XP_WIN
 typedef unsigned long nsrefcnt;
 #else
 typedef uint32_t nsrefcnt;
 #endif
 
-/**
- * Use C++11 nullptr if available; otherwise use a C++ typesafe template; and
- * for C, fall back to longs.  See bugs 547964 and 626472.
- */
-#ifndef HAVE_NULLPTR
-#ifndef __cplusplus
-# define nullptr ((void*)0)
-#elif defined(__GNUC__)
-# define nullptr __null
-#elif defined(_WIN64)
-# define nullptr 0LL
-#else
-# define nullptr 0L
-#endif
-#endif /* defined(HAVE_NULLPTR) */
-
 #include "nsError.h"
 
 /* ------------------------------------------------------------------------ */
 /* Casting macros for hiding C++ features from older compilers */
 
   /* under VC++ (Windows), we don't have autoconf yet */
 #if defined(_MSC_VER)
   #define HAVE_CPP_2BYTE_WCHAR_T