Index: cmake/modules/LLVMExternalProjectUtils.cmake
===================================================================
--- cmake/modules/LLVMExternalProjectUtils.cmake
+++ cmake/modules/LLVMExternalProjectUtils.cmake
@@ -182,7 +182,7 @@
   endif()
 
   if(NOT ARG_NO_INSTALL)
-    install(CODE "execute_process\(COMMAND \${CMAKE_COMMAND} -DCMAKE_INSTALL_PREFIX=\${CMAKE_INSTALL_PREFIX} -P ${BINARY_DIR}/cmake_install.cmake \)"
+    install(CODE "execute_process\(COMMAND \${CMAKE_COMMAND} -P ${BINARY_DIR}/cmake_install.cmake \)"
       COMPONENT ${name})
 
     add_custom_target(install-${name}
Index: runtimes/CMakeLists.txt
===================================================================
--- runtimes/CMakeLists.txt
+++ runtimes/CMakeLists.txt
@@ -61,9 +61,9 @@
   # This variable makes sure that e.g. llvm-lit is found.
   set(LLVM_MAIN_SRC_DIR ${LLVM_BUILD_MAIN_SRC_DIR})
 
-  if(APPLE)
-   set(LLVM_ENABLE_LIBCXX ON CACHE BOOL "")
-  endif()
+  #if(APPLE)
+  set(LLVM_ENABLE_LIBCXX ON CACHE BOOL "")
+  #endif()
 
   set(SAFE_CMAKE_REQUIRED_FLAGS ${CMAKE_REQUIRED_FLAGS})
   set(SAFE_CMAKE_REQUIRED_LIBRARIES ${CMAKE_REQUIRED_LIBRARIES})
@@ -245,39 +245,99 @@
   endforeach()
 
   if(runtimes)
+    # Create a runtimes target that uses this file as its top-level CMake file.
+    # The runtimes target is a configuration of all the runtime libraries
+    # together in a single CMake invocaiton.
+    if(NOT LLVM_RUNTIME_TARGETS)
+      foreach(runtime_name ${runtime_names})
+        list(APPEND extra_targets
+          ${runtime_name}
+          install-${runtime_name}
+          check-${runtime_name})
+      endforeach()
 
-    foreach(runtime_name ${runtime_names})
-      list(APPEND extra_targets
-        ${runtime_name}
-        install-${runtime_name}
-        check-${runtime_name})
-    endforeach()
+      if(LLVM_INCLUDE_TESTS)
+        set(test_targets runtimes-test-depends check-runtimes)
+        foreach(component ${SUB_COMPONENTS})
+          list(APPEND SUB_COMPONENT_CHECK_TARGETS check-${component})
+        endforeach()
+      endif()
 
