diff --git a/build/build-clang/build-clang.py b/build/build-clang/build-clang.py
index 8384ef5b1330..44cb9f733a6c 100755
--- a/build/build-clang/build-clang.py
+++ b/build/build-clang/build-clang.py
@@ -235,6 +235,8 @@ def build_one_stage(cc, cxx, asm, ld, ar, ranlib, libtool,
                 "-DCMAKE_SYSTEM_NAME=Darwin",
                 "-DCMAKE_SYSTEM_VERSION=10.10",
                 "-DLLVM_ENABLE_THREADS=OFF",
+                # Xray requires a OSX 10.12 SDK (https://bugs.llvm.org/show_bug.cgi?id=38959)
+                "-DCOMPILER_RT_BUILD_XRAY=OFF",
                 "-DLIBCXXABI_LIBCXX_INCLUDES=%s" % libcxx_include_dir,
                 "-DCMAKE_OSX_SYSROOT=%s" % slashify_path(os.getenv("CROSS_SYSROOT")),
                 "-DCMAKE_FIND_ROOT_PATH=%s" % slashify_path(os.getenv("CROSS_CCTOOLS_PATH")), # noqa
diff --git a/build/build-clang/clang-6-macosx64.json b/build/build-clang/clang-7-macosx64.json
similarity index 82%
rename from build/build-clang/clang-6-macosx64.json
rename to build/build-clang/clang-7-macosx64.json
index ddbed23dd8c3..1470a1d2a8e4 100644
--- a/build/build-clang/clang-6-macosx64.json
+++ b/build/build-clang/clang-7-macosx64.json
@@ -1,16 +1,16 @@
 {
-    "llvm_revision": "335538",
+    "llvm_revision": "342383",
     "stages": "1",
     "build_libcxx": true,
     "build_type": "Release",
     "assertions": false,
     "osx_cross_compile": true,
-    "llvm_repo": "https://llvm.org/svn/llvm-project/llvm/tags/RELEASE_601/final",
-    "clang_repo": "https://llvm.org/svn/llvm-project/cfe/tags/RELEASE_601/final",
-    "lld_repo": "https://llvm.org/svn/llvm-project/lld/tags/RELEASE_601/final",
-    "compiler_repo": "https://llvm.org/svn/llvm-project/compiler-rt/tags/RELEASE_601/final",
-    "libcxx_repo": "https://llvm.org/svn/llvm-project/libcxx/tags/RELEASE_601/final",
-    "libcxxabi_repo": "https://llvm.org/svn/llvm-project/libcxxabi/tags/RELEASE_601/final",
+    "llvm_repo": "https://llvm.org/svn/llvm-project/llvm/tags/RELEASE_700/final",
+    "clang_repo": "https://llvm.org/svn/llvm-project/cfe/tags/RELEASE_700/final",
+    "lld_repo": "https://llvm.org/svn/llvm-project/lld/tags/RELEASE_700/final",
+    "compiler_repo": "https://llvm.org/svn/llvm-project/compiler-rt/tags/RELEASE_700/final",
+    "libcxx_repo": "https://llvm.org/svn/llvm-project/libcxx/tags/RELEASE_700/final",
+    "libcxxabi_repo": "https://llvm.org/svn/llvm-project/libcxxabi/tags/RELEASE_700/final",
     "python_path": "/usr/bin/python2.7",
     "gcc_dir": "/builds/worker/workspace/build/src/gcc",
     "cc": "/builds/worker/workspace/build/src/clang/bin/clang",
@@ -23,9 +23,6 @@
     "patches": [
       "static-llvm-symbolizer.patch",
       "compiler-rt-cross-compile.patch",
-      "compiler-rt-no-codesign.patch",
-      "r322401.patch",
-      "r325356.patch",
-      "r339636.patch"
+      "compiler-rt-no-codesign.patch"
     ]
 }
diff --git a/build/build-clang/compiler-rt-no-codesign.patch b/build/build-clang/compiler-rt-no-codesign.patch
index f1a769cbfc4c..92a584de917d 100644
--- a/build/build-clang/compiler-rt-no-codesign.patch
+++ b/build/build-clang/compiler-rt-no-codesign.patch
@@ -2,9 +2,9 @@ Disable codesign for macosx cross-compile toolchain. Codesign only works on OSX.
 
