Index: compiler-rt/trunk/cmake/Modules/AddCompilerRT.cmake
===================================================================
--- compiler-rt/trunk/cmake/Modules/AddCompilerRT.cmake
+++ compiler-rt/trunk/cmake/Modules/AddCompilerRT.cmake
@@ -474,11 +474,6 @@
   endif()
 
   cmake_parse_arguments(LIBCXX "USE_TOOLCHAIN" "" "DEPS;CFLAGS;CMAKE_ARGS" ${ARGN})
-  foreach(flag ${LIBCXX_CFLAGS})
-    set(flagstr "${flagstr} ${flag}")
-  endforeach()
-  set(LIBCXX_C_FLAGS ${flagstr})
-  set(LIBCXX_CXX_FLAGS ${flagstr})
 
   if(LIBCXX_USE_TOOLCHAIN)
     set(compiler_args -DCMAKE_C_COMPILER=${COMPILER_RT_TEST_COMPILER}
@@ -514,9 +509,29 @@
   add_custom_target(${name}-clobber
     DEPENDS ${CMAKE_CURRENT_BINARY_DIR}/${name}-clobber-stamp)
 
-  if(CMAKE_SYSROOT)
-    set(sysroot_arg -DCMAKE_SYSROOT=${CMAKE_SYSROOT})
-  endif()
+  set(PASSTHROUGH_VARIABLES
+    CMAKE_C_COMPILER_TARGET
+    CMAKE_CXX_COMPILER_TARGET
+    CMAKE_INSTALL_PREFIX
+    CMAKE_MAKE_PROGRAM
+    CMAKE_LINKER
+    CMAKE_AR
+    CMAKE_RANLIB
+    CMAKE_NM
+    CMAKE_OBJCOPY
+    CMAKE_OBJDUMP
+    CMAKE_STRIP
+    CMAKE_SYSROOT
+    CMAKE_SYSTEM_NAME)
+  foreach(variable ${PASSTHROUGH_VARIABLES})
+    if(${variable})
+      list(APPEND CMAKE_PASSTHROUGH_VARIABLES -D${variable}=${${variable}})
+    endif()
+  endforeach()
+
+  string(REPLACE ";" " " FLAGS_STRING "${LIBCXX_CFLAGS}")
+  set(LIBCXX_C_FLAGS "${FLAGS_STRING}")
+  set(LIBCXX_CXX_FLAGS "${FLAGS_STRING}")
 
   ExternalProject_Add(${name}
     DEPENDS ${name}-clobber ${LIBCXX_DEPS}
@@ -524,13 +539,11 @@
     SOURCE_DIR ${COMPILER_RT_LIBCXX_PATH}
     STAMP_DIR ${STAMP_DIR}
     BINARY_DIR ${BINARY_DIR}
-    CMAKE_ARGS -DCMAKE_MAKE_PROGRAM=${CMAKE_MAKE_PROGRAM}
+    CMAKE_ARGS ${CMAKE_PASSTHROUGH_VARIABLES}
                ${compiler_args}
-               ${sysroot_arg}
                -DCMAKE_C_FLAGS=${LIBCXX_C_FLAGS}
                -DCMAKE_CXX_FLAGS=${LIBCXX_CXX_FLAGS}
                -DCMAKE_BUILD_TYPE=Release
-               -DCMAKE_INSTALL_PREFIX=${CMAKE_INSTALL_PREFIX}
                -DLLVM_PATH=${LLVM_MAIN_SRC_DIR}
                -DLLVM_BINARY_DIR=${prefix}
                -DLLVM_LIBRARY_OUTPUT_INTDIR=${prefix}/lib
Index: compiler-rt/trunk/lib/fuzzer/CMakeLists.txt
===================================================================
--- compiler-rt/trunk/lib/fuzzer/CMakeLists.txt
+++ compiler-rt/trunk/lib/fuzzer/CMakeLists.txt
@@ -105,6 +105,7 @@
              -fvisibility=hidden
       CMAKE_ARGS -DCMAKE_CXX_COMPILER_WORKS=ON
                  -DLIBCXX_ENABLE_EXCEPTIONS=OFF
+                 -DLIBCXX_ENABLE_SHARED=OFF
                  -DLIBCXX_CXX_ABI=none)
     target_compile_options(RTfuzzer.${arch} PRIVATE -isystem ${LIBCXX_${arch}_PREFIX}/include/c++/v1)
     add_dependencies(RTfuzzer.${arch} libcxx_fuzzer_${arch}-build)