Index: compiler-rt/cmake/Modules/AddCompilerRT.cmake
===================================================================
--- compiler-rt/cmake/Modules/AddCompilerRT.cmake
+++ compiler-rt/cmake/Modules/AddCompilerRT.cmake
@@ -477,56 +477,99 @@
   foreach(flag ${LIBCXX_CFLAGS})
     set(flagstr "${flagstr} ${flag}")
   endforeach()
-  set(LIBCXX_CFLAGS ${flagstr})
+  set(LIBCXX_C_FLAGS ${flagstr})
+  set(LIBCXX_CXX_FLAGS ${flagstr})
 
   if(LIBCXX_USE_TOOLCHAIN)
     set(compiler_args -DCMAKE_C_COMPILER=${COMPILER_RT_TEST_COMPILER}
                       -DCMAKE_CXX_COMPILER=${COMPILER_RT_TEST_CXX_COMPILER})
     if(NOT COMPILER_RT_STANDALONE_BUILD)
-      set(force_deps DEPENDS clang)
+      set(force_deps DEPENDS $<TARGET_FILE:clang>)
+      list(APPEND LIBCXX_DEPS clang)
     endif()
   else()
     set(compiler_args -DCMAKE_C_COMPILER=${CMAKE_C_COMPILER}
                       -DCMAKE_CXX_COMPILER=${CMAKE_CXX_COMPILER})
   endif()
 
+  set(STAMP_DIR ${prefix}-stamps/)
+  set(BINARY_DIR ${prefix}-bins/)
+
+  add_custom_target(${name}-clear
+    COMMAND ${CMAKE_COMMAND} -E remove_directory ${BINARY_DIR}
+    COMMAND ${CMAKE_COMMAND} -E remove_directory ${STAMP_DIR}
+    COMMENT "Clobbering ${name} build and stamp directories"
+    USES_TERMINAL
+    )
+
+  add_custom_command(
+    OUTPUT ${CMAKE_CURRENT_BINARY_DIR}/${name}-clobber-stamp
+    DEPENDS ${LIBCXX_DEPS}
+    COMMAND ${CMAKE_COMMAND} -E touch ${BINARY_DIR}/CMakeCache.txt
+    COMMAND ${CMAKE_COMMAND} -E touch ${STAMP_DIR}/${name}-mkdir
+    COMMAND ${CMAKE_COMMAND} -E touch ${CMAKE_CURRENT_BINARY_DIR}/${name}-clobber-stamp
+    COMMENT "Clobbering bootstrap build and stamp directories"
+    )
+
+  add_custom_target(${name}-clobber
+    DEPENDS ${CMAKE_CURRENT_BINARY_DIR}/${name}-clobber-stamp)
+
   if(CMAKE_SYSROOT)
     set(sysroot_arg -DCMAKE_SYSROOT=${CMAKE_SYSROOT})
   endif()
 
   ExternalProject_Add(${name}
-    DEPENDS ${LIBCXX_DEPS}
+    DEPENDS ${name}-clobber #${LIBCXX_DEPS}
     PREFIX ${prefix}
     SOURCE_DIR ${COMPILER_RT_LIBCXX_PATH}
+    STAMP_DIR ${STAMP_DIR}
+    BINARY_DIR ${BINARY_DIR}
     CMAKE_ARGS -DCMAKE_MAKE_PROGRAM=${CMAKE_MAKE_PROGRAM}
                ${compiler_args}
                ${sysroot_arg}
-               -DCMAKE_C_FLAGS=${LIBCXX_CFLAGS}
-               -DCMAKE_CXX_FLAGS=${LIBCXX_CFLAGS}
+               -DCMAKE_C_FLAGS=${LIBCXX_C_FLAGS}
+               -DCMAKE_CXX_FLAGS=${LIBCXX_CXX_FLAGS}
                -DCMAKE_BUILD_TYPE=Release
-               -DCMAKE_INSTALL_PREFIX=<INSTALL_DIR>
+               -DCMAKE_INSTALL_PREFIX=${CMAKE_INSTALL_PREFIX}
                -DLLVM_PATH=${LLVM_MAIN_SRC_DIR}
-               -DLIBCXX_STANDALONE_BUILD=On
+               -DLIBCXX_STANDALONE_BUILD=ON
                ${LIBCXX_CMAKE_ARGS}
-    STEP_TARGETS configure build install
-    LOG_BUILD 1
-    LOG_CONFIGURE 1
-    LOG_INSTALL 1
+    INSTALL_COMMAND ""
+    STEP_TARGETS configure build
+    BUILD_ALWAYS 1
+    USES_TERMINAL_CONFIGURE 1
+    USES_TERMINAL_BUILD 1
+    USES_TERMINAL_INSTALL 1
     EXCLUDE_FROM_ALL TRUE
     )
 