-    if(LLVM_INCLUDE_TESTS)
-      set(test_targets runtimes-test-depends check-runtimes)
-      foreach(component ${SUB_COMPONENTS})
-        list(APPEND SUB_COMPONENT_CHECK_TARGETS check-${component})
+      llvm_ExternalProject_Add(runtimes
+                               ${CMAKE_CURRENT_SOURCE_DIR}
+                               DEPENDS ${deps}
+                               # Builtins were built separately above
+                               CMAKE_ARGS -DCOMPILER_RT_BUILD_BUILTINS=Off
+                                          -DLLVM_INCLUDE_TESTS=${LLVM_INCLUDE_TESTS}
+                               PASSTHROUGH_PREFIXES ${prefixes}
+                               EXTRA_TARGETS ${extra_targets}
+                                              ${test_targets}
+                                              ${SUB_COMPONENTS}
+                                              ${SUB_COMPONENT_CHECK_TARGETS}
+                                              ${SUB_INSTALL_TARGETS}
+                               USE_TOOLCHAIN
+                               ${EXTRA_ARGS})
+    else()
+      get_cmake_property(variableNames VARIABLES)
+      add_custom_target(runtimes)
+      add_custom_target(install-runtimes)
+      if(LLVM_INCLUDE_TESTS)
+        add_custom_target(check-runtimes)
+        add_custom_target(runtimes-test-depends)
+      endif()
+      foreach(target ${LLVM_RUNTIME_TARGETS})
+        foreach(runtime_name ${runtime_names})
+          list(APPEND ${target}_extra_targets
+            ${runtime_name}-${target}
+            install-${runtime_name}-${target}
+            check-${runtime_name}-${target})
+        endforeach()
+
+        if(LLVM_INCLUDE_TESTS)
+          set(${target}_test_targets runtimes-test-depends-${target} check-runtimes-${target})
+          foreach(component ${SUB_COMPONENTS})
+            list(APPEND SUB_COMPONENT_CHECK_TARGETS check-${component}-${target})
+          endforeach()
+        endif()
+
+        foreach(variableName ${variableNames})
+          if(variableName MATCHES "^RUNTIMES_${target}")
+            string(REPLACE "RUNTIMES_${target}_" "" new_name ${variableName})
+            list(APPEND ${target}_extra_args "-D${new_name}=${${variableName}}")
+          endif()
+        endforeach()
+
+        llvm_ExternalProject_Add(runtimes-${target}
+                                 ${CMAKE_CURRENT_SOURCE_DIR}
+                                 DEPENDS ${deps}
+                                 # Builtins were built separately above
+                                 CMAKE_ARGS -DCOMPILER_RT_BUILD_BUILTINS=Off
+                                            -DLLVM_INCLUDE_TESTS=${LLVM_INCLUDE_TESTS}
+                                            -DCMAKE_C_COMPILER_TARGET=${target}
+                                            -DCMAKE_CXX_COMPILER_TARGET=${target}
+                                            -DCMAKE_ASM_COMPILER_TARGET=${target}
+                                            -DCMAKE_C_COMPILER_WORKS=ON
+                                            -DCMAKE_CXX_COMPILER_WORKS=ON
+                                            -DCMAKE_ASM_COMPILER_WORKS=ON
+                                            ${${target}_extra_args}
+                                 PASSTHROUGH_PREFIXES ${prefixes}
+                                 EXTRA_TARGETS ${${target}_extra_targets}
+                                               ${${target}_test_targets}
+                                               ${SUB_COMPONENTS}
+                                               ${SUB_COMPONENT_CHECK_TARGETS}
+                                               ${SUB_INSTALL_TARGETS}
+                                 USE_TOOLCHAIN
+                                 ${EXTRA_ARGS})
+
+        add_dependencies(runtimes runtimes-${target})
+        add_dependencies(install-runtimes install-runtimes-${target})
+        if(LLVM_INCLUDE_TESTS)
+          add_dependencies(check-runtimes check-runtimes-${target})
+          add_dependencies(runtimes-test-depends runtimes-test-depends-${target})
+        endif()
       endforeach()
     endif()
 
-    # Create a runtimes target that uses this file as its top-level CMake file.
-    # The runtimes target is a configuration of all the runtime libraries
-    # together in a single CMake invocaiton.
-    llvm_ExternalProject_Add(runtimes
-                             ${CMAKE_CURRENT_SOURCE_DIR}
-                             DEPENDS ${deps}
-                             # Builtins were built separately above
-                             CMAKE_ARGS -DCOMPILER_RT_BUILD_BUILTINS=Off
-                                        -DLLVM_INCLUDE_TESTS=${LLVM_INCLUDE_TESTS}
-                             PASSTHROUGH_PREFIXES ${prefixes}
-                             EXTRA_TARGETS ${extra_targets}
-                                            ${test_targets}
-                                            ${SUB_COMPONENTS}
-                                            ${SUB_COMPONENT_CHECK_TARGETS}
-                                            ${SUB_INSTALL_TARGETS}
-                             USE_TOOLCHAIN
-                             ${EXTRA_ARGS})
-    
     # TODO: This is a hack needed because the libcxx headers are copied into the
     # build directory during configuration. Without that step the clang in the
     # build directory cannot find the C++ headers in certain configurations.