diff -r 000000000000 -r 6474c204b198 build/macosx/universal/mozconfig.common
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/build/macosx/universal/mozconfig.common	Wed Dec 31 06:09:35 2014 +0100
@@ -0,0 +1,53 @@
+# 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/.
+
+mk_add_options MOZ_UNIFY_BDATE=1
+
+mk_add_options MOZ_POSTFLIGHT_ALL+=build/macosx/universal/flight.mk
+
+DARWIN_VERSION=`uname -r`
+ac_add_app_options i386 --target=i386-apple-darwin$DARWIN_VERSION
+ac_add_app_options x86_64 --target=x86_64-apple-darwin$DARWIN_VERSION
+ac_add_app_options i386 --with-unify-dist=../x86_64/dist
+ac_add_app_options x86_64 --with-unify-dist=../i386/dist
+
+ac_add_options --with-macos-sdk=/Developer/SDKs/MacOSX10.6.sdk
+
+. $topsrcdir/build/macosx/mozconfig.common
+
+# $MOZ_BUILD_APP is only defined when sourced by configure.  That's not a
+# problem, because the variables it affects only need to be set for
+# configure.
+if test -n "$MOZ_BUILD_APP" ; then
+if test "$MOZ_BUILD_APP" = "i386" -o "$MOZ_BUILD_APP" = "x86_64"; then
+  TARGET_CPU=$MOZ_BUILD_APP
+
+  # $HOST_CXX is presently unused.  $HOST_CC will only be used during a cross
+  # compile.
+  HOST_CC=$CC
+  HOST_CXX=$CXX
+
+  NATIVE_CPU=`$topsrcdir/build/autoconf/config.guess | cut -f1 -d-`
+
+  # It's not strictly necessary to specify -arch during native builds, but it
+  # makes the merged about:buildconfig easier to follow, and it reduces
+  # conditionalized differences between builds.
+  CC="$CC -arch $TARGET_CPU"
+  CXX="$CXX -arch $TARGET_CPU"
+
+  # These must be set for cross builds, and don't hurt straight builds.
+  RANLIB=ranlib
+  AR=ar
+  AS=$CC
+  LD=ld
+  STRIP="strip"
+
+  # Each per-CPU build should be entirely oblivious to the fact that a
+  # universal binary will be produced.  The exception is packager.mk, which
+  # needs to know to look for universal bits when building the .dmg.
+  UNIVERSAL_BINARY=1
+
+  export CC CXX HOST_CC HOST_CXX RANLIB AR AS LD STRIP
+fi
+fi