Index: CMakeLists.txt
===================================================================
--- CMakeLists.txt
+++ CMakeLists.txt
@@ -36,6 +36,8 @@
 mark_as_advanced(COMPILER_RT_BUILD_SANITIZERS)
 option(COMPILER_RT_BUILD_XRAY "Build xray" ON)
 mark_as_advanced(COMPILER_RT_BUILD_XRAY)
+option(COMPILER_RT_BUILD_LIBFUZZER "Build libFuzzer" ON)
+mark_as_advanced(COMPILER_RT_BUILD_LIBFUZZER)
 option(COMPILER_RT_BUILD_XRAY_NO_PREINIT "Build xray with no preinit patching" OFF)
 mark_as_advanced(COMPILER_RT_BUILD_XRAY_NO_PREINIT)
 
Index: cmake/Modules/AddCompilerRT.cmake
===================================================================
--- cmake/Modules/AddCompilerRT.cmake
+++ cmake/Modules/AddCompilerRT.cmake
@@ -202,10 +202,10 @@
     set_target_properties(${libname} PROPERTIES
         OUTPUT_NAME ${output_name_${libname}})
     set_target_properties(${libname} PROPERTIES FOLDER "Compiler-RT Runtime")
+    if(LIB_LINK_LIBS)
+      target_link_libraries(${libname} ${LIB_LINK_LIBS})
+    endif()
     if(${type} STREQUAL "SHARED")
-      if(LIB_LINK_LIBS)
-        target_link_libraries(${libname} ${LIB_LINK_LIBS})
-      endif()
       if(WIN32 AND NOT CYGWIN AND NOT MINGW)
         set_target_properties(${libname} PROPERTIES IMPORT_PREFIX "")
         set_target_properties(${libname} PROPERTIES IMPORT_SUFFIX ".lib")
@@ -368,6 +368,7 @@
     set(TEST_LINK_FLAGS "${CMAKE_EXE_LINKER_FLAGS} ${TEST_LINK_FLAGS}")
     separate_arguments(TEST_LINK_FLAGS)
   endif()
+
   add_custom_target(${test_name}
     COMMAND ${COMPILER_RT_TEST_COMPILER} ${TEST_OBJECTS}
             -o "${output_bin}"
Index: cmake/base-config-ix.cmake
===================================================================
--- cmake/base-config-ix.cmake
+++ cmake/base-config-ix.cmake
@@ -4,6 +4,8 @@
 # runtime libraries.
 
 include(CheckIncludeFile)
+include(CheckCXXSourceCompiles)
+
 check_include_file(unwind.h HAVE_UNWIND_H)
 
 # Top level target used to build all compiler-rt libraries.
@@ -86,6 +88,17 @@
   option(COMPILER_RT_ENABLE_IOS "Enable building for iOS" On)
   option(COMPILER_RT_ENABLE_WATCHOS "Enable building for watchOS - Experimental" Off)
   option(COMPILER_RT_ENABLE_TVOS "Enable building for tvOS - Experimental" Off)
+
+  CHECK_CXX_SOURCE_COMPILES("
+      static thread_local int blah;
+      int main() {
+        return 0;
+      }
+      " HAS_THREAD_LOCAL)
+
+  if( NOT HAS_THREAD_LOCAL )
+    set(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} -Dthread_local=__thread")
+  endif()
 else()
   option(COMPILER_RT_DEFAULT_TARGET_ONLY "Build builtins only for the default target" Off)
 endif()
Index: cmake/config-ix.cmake
===================================================================
--- cmake/config-ix.cmake
+++ cmake/config-ix.cmake
@@ -194,6 +194,7 @@
 set(ALL_ASAN_SUPPORTED_ARCH ${X86} ${X86_64} ${ARM32} ${ARM64}
     ${MIPS32} ${MIPS64} ${PPC64} ${S390X})
 set(ALL_DFSAN_SUPPORTED_ARCH ${X86_64} ${MIPS64} ${ARM64})
+set(ALL_FUZZER_SUPPORTED_ARCH x86_64)
 
