--- a/browser/config/tooltool-manifests/macosx64/cross-clang.manifest
+++ b/browser/config/tooltool-manifests/macosx64/cross-clang.manifest
@@ -1,10 +1,10 @@
 [
   {
-    "size": 30823112,
+    "size": 34094283,
     "visibility": "internal",
-    "digest": "0c58e06a3ea8f4641c991a7406fc8733c574f0b4aa773bce0feaa5468d2b8440fa33cea056e16fad2b8a7ef4409ca7228113eb12adc87c3e115129d8a3b3b565",
+    "digest": "8811050fe375bcc566c8b85173d86b8a87aa2148edfed93023735c2de44b66a5a28cbaa1cfd396032447fd803e03f308ed941a200c0e2a1ad9fbe16b5606ee7c",
     "algorithm": "sha512",
     "unpack": true,
-    "filename": "MacOSX10.10.sdk.tar.xz"
+    "filename": "MacOSX10.11.sdk.tar.xz"
   }
 ]

--- a/browser/config/tooltool-manifests/macosx64/cross-releng.manifest
+++ b/browser/config/tooltool-manifests/macosx64/cross-releng.manifest
@@ -1,16 +1,16 @@
 [
   {
-    "size": 35215976,
+    "size": 34094283,
     "visibility": "internal",
-    "digest": "8be736545ddab25ebded188458ce974d5c9a7e29f3c50d2ebfbcb878f6aff853dd2ff5a3528bdefc64396a10101a1b50fd2fe52000140df33643cebe1ea759da",
+    "digest": "8811050fe375bcc566c8b85173d86b8a87aa2148edfed93023735c2de44b66a5a28cbaa1cfd396032447fd803e03f308ed941a200c0e2a1ad9fbe16b5606ee7c",
     "algorithm": "sha512",
     "unpack": true,
-    "filename": "MacOSX10.7.sdk.tar.bz2"
+    "filename": "MacOSX10.11.sdk.tar.xz"
   },
   {
     "version": "rustc 1.19.0 (0ade33941 2017-07-17) repack",
     "size": 155690216,
     "digest": "379f542ea16c775e7bcad36823f0068ca6a1f17c2b25e42ef978d51865298ba4207dc89bbb614805f81a123d12e339209a447afbd12c1122e16f4c7c41e7d92b",
     "algorithm": "sha512",
     "filename": "rustc.tar.xz",
     "unpack": true

--- a/build/macosx/cross-mozconfig.common
+++ b/build/macosx/cross-mozconfig.common
@@ -15,17 +15,17 @@ mk_add_options "export LD_LIBRARY_PATH=$
 
 CROSS_CCTOOLS_PATH=$topsrcdir/cctools
 # This SDK was copied from a local XCode install and uploaded to tooltool.
 # Generate the tarball by running this command with the proper SDK version:
 #   sdk_path=$(xcrun --sdk macosx10.12 --show-sdk-path)
 #   tar -C $(dirname ${sdk_path}) -cHjf /tmp/$(basename ${sdk_path}).tar.bz2 $(basename ${sdk_path})
 # Upload the resulting tarball from /tmp to tooltool, and change the entry in
 # `browser/config/tooltool-manifests/macosx64/cross-releng.manifest`.
-CROSS_SYSROOT=$topsrcdir/MacOSX10.7.sdk
+CROSS_SYSROOT=$topsrcdir/MacOSX10.11.sdk
 CROSS_PRIVATE_FRAMEWORKS=$CROSS_SYSROOT/System/Library/PrivateFrameworks
 FLAGS="-target x86_64-apple-darwin11 -B $CROSS_CCTOOLS_PATH/bin -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 LDFLAGS="-Wl,-syslibroot,$CROSS_SYSROOT -Wl,-dead_strip"