--- a/build/macosx/local-mozconfig.common
+++ b/build/macosx/local-mozconfig.common
@@ -6,34 +6,46 @@ if [ "x$IS_NIGHTLY" = "xyes" ]; then
   # Some nightlies (eg: Mulet) don't want these set.
   MOZ_AUTOMATION_UPLOAD_SYMBOLS=${MOZ_AUTOMATION_UPLOAD_SYMBOLS-1}
   MOZ_AUTOMATION_UPDATE_PACKAGING=${MOZ_AUTOMATION_UPDATE_PACKAGING-1}
 fi
 . "$topsrcdir/build/mozconfig.common"
 
 if [ -d "$topsrcdir/clang" ]; then
     # mozilla-central based build
-    export CC=$topsrcdir/clang/bin/clang
-    export CXX=$topsrcdir/clang/bin/clang++
+    export CROSS_SYSROOT=$topsrcdir/MacOSX10.11.sdk
+    CROSS_PRIVATE_FRAMEWORKS=$CROSS_SYSROOT/System/Library/PrivateFrameworks
+    FLAGS="-isysroot $CROSS_SYSROOT"
+    export CC="$topsrcdir/clang/bin/clang $FLAGS"
+    export CXX="$topsrcdir/clang/bin/clang++ $FLAGS"
+    export CPP="$topsrcdir/clang/bin/clang $FLAGS -E"
     export LLVMCONFIG=$topsrcdir/clang/bin/llvm-config
     export DSYMUTIL=$topsrcdir/clang/bin/llvm-dsymutil
     # Use an updated linker.
-    ldflags="-B$topsrcdir/cctools/bin"
+    ldflags="-B$topsrcdir/cctools/bin -Wl,-syslibroot,$CROSS_SYSROOT "
+    export BINDGEN_CFLAGS="$FLAGS"
     export AR=$topsrcdir/cctools/bin/ar
     export RANLIB=$topsrcdir/cctools/bin/ranlib
+    ac_add_options --with-macos-private-frameworks=$CROSS_PRIVATE_FRAMEWORKS
 elif [ -d "$topsrcdir/../clang" ]; then
     # comm-central based build
-    export CC=$topsrcdir/../clang/bin/clang
-    export CXX=$topsrcdir/../clang/bin/clang++
+    export CROSS_SYSROOT=$topsrcdir/../MacOSX10.11.sdk
+    CROSS_PRIVATE_FRAMEWORKS=$CROSS_SYSROOT/System/Library/PrivateFrameworks
+    FLAGS="-isysroot $CROSS_SYSROOT"
+    export CC="$topsrcdir/../clang/bin/clang $FLAGS"
+    export CXX="$topsrcdir/../clang/bin/clang++ $FLAGS"
+    export CPP="$topsrcdir/../clang/bin/clang $FLAGS -E"
     export LLVMCONFIG=$topsrcdir/../clang/bin/llvm-config
     export DSYMUTIL=$topsrcdir/../clang/bin/llvm-dsymutil
     # Use an updated linker.
-    ldflags="-B$topsrcdir/../cctools/bin"
+    ldflags="-B$topsrcdir/../cctools/bin -Wl,-syslibroot,$CROSS_SYSROOT "
+    export BINDGEN_CFLAGS="$FLAGS"
     export AR=$topsrcdir/../cctools/bin/ar
     export RANLIB=$topsrcdir/../cctools/bin/ranlib
+    ac_add_options --with-macos-private-frameworks=$CROSS_PRIVATE_FRAMEWORKS
 fi
 
 # Ensure the updated linker doesn't generate things our older build tools
 # don't understand.
 ldflags="$ldflags -Wl,-no_data_in_code_info"
 export LDFLAGS="$ldflags"
 
 # If not set use the system default clang

--- a/mail/config/mozconfigs/macosx64/nightly
+++ b/mail/config/mozconfigs/macosx64/nightly
@@ -1,19 +1,20 @@
 # Big Hack that unsets CC / CXX so that mozconfig.common doesn't get
 # mixed up with host/target CPUs when trying to work out how to do the
 # universal build. When we redo the build system (bug 648979) this will
 # go away.
 if test -e "$topsrcdir/mail/config/version.txt"; then
   unset CC
   unset CXX
+  . $topsrcdir/../build/macosx/mozconfig.common
+else
+  . $topsrcdir/build/macosx/mozconfig.common
 fi
 
-. $topsrcdir/build/macosx/mozconfig.common
-
 ac_add_options --enable-application=mail
 ac_add_options --enable-update-channel=${MOZ_UPDATE_CHANNEL}
 ac_add_options --disable-install-strip
 ac_add_options --enable-profiling
 ac_add_options --enable-calendar
 
 # For NSS symbols
 export MOZ_DEBUG_SYMBOLS=1

--- a/mail/config/tooltool-manifests/macosx64/clang.manifest
+++ b/mail/config/tooltool-manifests/macosx64/clang.manifest
@@ -26,10 +26,18 @@
   },
   {
     "version": "cctools port from commit hash 8e9c3f2506b51",
     "size": 2233376,
     "digest": "d632ef587f0253f016aa5323999a3d9576284c04e66b5243a5780af9a55f474ac91ad8dee5bd86a6ee4e2593e2b345e2fd0aa4e8838b3686f84c5c5ac5c9c418",
     "algorithm": "sha512",
     "filename": "cctools.tar.bz2",
     "unpack": true
+  },
+  {
+    "size":  30823112,
+    "visibility": "internal",
+    "digest": "0c58e06a3ea8f4641c991a7406fc8733c574f0b4aa773bce0feaa5468d2b8440fa33cea056e16fad2b8a7ef4409ca7228113eb12adc87c3e115129d8a3b3b565",
+    "algorithm": "sha512",
+    "unpack": true,
+    "filename": "MacOSX10.10.sdk.tar.xz"
   }
 ]