 if(APPLE)
   set(ALL_LSAN_SUPPORTED_ARCH ${X86} ${X86_64} ${MIPS64} ${ARM64})
@@ -413,7 +414,11 @@
     SANITIZER_COMMON_SUPPORTED_ARCH)
   list_intersect(XRAY_SUPPORTED_ARCH
     ALL_XRAY_SUPPORTED_ARCH
-		SANITIZER_COMMON_SUPPORTED_ARCH)
+    SANITIZER_COMMON_SUPPORTED_ARCH)
+  list_intersect(FUZZER_SUPPORTED_ARCH
+    ALL_FUZZER_SUPPORTED_ARCH
+    ALL_SANITIZER_COMMON_SUPPORTED_ARCH)
+
 else()
   # Architectures supported by compiler-rt libraries.
   filter_available_targets(SANITIZER_COMMON_SUPPORTED_ARCH
@@ -425,6 +430,7 @@
   filter_available_targets(UBSAN_COMMON_SUPPORTED_ARCH
     ${SANITIZER_COMMON_SUPPORTED_ARCH})
   filter_available_targets(ASAN_SUPPORTED_ARCH ${ALL_ASAN_SUPPORTED_ARCH})
+  filter_available_targets(FUZZER_SUPPORTED_ARCH ${ALL_FUZZER_SUPPORTED_ARCH})
   filter_available_targets(DFSAN_SUPPORTED_ARCH ${ALL_DFSAN_SUPPORTED_ARCH})
   filter_available_targets(LSAN_SUPPORTED_ARCH ${ALL_LSAN_SUPPORTED_ARCH})
   filter_available_targets(MSAN_SUPPORTED_ARCH ${ALL_MSAN_SUPPORTED_ARCH})
@@ -573,3 +579,10 @@
 else()
   set(COMPILER_RT_HAS_XRAY FALSE)
 endif()
+
+if (COMPILER_RT_HAS_SANITIZER_COMMON AND FUZZER_SUPPORTED_ARCH AND
+      OS_NAME MATCHES "Darwin|Linux")
+  set(COMPILER_RT_HAS_FUZZER TRUE)
+else()
+  set(COMPILER_RT_HAS_FUZZER FALSE)
+endif()
Index: lib/CMakeLists.txt
===================================================================
--- lib/CMakeLists.txt
+++ lib/CMakeLists.txt
@@ -46,3 +46,7 @@
 if(COMPILER_RT_BUILD_XRAY)
   compiler_rt_build_runtime(xray)
 endif()
+
+if(COMPILER_RT_BUILD_LIBFUZZER)
+  compiler_rt_build_runtime(fuzzer)
+endif()
Index: lib/fuzzer/CMakeLists.txt
===================================================================
--- lib/fuzzer/CMakeLists.txt
+++ lib/fuzzer/CMakeLists.txt
@@ -1,77 +1,63 @@
-include(CheckCXXSourceCompiles)
-
-if( APPLE )
-  CHECK_CXX_SOURCE_COMPILES("
-      static thread_local int blah;
-      int main() {
-        return 0;
-      }
-      " HAS_THREAD_LOCAL)
-
-  if( NOT HAS_THREAD_LOCAL )
-    set(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} -Dthread_local=__thread")
-  endif()
-endif()
-
-if (CMAKE_SYSTEM_NAME MATCHES "Darwin|Linux")
-  set(LIBFUZZER_ENABLED_CHECK ON)
-else()
-  set(LIBFUZZER_ENABLED_CHECK OFF)
+set(LIBFUZZER_SOURCES
+  FuzzerCrossOver.cpp
+  FuzzerDriver.cpp
+  FuzzerExtFunctionsDlsym.cpp
+  FuzzerExtFunctionsDlsymWin.cpp
+  FuzzerExtFunctionsWeak.cpp
+  FuzzerExtraCounters.cpp
+  FuzzerIO.cpp
+  FuzzerIOPosix.cpp
+  FuzzerIOWindows.cpp
+  FuzzerLoop.cpp
+  FuzzerMerge.cpp
+  FuzzerMutate.cpp
+  FuzzerSHA1.cpp
+  FuzzerShmemPosix.cpp
+  FuzzerShmemWindows.cpp
+  FuzzerTracePC.cpp
+  FuzzerUtil.cpp
+  FuzzerUtilDarwin.cpp
+  FuzzerUtilLinux.cpp
+  FuzzerUtilPosix.cpp
+  FuzzerUtilWindows.cpp
+  )
+
+if (CMAKE_CXX_FLAGS MATCHES "fsanitize-coverage")
+  set(LIBFUZZER_CFLAGS -fno-sanitize-coverage=trace-pc-guard,edge,trace-cmp,indirect-calls,8bit-counters)
 endif()
 
