--- a/memory/mozalloc/msvc_raise_wrappers.cpp
+++ b/memory/mozalloc/msvc_raise_wrappers.cpp
@@ -4,57 +4,54 @@
 /* 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 <stdio.h>
 
 #include "mozalloc_abort.h"
 
-#define MOZALLOC_DONT_WRAP_RAISE_FUNCTIONS
-#include "mozilla/throw_msvc.h"
-
 __declspec(noreturn) static void abort_from_exception(const char* const which,
                                                       const char* const what);
 static void
 abort_from_exception(const char* const which,  const char* const what)
 {
     fprintf(stderr, "fatal: STL threw %s: ", which);
     mozalloc_abort(what);
 }
 
 namespace std {
 
 // NB: user code is not supposed to touch the std:: namespace.  We're
 // doing this after careful review because we want to define our own
 // exception throwing semantics.  Don't try this at home!
 
-void
+MFBT_API __declspec(noreturn) void
 moz_Xinvalid_argument(const char* what)
 {
     abort_from_exception("invalid_argument", what);
 }
 
-void
+MFBT_API __declspec(noreturn) void
 moz_Xlength_error(const char* what)
 {
     abort_from_exception("length_error", what);
 }
 
-void
+MFBT_API __declspec(noreturn) void
 moz_Xout_of_range(const char* what)
 {
     abort_from_exception("out_of_range", what);
 }
 
-void
+MFBT_API __declspec(noreturn) void
 moz_Xoverflow_error(const char* what)
 {
     abort_from_exception("overflow_error", what);
 }
 
-void
+MFBT_API __declspec(noreturn) void
 moz_Xruntime_error(const char* what)
 {
     abort_from_exception("runtime_error", what);
 }
 
 } // namespace std

--- a/memory/mozalloc/msvc_raise_wrappers.h
+++ b/memory/mozalloc/msvc_raise_wrappers.h
@@ -12,39 +12,25 @@
 #  error "Unable to wrap _RAISE(); CRT _RAISE() already defined"
 #endif
 #ifdef _XUTILITY_
 #  error "Unabled to wrap _X[exception]"(); CRT versions already declared"
 #endif
 
 #include "mozilla/mozalloc_abort.h"
 
-namespace std {
-
-// NB: user code is not supposed to touch the std:: namespace.  We're
-// doing this after careful review because we want to define our own
-// exception throwing semantics.  Don't try this at home!
-
-MFBT_API __declspec(noreturn) void moz_Xinvalid_argument(const char*);
-MFBT_API __declspec(noreturn) void moz_Xlength_error(const char*);
-MFBT_API __declspec(noreturn) void moz_Xout_of_range(const char*);
-MFBT_API __declspec(noreturn) void moz_Xoverflow_error(const char*);
-MFBT_API __declspec(noreturn) void moz_Xruntime_error(const char*);
-
-} // namespace std
-
-#ifndef MOZALLOC_DONT_WRAP_RAISE_FUNCTIONS
-
+// xutility will declare the following functions in the std namespace.
+// We #define them to be named differently so we can ensure the exception
+// throwing semantics of these functions work exactly the way we want, by
+// defining our own versions in msvc_raise_wrappers.cpp.
 #  define _Xinvalid_argument  moz_Xinvalid_argument
 #  define _Xlength_error      moz_Xlength_error
 #  define _Xout_of_range      moz_Xout_of_range
 #  define _Xoverflow_error    moz_Xoverflow_error
 #  define _Xruntime_error     moz_Xruntime_error
 
 #  include <xstddef>
 #  include <xutility>
 
 #  undef _RAISE
 #  define _RAISE(x) mozalloc_abort((x).what())
 
-#endif  // ifndef MOZALLOC_DONT_WRAP_RAISE_FUNCTIONS
-
 #endif  // ifndef mozilla_msvc_raise_wrappers_h