-  ExternalProject_Add_Step(${name} force-reconfigure
-    DEPENDERS configure
-    ALWAYS 1
-    )
+  if (CMAKE_GENERATOR MATCHES "Make")
+    set(run_clean "$(MAKE)" "-C" "${BINARY_DIR}" "clean")
+  else()
+    set(run_clean ${CMAKE_COMMAND} --build ${BINARY_DIR} --target clean
+                                   --config "$<CONFIGURATION>")
+  endif()
+
+  if(LIBCXX_USE_TOOLCHAIN AND NOT COMPILER_RT_STANDALONE_BUILD)
+  endif()
 
-  ExternalProject_Add_Step(${name} clobber
-    COMMAND ${CMAKE_COMMAND} -E remove_directory <BINARY_DIR>
-    COMMAND ${CMAKE_COMMAND} -E make_directory <BINARY_DIR>
-    COMMENT "Clobberring ${name} build directory..."
-    DEPENDERS configure
+  llvm_ExternalProject_BuildCmd(run_clean clean ${BINARY_DIR})
+  ExternalProject_Add_Step(${name} clean
+    COMMAND ${run_clean}
+    COMMENT "Cleaning ${name}..."
+    DEPENDEES configure
     ${force_deps}
+    WORKING_DIRECTORY ${BINARY_DIR}
+    EXCLUDE_FROM_MAIN 1
+    USES_TERMINAL 1
     )
+  ExternalProject_Add_StepTargets(${name} clean)
+
+  if(LIBCXX_USE_TOOLCHAIN)
+    add_dependencies(${name}-clean ${name}-clobber)
+    set_target_properties(${name}-clean PROPERTIES
+      SOURCES ${CMAKE_CURRENT_BINARY_DIR}/${name}-clobber-stamp)
+  endif()
 endmacro()
 
 function(rt_externalize_debuginfo name)
Index: compiler-rt/lib/fuzzer/CMakeLists.txt
===================================================================
--- compiler-rt/lib/fuzzer/CMakeLists.txt
+++ compiler-rt/lib/fuzzer/CMakeLists.txt
@@ -86,7 +86,7 @@
     set(cxx_${arch}_merge_dir "${CMAKE_CURRENT_BINARY_DIR}/cxx_${arch}_merge.dir")
     file(MAKE_DIRECTORY ${cxx_${arch}_merge_dir})
     add_custom_command(TARGET clang_rt.${name}-${arch} POST_BUILD
-      COMMAND ${CMAKE_LINKER} --whole-archive "$<TARGET_LINKER_FILE:clang_rt.${name}-${arch}>" --no-whole-archive ${dir}/src/libcxx_fuzzer_${arch}-build/lib/libc++.a -r -o ${name}.o
+      COMMAND ${CMAKE_LINKER} --whole-archive "$<TARGET_LINKER_FILE:clang_rt.${name}-${arch}>" --no-whole-archive ${dir}-bins/lib/libc++.a -r -o ${name}.o
       COMMAND ${CMAKE_OBJCOPY} --localize-hidden ${name}.o
       COMMAND ${CMAKE_COMMAND} -E remove "$<TARGET_LINKER_FILE:clang_rt.${name}-${arch}>"
       COMMAND ${CMAKE_AR} qcs "$<TARGET_LINKER_FILE:clang_rt.${name}-${arch}>" ${name}.o
Index: compiler-rt/lib/fuzzer/tests/CMakeLists.txt
===================================================================
--- compiler-rt/lib/fuzzer/tests/CMakeLists.txt
+++ compiler-rt/lib/fuzzer/tests/CMakeLists.txt
@@ -40,7 +40,7 @@
   if("${CMAKE_SYSTEM_NAME}" STREQUAL "Linux" AND COMPILER_RT_LIBCXX_PATH)
     set(LIBFUZZER_TEST_RUNTIME_DEPS libcxx_fuzzer_${arch}-build)
     set(LIBFUZZER_TEST_RUNTIME_CFLAGS -isystem ${COMPILER_RT_LIBCXX_PATH}/include)
-    set(LIBFUZZER_TEST_RUNTIME_LINK_FLAGS ${LIBCXX_${arch}_PREFIX}/src/libcxx_fuzzer_${arch}-build/lib/libc++.a)
+    set(LIBFUZZER_TEST_RUNTIME_LINK_FLAGS ${LIBCXX_${arch}_PREFIX}-bins/lib/libc++.a)
   endif()
 