-# Compile libFuzzer if the compilation is specifically requested, OR
-# if the platform is known to be working.
-set(LIBFUZZER_ENABLE ${LIBFUZZER_ENABLED_CHECK} CACHE BOOL "Build libFuzzer and its tests")
-set(LIBFUZZER_ENABLE_TESTS OFF CACHE BOOL "Build libFuzzer and its tests")
-
-if (LLVM_USE_SANITIZE_COVERAGE)
-  set(CMAKE_CXX_FLAGS
-    "${CMAKE_CXX_FLAGS} -fno-sanitize-coverage=trace-pc-guard,edge,trace-cmp,indirect-calls,8bit-counters -Werror")
-endif()
-
-if (LIBFUZZER_ENABLE)
-  add_library(LLVMFuzzerNoMainObjects OBJECT
-      FuzzerCrossOver.cpp
-      FuzzerDriver.cpp
-      FuzzerExtFunctionsDlsym.cpp
-      FuzzerExtFunctionsDlsymWin.cpp
-      FuzzerExtFunctionsWeak.cpp
-      FuzzerExtraCounters.cpp
-      FuzzerIO.cpp
-      FuzzerIOPosix.cpp
-      FuzzerIOWindows.cpp
-      FuzzerLoop.cpp
-      FuzzerMerge.cpp
-      FuzzerMutate.cpp
-      FuzzerSHA1.cpp
-      FuzzerShmemPosix.cpp
-      FuzzerShmemWindows.cpp
-      FuzzerTracePC.cpp
-      FuzzerUtil.cpp
-      FuzzerUtilDarwin.cpp
-      FuzzerUtilLinux.cpp
-      FuzzerUtilPosix.cpp
-      FuzzerUtilWindows.cpp
-      )
-  add_library(LLVMFuzzerNoMain STATIC
-      $<TARGET_OBJECTS:LLVMFuzzerNoMainObjects>
-      )
-  target_link_libraries(LLVMFuzzerNoMain ${LLVM_PTHREAD_LIB})
-  add_library(LLVMFuzzer STATIC
-      FuzzerMain.cpp
-      $<TARGET_OBJECTS:LLVMFuzzerNoMainObjects>
-      )
-  target_link_libraries(LLVMFuzzer ${LLVM_PTHREAD_LIB})
+if(APPLE)
+  set(FUZZER_SUPPORTED_OS osx)
 endif()
 
