Index: llvm/trunk/tools/xcode-toolchain/CMakeLists.txt
===================================================================
--- llvm/trunk/tools/xcode-toolchain/CMakeLists.txt
+++ llvm/trunk/tools/xcode-toolchain/CMakeLists.txt
@@ -0,0 +1,72 @@
+# OS X 10.11 El Capitan has just been released. One of the new features, System
+# Integrity Protection, prevents modifying the base OS install, even with sudo.
+# This prevents LLVM developers on OS X from being able to easily install new
+# system compilers. The feature can be disabled, but to make it easier for
+# developers to work without disabling SIP, this file can generate an Xcode
+# toolchain. Xcode toolchains are a mostly-undocumented feature that allows
+# multiple copies of low level tools to be installed to different locations, and
+# users can easily switch between them.
+
+# Setting an environment variable TOOLCHAINS to the toolchain's identifier will
+# result in /usr/bin/<tool> or xcrun <tool> to find the tool in the toolchain.
+
+# To make this work with Xcode 7.1 and later you can install the toolchain this
+# file generates anywhere on your system and set EXTERNAL_TOOLCHAINS_DIR to the
+# path specified by $CMAKE_INSTALL_PREFIX/Toolchains
+
+# This file generates a custom install-xcode-toolchain target which constructs
+# and installs a toolchain with the identifier in the pattern:
+# org.llvm.${PACKAGE_VERSION}. This toolchain can then be used to override the
+# system compiler by setting TOOLCHAINS=org.llvm.${PACKAGE_VERSION} in the
+# in the environment.
+
+# Example usage:
+# cmake -G Ninja -DLLVM_CREATE_XCODE_TOOLCHAIN=On
+#   -DCMAKE_INSTALL_PREFIX=$PWD/install
+# ninja install-xcode-toolchain
+# export EXTERNAL_TOOLCHAINS_DIR=$PWD/install/Toolchains
+# export TOOLCHAINS=org.llvm.3.8.0svn
+
+# `xcrun -find clang` should return the installed clang, and `clang --version`
+# should show 3.8.0svn.
+
+if(NOT APPLE)
+  return()
+endif()
+
+option(LLVM_CREATE_XCODE_TOOLCHAIN "Create a target to install LLVM into an Xcode toolchain" Off)
+
+if(NOT LLVM_CREATE_XCODE_TOOLCHAIN)
+  return()
+endif()
+
+execute_process(
+  COMMAND xcrun -find otool
+  OUTPUT_VARIABLE clang_path
+  OUTPUT_STRIP_TRAILING_WHITESPACE
+  ERROR_FILE /dev/null
+)
+string(REGEX MATCH "(.*/Toolchains)/.*" toolchains_match ${clang_path})
+if(NOT toolchains_match)
+  message(FATAL_ERROR "Could not identify toolchain dir")
+endif()
+set(toolchains_dir ${CMAKE_MATCH_1})
+
+set(XcodeDefaultInfo "${toolchains_dir}/XcodeDefault.xctoolchain/ToolchainInfo.plist")
+set(LLVMToolchainDir "${CMAKE_INSTALL_PREFIX}/Toolchains/LLVM${PACKAGE_VERSION}.xctoolchain/")
+
+add_custom_command(OUTPUT ${LLVMToolchainDir}
+                    COMMAND ${CMAKE_COMMAND} -E make_directory ${LLVMToolchainDir})
+
+add_custom_command(OUTPUT ${LLVMToolchainDir}/ToolchainInfo.plist
+                  DEPENDS ${LLVMToolchainDir}
+                  COMMAND ${CMAKE_COMMAND} -E copy "${XcodeDefaultInfo}" "${LLVMToolchainDir}/ToolchainInfo.plist"
+                  COMMAND /usr/libexec/PlistBuddy -c "Set:Identifier org.llvm.${PACKAGE_VERSION}" "${LLVMToolchainDir}/ToolchainInfo.plist")
+
+add_custom_target(install-xcode-toolchain
+                  DEPENDS ${LLVMToolchainDir}/ToolchainInfo.plist
+                  COMMAND "${CMAKE_COMMAND}" --build ${CMAKE_BINARY_DIR} --target all
+                  COMMAND "${CMAKE_COMMAND}"
+                          -DCMAKE_INSTALL_PREFIX=${LLVMToolchainDir}/usr/
+                          -P "${CMAKE_BINARY_DIR}/cmake_install.cmake"
+                  ${cmake_3_2_USES_TERMINAL})