diff -r 000000000000 -r 6474c204b198 xpcom/string/src/moz.build
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/xpcom/string/src/moz.build	Wed Dec 31 06:09:35 2014 +0100
@@ -0,0 +1,31 @@
+# -*- Mode: python; c-basic-offset: 4; 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/.
+
+UNIFIED_SOURCES += [
+    'nsDependentString.cpp',
+    'nsDependentSubstring.cpp',
+    'nsPromiseFlatString.cpp',
+    'nsReadableUtils.cpp',
+    'nsString.cpp',
+    'nsStringComparator.cpp',
+    'nsStringObsolete.cpp',
+    'nsSubstring.cpp',
+    'nsSubstringTuple.cpp',
+]
+
+# Are we targeting x86 or x86-64?  If so, compile the SSE2 functions for
+# nsUTF8Utils.cpp.
+if CONFIG['INTEL_ARCHITECTURE']:
+    SOURCES += ['nsUTF8UtilsSSE2.cpp']
+    SOURCES['nsUTF8UtilsSSE2.cpp'].flags += CONFIG['SSE2_FLAGS']
+
+LOCAL_INCLUDES += [
+    '/mfbt/double-conversion',
+]
+
+MSVC_ENABLE_PGO = True
+
+FINAL_LIBRARY = 'xpcom_core'