   set(FuzzerTestObjects)
Index: compiler-rt/lib/msan/tests/CMakeLists.txt
===================================================================
--- compiler-rt/lib/msan/tests/CMakeLists.txt
+++ compiler-rt/lib/msan/tests/CMakeLists.txt
@@ -109,7 +109,7 @@
                    DEPS ${MSAN_INST_LOADABLE_OBJECTS})
 
   set(MSAN_TEST_OBJECTS ${MSAN_INST_TEST_OBJECTS} ${MSAN_INST_GTEST})
-  set(MSAN_TEST_DEPS ${MSAN_TEST_OBJECTS} libcxx_msan_${arch}-install
+  set(MSAN_TEST_DEPS ${MSAN_TEST_OBJECTS} libcxx_msan_${arch}-build
                      ${MSAN_LOADABLE_SO})
   if(NOT COMPILER_RT_STANDALONE_BUILD)
     list(APPEND MSAN_TEST_DEPS msan)
@@ -121,7 +121,7 @@
     LINK_FLAGS ${MSAN_UNITTEST_LINK_FLAGS}
                ${TARGET_LINK_FLAGS}
                "-Wl,-rpath=${CMAKE_CURRENT_BINARY_DIR}"
-               "-Wl,-rpath=${LIBCXX_PREFIX}/lib")
+               "-Wl,-rpath=${LIBCXX_PREFIX}-bins/lib")
 endmacro()
 
 # We should only build MSan unit tests if we can build instrumented libcxx.
@@ -133,7 +133,7 @@
       DEPS ${MSAN_RUNTIME_LIBRARIES}
       CFLAGS ${MSAN_LIBCXX_CFLAGS} ${TARGET_CFLAGS}
       USE_TOOLCHAIN)
-    set(MSAN_LIBCXX_SO ${LIBCXX_PREFIX}/lib/libc++.so)
+    set(MSAN_LIBCXX_SO ${LIBCXX_PREFIX}-bins/lib/libc++.so)
 
     add_msan_tests_for_arch(${arch} "" "")
     add_msan_tests_for_arch(${arch} "-with-call"
Index: compiler-rt/lib/tsan/CMakeLists.txt
===================================================================
--- compiler-rt/lib/tsan/CMakeLists.txt
+++ compiler-rt/lib/tsan/CMakeLists.txt
@@ -214,7 +214,7 @@
       DEPS ${TSAN_RUNTIME_LIBRARIES}
       CFLAGS ${TARGET_CFLAGS} -fsanitize=thread
       USE_TOOLCHAIN)
-    list(APPEND libcxx_tsan_deps libcxx_tsan_${arch}-install)
+    list(APPEND libcxx_tsan_deps libcxx_tsan_${arch}-build)
   endforeach()
 
   add_custom_target(libcxx_tsan DEPENDS ${libcxx_tsan_deps})
Index: compiler-rt/test/lit.common.configured.in
===================================================================
--- compiler-rt/test/lit.common.configured.in
+++ compiler-rt/test/lit.common.configured.in
@@ -21,6 +21,7 @@
 set_default("gold_executable", "@GOLD_EXECUTABLE@")
 set_default("clang", "@COMPILER_RT_RESOLVED_TEST_COMPILER@")
 set_default("compiler_id", "@COMPILER_RT_TEST_COMPILER_ID@")
+set_default("libcxx_path", "@COMPILER_RT_LIBCXX_PATH@")
 set_default("python_executable", "@PYTHON_EXECUTABLE@")
 set_default("compiler_rt_debug", @COMPILER_RT_DEBUG_PYBOOL@)
 set_default("compiler_rt_libdir", "@COMPILER_RT_RESOLVED_LIBRARY_OUTPUT_DIR@")
Index: compiler-rt/test/tsan/lit.cfg
===================================================================
--- compiler-rt/test/tsan/lit.cfg
+++ compiler-rt/test/tsan/lit.cfg
@@ -56,8 +56,8 @@
 if config.has_libcxx and config.host_os != 'Darwin':
   # FIXME: Dehardcode this path somehow.
   libcxx_path = os.path.join(config.compiler_rt_obj_root, "lib",
-                             "tsan", "libcxx_tsan_" + config.target_arch)
-  libcxx_incdir = os.path.join(libcxx_path, "include", "c++", "v1")
+                             "tsan", "libcxx_tsan_%s-bins" % config.target_arch)
+  libcxx_incdir = os.path.join(config.libcxx_path, "include")
   libcxx_libdir = os.path.join(libcxx_path, "lib")
   libcxx_so = os.path.join(libcxx_libdir, "libc++.so")
   clang_tsan_cxxflags += ["-nostdinc++",