-if (MSVC)
-
-  # Until bots are reconfigured, check-fuzzer on Windows is a no-OP.
-  add_custom_target(check-fuzzer)
-  add_custom_command(TARGET check-fuzzer
-    COMMAND cmake -E echo "check-fuzzer is disalbed on Windows")
-else()
-  if (LLVM_INCLUDE_TESTS AND LIBFUZZER_ENABLE_TESTS)
-    add_subdirectory(test)
-  endif()
+add_compiler_rt_object_libraries(RTfuzzer
+  OS ${FUZZER_SUPPORTED_OS}
+  ARCHS ${FUZZER_SUPPORTED_ARCH}
+  SOURCES ${LIBFUZZER_SOURCES}
+  CFLAGS ${LIBFUZZER_CFLAGS})
+
+add_compiler_rt_object_libraries(RTfuzzer_main
+  OS ${FUZZER_SUPPORTED_OS}
+  ARCHS ${FUZZER_SUPPORTED_ARCH}
+  SOURCES FuzzerMain.cpp
+  CFLAGS ${LIBFUZZER_CFLAGS})
+
+add_compiler_rt_runtime(clang_rt.fuzzer
+  STATIC
+  OS ${FUZZER_SUPPORTED_OS}
+  ARCHS ${FUZZER_SUPPORTED_ARCH}
+  OBJECT_LIBS RTfuzzer RTfuzzer_main
+  CFLAGS ${LIBFUZZER_CFLAGS}
+  PARENT_TARGET fuzzer)
+
+add_compiler_rt_runtime(clang_rt.fuzzer_no_main
+  STATIC
+  OS ${FUZZER_SUPPORTED_OS}
+  ARCHS ${FUZZER_SUPPORTED_ARCH}
+  OBJECT_LIBS RTfuzzer
+  CFLAGS ${LIBFUZZER_CFLAGS}
+  PARENT_TARGET fuzzer)
+
+if(COMPILER_RT_INCLUDE_TESTS)
+  add_subdirectory(tests)
 endif()
Index: lib/fuzzer/test/CMakeLists.txt
===================================================================
--- lib/fuzzer/test/CMakeLists.txt
+++ /dev/null
@@ -1,66 +0,0 @@
-
-if(APPLE)
-  # LeakSanitizer is not supported on OSX and Windows right now
-  set(HAS_LSAN 0)
-  message(WARNING "LeakSanitizer is not supported."
-    " Building and running LibFuzzer LeakSanitizer tests is disabled."
-    )
-else()
-  set(HAS_LSAN 1)
-endif()
-
-###############################################################################
-# Unit tests
-###############################################################################
-
-add_custom_target(FuzzerUnitTests)
-set_target_properties(FuzzerUnitTests PROPERTIES FOLDER "libFuzzer tests")
-
-add_executable(LLVMFuzzer-Unittest FuzzerUnittest.cpp)
-
-target_link_libraries(LLVMFuzzer-Unittest
-  gtest
-  gtest_main
-  LLVMFuzzerNoMain
-  )
-
-target_include_directories(LLVMFuzzer-Unittest PRIVATE
-  "${LLVM_MAIN_SRC_DIR}/utils/unittest/googletest/include"
-  )
-
-set_target_properties(LLVMFuzzer-Unittest
-  PROPERTIES RUNTIME_OUTPUT_DIRECTORY
-  "${CMAKE_CURRENT_BINARY_DIR}"
-)
-
-include_directories(..)
-
-###############################################################################
-# Configure lit to run the tests
-#
-# Note this is done after declaring all tests so we can inform lit if any tests
-# need to be disabled.
-###############################################################################
-
-# Use just-built Clang to compile/link tests on all platforms, except for
-# Windows where we need to use clang-cl instead.
-set(LIBFUZZER_TEST_COMPILER ${LLVM_RUNTIME_OUTPUT_INTDIR}/clang)
-set(LIBFUZZER_TEST_CXX_COMPILER ${LLVM_RUNTIME_OUTPUT_INTDIR}/clang++)
-
-# LIT-based libFuzzer tests.
-configure_lit_site_cfg(
-  ${CMAKE_CURRENT_SOURCE_DIR}/lit.site.cfg.in
-  ${CMAKE_CURRENT_BINARY_DIR}/lit.site.cfg
-  )
-
-# libFuzzer unit tests.
-configure_lit_site_cfg(
-  ${CMAKE_CURRENT_SOURCE_DIR}/unit/lit.site.cfg.in
-  ${CMAKE_CURRENT_BINARY_DIR}/unit/lit.site.cfg
-  )
-
-add_lit_testsuite(check-fuzzer "Running Fuzzer tests"
-  ${CMAKE_CURRENT_BINARY_DIR}
-  DEPENDS LLVMFuzzer-Unittest)
-
-add_dependencies(check-fuzzer LLVMFuzzer asan clang llvm-symbolizer FileCheck sancov not)
Index: lib/fuzzer/test/unit/lit.cfg
===================================================================
--- lib/fuzzer/test/unit/lit.cfg
+++ /dev/null
@@ -1,7 +0,0 @@
-import lit.formats
-
-config.name = "LLVMFuzzer-Unittest"
-print config.test_exec_root
-config.test_format = lit.formats.GoogleTest(".", "Unittest")
-config.suffixes = []
-config.test_source_root = config.test_exec_root
Index: lib/fuzzer/test/unit/lit.site.cfg.in
===================================================================
--- lib/fuzzer/test/unit/lit.site.cfg.in
+++ /dev/null
@@ -1,2 +0,0 @@
-config.test_exec_root = "@CMAKE_CURRENT_BINARY_DIR@"
-lit_config.load_config(config, "@CMAKE_CURRENT_SOURCE_DIR@/unit/lit.cfg")
Index: lib/fuzzer/tests/CMakeLists.txt
===================================================================
--- /dev/null
+++ lib/fuzzer/tests/CMakeLists.txt
@@ -0,0 +1,46 @@
+set(LIBFUZZER_UNITTEST_CFLAGS
+  ${COMPILER_RT_UNITTEST_CFLAGS}
+  ${COMPILER_RT_GTEST_CFLAGS}
+  -I${COMPILER_RT_SOURCE_DIR}/lib/fuzzer
+  -fno-rtti
+  -Werror
+  -O2)
+
+add_custom_target(FuzzerUnitTests)
+set_target_properties(FuzzerUnitTests PROPERTIES FOLDER "Compiler-RT Tests")
+
+set(LIBFUZZER_UNITTEST_LINK_FLAGS ${COMPILER_RT_UNITTEST_LINK_FLAGS})
+list(APPEND LIBFUZZER_UNITTEST_LINK_FLAGS --driver-mode=g++)
+
+if(APPLE)
+  list(APPEND LIBFUZZER_UNITTEST_LINK_FLAGS -lc++)
+else()
+  list(APPEND LIBFUZZER_UNITTEST_LINK_FLAGS -lstdc++)
+endif()
+
+foreach(arch ${FUZZER_SUPPORTED_ARCH})
+  set(LIBFUZZER_TEST_RUNTIME RTFuzzerTest.${arch})
+  if(APPLE)
+    set(LIBFUZZER_TEST_RUNTIME_OBJECTS
+      $<TARGET_OBJECTS:RTfuzzer.osx>)
+  else()
+    set(LIBFUZZER_TEST_RUNTIME_OBJECTS
+      $<TARGET_OBJECTS:RTfuzzer.${arch}>)
+  endif()
+  add_library(${LIBFUZZER_TEST_RUNTIME} STATIC
+    ${LIBFUZZER_TEST_RUNTIME_OBJECTS})
+  set_target_properties(${LIBFUZZER_TEST_RUNTIME} PROPERTIES
+    ARCHIVE_OUTPUT_DIRECTORY ${CMAKE_CURRENT_BINARY_DIR}
+    FOLDER "Compiler-RT Runtime tests")
+
+  set(FuzzerTestObjects)
+  generate_compiler_rt_tests(FuzzerTestObjects
+    FuzzerUnitTests "Fuzzer-${arch}-Test" ${arch}
+    SOURCES FuzzerUnittest.cpp ${COMPILER_RT_GTEST_SOURCE}
+    RUNTIME ${LIBFUZZER_TEST_RUNTIME}
+    DEPS gtest
+    CFLAGS ${LIBFUZZER_UNITTEST_CFLAGS}
+    LINK_FLAGS ${LIBFUZZER_UNITTEST_LINK_FLAGS})
+  set_target_properties(FuzzerUnitTests PROPERTIES
+    RUNTIME_OUTPUT_DIRECTORY ${CMAKE_CURRENT_BINARY_DIR})
+endforeach()
Index: lib/fuzzer/tests/FuzzerUnittest.cpp
===================================================================
--- lib/fuzzer/tests/FuzzerUnittest.cpp
+++ lib/fuzzer/tests/FuzzerUnittest.cpp
@@ -761,3 +761,8 @@
               {135, 5}, {137, 6}, {146, 7}};
   EXPECT_EQ(Res, Expected);
 }
+
+int main(int argc, char **argv) {
+  testing::InitGoogleTest(&argc, argv);
+  return RUN_ALL_TESTS();
+}
Index: test/CMakeLists.txt
===================================================================
--- test/CMakeLists.txt
+++ test/CMakeLists.txt
@@ -58,6 +58,7 @@
     # CFI tests require diagnostic mode, which is implemented in UBSan.
     compiler_rt_test_runtime(ubsan cfi)
     compiler_rt_test_runtime(sanitizer_common)
+    compiler_rt_test_runtime(fuzzer)
 