 Index: cmake/Modules/AddCompilerRT.cmake
 ===================================================================
---- a/compiler-rt/cmake/Modules/AddCompilerRT.cmake	(revision 312553)
+--- a/compiler-rt/cmake/Modules/AddCompilerRT.cmake	(revision 342374)
 +++ b/compiler-rt/cmake/Modules/AddCompilerRT.cmake	(working copy)
-@@ -224,14 +224,6 @@
+@@ -290,14 +290,6 @@
          set_target_properties(${libname} PROPERTIES IMPORT_PREFIX "")
          set_target_properties(${libname} PROPERTIES IMPORT_SUFFIX ".lib")
        endif()
@@ -18,4 +18,4 @@ Index: cmake/Modules/AddCompilerRT.cmake
 -      endif()
      endif()
      install(TARGETS ${libname}
-       ARCHIVE DESTINATION ${COMPILER_RT_LIBRARY_INSTALL_DIR}
+       ARCHIVE DESTINATION ${install_dir_${libname}}
diff --git a/taskcluster/ci/toolchain/linux.yml b/taskcluster/ci/toolchain/linux.yml
index b326f0588ba2..d904d7e578b2 100755
--- a/taskcluster/ci/toolchain/linux.yml
+++ b/taskcluster/ci/toolchain/linux.yml
@@ -44,7 +44,6 @@ linux64-clang-6:
             - 'build/build-clang/build-clang.py'
             - 'build/build-clang/clang-6-linux64.json'
             - 'taskcluster/scripts/misc/tooltool-download.sh'
-        toolchain-alias: linux64-clang
         toolchain-artifact: public/build/clang.tar.xz
     toolchains:
         - linux64-gcc-4.9
@@ -66,6 +65,7 @@ linux64-clang-7:
             - 'build/build-clang/build-clang.py'
             - 'build/build-clang/clang-7-linux64.json'
             - 'taskcluster/scripts/misc/tooltool-download.sh'
+        toolchain-alias: linux64-clang
         toolchain-artifact: public/build/clang.tar.xz
     toolchains:
         - linux64-gcc-4.9
@@ -118,12 +118,12 @@ linux64-clang-trunk-mingw-x64:
     toolchains:
         - linux64-gcc-4.9
 
-linux64-clang-6-macosx-cross:
-    description: "Clang 6 toolchain build with MacOS Compiler RT libs"
+linux64-clang-7-macosx-cross:
+    description: "Clang 7 toolchain build with MacOS Compiler RT libs"
     treeherder:
         kind: build
         platform: toolchains/opt
-        symbol: TL(clang6-macosx-cross)
+        symbol: TL(clang7-macosx-cross)
         tier: 1
     worker-type: aws-provisioner-v1/gecko-{level}-b-linux
     worker:
@@ -132,17 +132,17 @@ linux64-clang-6-macosx-cross:
             TOOLTOOL_MANIFEST: "browser/config/tooltool-manifests/macosx64/cross-clang.manifest"
     run:
         using: toolchain-script
-        script: build-clang-6-linux-macosx-cross.sh
+        script: build-clang-7-linux-macosx-cross.sh
         resources:
             - 'build/build-clang/build-clang.py'
-            - 'build/build-clang/clang-6-macosx64.json'
+            - 'build/build-clang/clang-7-macosx64.json'
             - 'taskcluster/scripts/misc/tooltool-download.sh'
         toolchain-alias: linux64-clang-macosx-cross
         toolchain-artifact: public/build/clang.tar.xz
         tooltool-downloads: internal
     toolchains:
         - linux64-cctools-port
-        - linux64-clang-6
+        - linux64-clang-7
         - linux64-gcc-4.9
 
 linux64-clang-tidy:
@@ -354,7 +354,7 @@ linux64-cctools-port:
             - 'taskcluster/scripts/misc/tooltool-download.sh'
         toolchain-artifact: public/build/cctools.tar.xz
     toolchains:
-        - linux64-clang-6
+        - linux64-clang-7
 
 linux64-hfsplus:
     description: "hfsplus toolchain build"
diff --git a/taskcluster/ci/toolchain/macosx.yml b/taskcluster/ci/toolchain/macosx.yml
index db28a8a8cff0..80c5f37a6a4f 100644
--- a/taskcluster/ci/toolchain/macosx.yml
+++ b/taskcluster/ci/toolchain/macosx.yml
@@ -27,12 +27,12 @@ macosx64-clang:
         tooltool-downloads: internal
         resources:
             - 'build/build-clang/build-clang.py'
-            - 'build/build-clang/clang-6-macosx64.json'
+            - 'build/build-clang/clang-7-macosx64.json'
             - 'taskcluster/scripts/misc/tooltool-download.sh'
         toolchain-artifact: public/build/clang.tar.xz
     toolchains:
         - linux64-cctools-port
-        - linux64-clang-6
+        - linux64-clang-7
         - linux64-gcc-4.9
         - linux64-node
 
