Index: CMakeLists.txt
===================================================================
--- CMakeLists.txt
+++ CMakeLists.txt
@@ -96,6 +96,7 @@
 
   option(LLVM_FORCE_USE_OLD_HOST_TOOLCHAIN
     "Set to ON to force using an old, unsupported host toolchain." OFF)
+  option(CLANG_ENABLE_BOOTSTRAP "Generate the clang bootstrap target" OFF)
 
   include(AddLLVM)
   include(TableGen)
@@ -551,3 +552,45 @@
     ${CLANG_BINARY_DIR}/share/clang/cmake/ClangConfig.cmake
     COPYONLY)
 endif ()
+
+if (CLANG_ENABLE_BOOTSTRAP)
+  include(ExternalProject)
+
+  if(CMAKE_VERSION VERSION_LESS 3.3.20150708)
+    set(cmake_3_4_USES_TERMINAL_OPTIONS)
+  else()
+    set(cmake_3_4_USES_TERMINAL_OPTIONS
+      USES_TERMINAL_CONFIGURE 1
+      USES_TERMINAL_BUILD 1
+      USES_TERMINAL_INSTALL 1)
+  endif()
+  
+
+  ExternalProject_Add(bootstrap
+    DEPENDS clang
+    PREFIX bootstrap
+    SOURCE_DIR ${CMAKE_SOURCE_DIR}
+    CMAKE_ARGS
+                # We shouldn't need to set this here, but INSTALL_DIR doesn't
+                # seem to work, so instead I'm passing this through
+                -DCMAKE_INSTALL_PREFIX=${CMAKE_INSTALL_PREFIX}
+                ${CLANG_BOOTSTRAP_CMAKE_ARGS}
+                -DCMAKE_CXX_COMPILER=${CMAKE_BINARY_DIR}/bin/clang++
+                -DCMAKE_C_COMPILER=${CMAKE_BINARY_DIR}/bin/clang
+    STEP_TARGETS configure build install
+    ${cmake_3_4_USES_TERMINAL_OPTIONS}
+    )
+  
+  ExternalProject_Add_Step(bootstrap force-reconfigure
+    DEPENDERS configure
+    ALWAYS 1
+    )
+
+  ExternalProject_Add_Step(bootstrap clobber
+    COMMAND ${CMAKE_COMMAND} -E remove_directory <BINARY_DIR>
+    COMMAND ${CMAKE_COMMAND} -E make_directory <BINARY_DIR>
+    COMMENT "Clobberring bootstrap build directory..."
+    DEPENDERS configure
+    DEPENDS clang
+  )
+endif()