     foreach(sanitizer ${COMPILER_RT_SANITIZERS_TO_BUILD})
       # cfi testing is gated on ubsan
Index: test/fuzzer/CMakeLists.txt
===================================================================
--- /dev/null
+++ test/fuzzer/CMakeLists.txt
@@ -0,0 +1,40 @@
+
+set(LIBFUZZER_TEST_DEPS ${SANITIZER_COMMON_LIT_TEST_DEPS})
+if (NOT COMPILER_RT_STANDALONE_BUILD)
+  list(APPEND LIBFUZZER_TEST_DEPS fuzzer)
+endif()
+
+if(COMPILER_RT_INCLUDE_TESTS)
+  list(APPEND LIBFUZZER_TEST_DEPS FuzzerUnitTests)
+endif()
+
+set(LIBFUZZER_TESTSUITES)
+
+
+if(COMPILER_RT_INCLUDE_TESTS)
+  # libFuzzer unit tests.
+  configure_lit_site_cfg(
+    ${CMAKE_CURRENT_SOURCE_DIR}/unit/lit.site.cfg.in
+    ${CMAKE_CURRENT_BINARY_DIR}/unit/lit.site.cfg)
+  list(APPEND LIBFUZZER_TESTSUITES ${CMAKE_CURRENT_BINARY_DIR}/unit)
+endif()
+
+foreach(arch ${FUZZER_SUPPORTED_ARCH})
+  get_test_cc_for_arch(${arch} LIBFUZZER_TEST_COMPILER LIBFUZZER_TEST_FLAGS)
+
+  string(TOUPPER ${arch} ARCH_UPPER_CASE)
+  set(CONFIG_NAME ${ARCH_UPPER_CASE}${OS_NAME}Config)
+
+   #LIT-based libFuzzer tests.
+  configure_lit_site_cfg(
+    ${CMAKE_CURRENT_SOURCE_DIR}/lit.site.cfg.in
+    ${CMAKE_CURRENT_BINARY_DIR}/${CONFIG_NAME}/lit.site.cfg
+    )
+  list(APPEND LIBFUZZER_TESTSUITES ${CMAKE_CURRENT_BINARY_DIR}/${CONFIG_NAME})
+
+endforeach()
+
+add_lit_testsuite(check-fuzzer "Running Fuzzer tests"
+  ${LIBFUZZER_TESTSUITES}
+  DEPENDS ${LIBFUZZER_TEST_DEPS})
+set_target_properties(check-fuzzer PROPERTIES FOLDER "Compiler-RT Tests")
Index: test/fuzzer/afl-driver-extra-stats.test
===================================================================
--- test/fuzzer/afl-driver-extra-stats.test
+++ test/fuzzer/afl-driver-extra-stats.test
@@ -1,4 +1,4 @@
-RUN: %no_fuzzer_cpp_compiler -fno-sanitize-coverage=edge,trace-cmp,indirect-calls,8bit-counters,trace-pc-guard %S/AFLDriverTest.cpp %S/../afl/afl_driver.cpp -o %t-AFLDriverTest
+RUN: %no_fuzzer_cpp_compiler -fno-sanitize-coverage=edge,trace-cmp,indirect-calls,8bit-counters,trace-pc-guard %S/AFLDriverTest.cpp %libfuzzer_src/afl/afl_driver.cpp -o %t-AFLDriverTest
 
