new file mode 100644
--- /dev/null
+++ b/extensions/spellcheck/hunspell/glue/common.mozbuild
@@ -0,0 +1,18 @@
+# -*- Mode: python; indent-tabs-mode: nil; tab-width: 40 -*-
+# vim: set filetype=python:
+# 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/.
+
+@template
+def ForceInclude(*headers):
+    if CONFIG['CC_TYPE'] in ('msvc', 'clang-cl'):
+        include_flag = '-FI'
+    else:
+        include_flag = '-include'
+    for header in headers:
+        CXXFLAGS += [include_flag, header]
+
+@template
+def HunspellIncludes():
+    ForceInclude('hunspell_alloc_hooks.h', 'hunspell_fopen_hooks.h')

--- a/extensions/spellcheck/hunspell/glue/hunspell_alloc_hooks.h
+++ b/extensions/spellcheck/hunspell/glue/hunspell_alloc_hooks.h
@@ -34,19 +34,16 @@
 #ifndef alloc_hooks_h__
 #define alloc_hooks_h__
 
 /**
  * This file is force-included in hunspell code.  Its purpose is to add memory
  * reporting to hunspell without modifying its code, in order to ease future
  * upgrades.
  *
- * This file is force-included through mozilla-config.h which is generated
- * during the configure step.
- *
  * Currently, the memory allocated using operator new/new[] is not being
  * tracked, but that's OK, since almost all of the memory used by Hunspell is
  * allocated using C memory allocation functions.
  */
 
 #include "mozilla/mozalloc.h"
 #include "mozHunspellAllocator.h"
 

--- a/extensions/spellcheck/hunspell/glue/hunspell_fopen_hooks.h
+++ b/extensions/spellcheck/hunspell/glue/hunspell_fopen_hooks.h
@@ -4,19 +4,16 @@
 
 #ifndef fopen_hooks_h__
 #define fopen_hooks_h__
 
 /**
  * This file is force-included in hunspell code. Its purpose is to add
  * readahead to fopen() calls in hunspell without modifying its code, in order
  * to ease future upgrades.
- *
- * This file is force-included through mozilla-config.h which is generated
- * during the configure step.
  */
 
 #include "mozilla/FileUtils.h"
 #include <stdio.h>
 #include <string.h>
 
 #if defined(XP_WIN)
 #include "nsNativeCharsetUtils.h"

--- a/extensions/spellcheck/hunspell/glue/moz.build
+++ b/extensions/spellcheck/hunspell/glue/moz.build
@@ -15,21 +15,20 @@ FINAL_LIBRARY = 'xul'
 
 LOCAL_INCLUDES += [
     '../src',
     '/dom/base',
     '/extensions/spellcheck/src',
 ]
 
 include('/ipc/chromium/chromium-config.mozbuild')
+include('common.mozbuild')
+
+HunspellIncludes()
 
 IPDL_SOURCES = [
     'PRemoteSpellcheckEngine.ipdl',
 ]
 
 EXPORTS.mozilla += [
      'RemoteSpellCheckEngineChild.h',
      'RemoteSpellCheckEngineParent.h',
 ]
-
-# This variable is referenced in mozilla-config.h.in.  Make sure to change
-# that file too if you need to change this variable.
-DEFINES['HUNSPELL_STATIC'] = True

--- a/extensions/spellcheck/hunspell/src/moz.build
+++ b/extensions/spellcheck/hunspell/src/moz.build
@@ -10,27 +10,26 @@ UNIFIED_SOURCES += [
     'csutil.cxx',
     'hashmgr.cxx',
     'hunspell.cxx',
     'phonet.cxx',
     'replist.cxx',
     'suggestmgr.cxx',
 ]
 
-# This variable is referenced in mozilla-config.h.in.  Make sure to change
-# that file too if you need to change this variable.
-DEFINES['HUNSPELL_STATIC'] = True
-
 FINAL_LIBRARY = 'xul'
 
 LOCAL_INCLUDES += [
     '../glue',
 ]
 
 # We allow warnings for third-party code that can be updated from upstream.
 AllowCompilerWarnings()
 
 include('/ipc/chromium/chromium-config.mozbuild')
+include('../glue/common.mozbuild')
+
+HunspellIncludes()
 
 if CONFIG['CC_TYPE'] in ('clang', 'clang-cl'):
     CXXFLAGS += [
         '-Wno-implicit-fallthrough',
     ]

--- a/mozilla-config.h.in
+++ b/mozilla-config.h.in
@@ -33,27 +33,16 @@
 #define __STDC_FORMAT_MACROS
 #endif
 
 #if defined(__clang__)
 #pragma clang diagnostic pop
 #endif
 
 /*
- * Force-include hunspell_alloc_hooks.h and hunspell_fopen_hooks.h for hunspell,
- * so that we don't need to modify them directly.
- *
- * HUNSPELL_STATIC is defined in extensions/spellcheck/hunspell/src/moz.build
- */
-#if defined(HUNSPELL_STATIC)
-#include "hunspell_alloc_hooks.h"
-#include "hunspell_fopen_hooks.h"
-#endif
-
-/*
  * Force-include sdkdecls.h for building the chromium sandbox code.
  *
  * CHROMIUM_SANDBOX_BUILD is defined in security/sandbox/moz.build.
  * Note that this include path relies on the LOCAL_INCLUDES in that file.
  */
 #if defined(CHROMIUM_SANDBOX_BUILD) && defined(XP_WIN)
 #include "base/win/sdkdecls.h"