@@ -63,7 +63,7 @@ macosx64-clang-tidy:
         toolchain-artifact: public/build/clang-tidy.tar.xz
     toolchains:
         - linux64-cctools-port
-        - linux64-clang-6
+        - linux64-clang-7
         - linux64-gcc-4.9
         - linux64-node
 
@@ -88,7 +88,7 @@ macosx64-cctools-port:
         toolchain-artifact: public/build/cctools.tar.bz2
     toolchains:
         - linux64-cctools-port
-        - linux64-clang-6
+        - linux64-clang-7
         - linux64-node
 
 macosx64-gn:
@@ -113,7 +113,7 @@ macosx64-gn:
         toolchain-artifact: public/build/gn.tar.xz
     toolchains:
         - linux64-cctools-port
-        - linux64-clang-6
+        - linux64-clang-7
         - linux64-node
 
 macosx64-node:
diff --git a/taskcluster/scripts/misc/build-cctools-port.sh b/taskcluster/scripts/misc/build-cctools-port.sh
index 1392764cba47..d26f0cdbdd77 100755
--- a/taskcluster/scripts/misc/build-cctools-port.sh
+++ b/taskcluster/scripts/misc/build-cctools-port.sh
@@ -48,7 +48,7 @@ export LDFLAGS="-lpthread -Wl,-rpath-link,$CLANG_DIR/lib"
 make -j `nproc --all` install
 strip $CROSSTOOLS_BUILD_DIR/bin/*
 # cctools-port doesn't include dsymutil but clang will need to find it.
-cp $CLANG_DIR/bin/llvm-dsymutil $CROSSTOOLS_BUILD_DIR/bin/x86_64-apple-darwin11-dsymutil
+cp $CLANG_DIR/bin/dsymutil $CROSSTOOLS_BUILD_DIR/bin/x86_64-apple-darwin11-dsymutil
 
 # Put a tarball in the artifacts dir
 mkdir -p $UPLOAD_DIR
diff --git a/taskcluster/scripts/misc/build-clang-6-linux-macosx-cross.sh b/taskcluster/scripts/misc/build-clang-7-linux-macosx-cross.sh
similarity index 95%
rename from taskcluster/scripts/misc/build-clang-6-linux-macosx-cross.sh
rename to taskcluster/scripts/misc/build-clang-7-linux-macosx-cross.sh
index 2f5d3653e771..e009deb7da2c 100755
--- a/taskcluster/scripts/misc/build-clang-6-linux-macosx-cross.sh
+++ b/taskcluster/scripts/misc/build-clang-7-linux-macosx-cross.sh
@@ -25,7 +25,7 @@ set +x
 
 cd build/build-clang
 # |mach python| sets up a virtualenv for us!
-../../mach python ./build-clang.py -c clang-6-macosx64.json --skip-tar
+../../mach python ./build-clang.py -c clang-7-macosx64.json --skip-tar
 
 # We now have a native macosx64 toolchain.
 # What we want is a native linux64 toolchain which can target macosx64 and use the sanitizer dylibs.
diff --git a/taskcluster/scripts/misc/build-clang-macosx.sh b/taskcluster/scripts/misc/build-clang-macosx.sh
index 1e7d8c2bc3fc..b26d608841c6 100755
--- a/taskcluster/scripts/misc/build-clang-macosx.sh
+++ b/taskcluster/scripts/misc/build-clang-macosx.sh
@@ -24,7 +24,7 @@ set +x
 
 cd build/build-clang
 # |mach python| sets up a virtualenv for us!
-../../mach python ./build-clang.py -c clang-6-macosx64.json
+../../mach python ./build-clang.py -c clang-7-macosx64.json
 
 set -x