 ; Test that not specifying an extra stats file isn't broken.
 RUN: unset AFL_DRIVER_EXTRA_STATS_FILENAME
Index: test/fuzzer/afl-driver-stderr.test
===================================================================
--- test/fuzzer/afl-driver-stderr.test
+++ test/fuzzer/afl-driver-stderr.test
@@ -1,4 +1,4 @@
-RUN: %no_fuzzer_cpp_compiler -fno-sanitize-coverage=edge,trace-cmp,indirect-calls,8bit-counters,trace-pc-guard %S/AFLDriverTest.cpp %S/../afl/afl_driver.cpp -o %t-AFLDriverTest
+RUN: %no_fuzzer_cpp_compiler -fno-sanitize-coverage=edge,trace-cmp,indirect-calls,8bit-counters,trace-pc-guard %S/AFLDriverTest.cpp %libfuzzer_src/afl/afl_driver.cpp -o %t-AFLDriverTest
 
 ; Test that not specifying a stderr file isn't broken.
 RUN: unset AFL_DRIVER_STDERR_DUPLICATE_FILENAME
Index: test/fuzzer/afl-driver.test
===================================================================
--- test/fuzzer/afl-driver.test
+++ test/fuzzer/afl-driver.test
@@ -1,6 +1,6 @@
 REQUIRES: linux
 
-RUN: %no_fuzzer_cpp_compiler -fno-sanitize-coverage=edge,trace-cmp,indirect-calls,8bit-counters,trace-pc-guard %S/AFLDriverTest.cpp %S/../afl/afl_driver.cpp -o %t-AFLDriverTest
+RUN: %no_fuzzer_cpp_compiler -fno-sanitize-coverage=edge,trace-cmp,indirect-calls,8bit-counters,trace-pc-guard %S/AFLDriverTest.cpp %libfuzzer_src/afl/afl_driver.cpp -o %t-AFLDriverTest
 
 RUN: echo -n "abc" > %t.file3
 RUN: echo -n "abcd" > %t.file4
Index: test/fuzzer/lit.cfg
===================================================================
--- test/fuzzer/lit.cfg
+++ test/fuzzer/lit.cfg
@@ -1,5 +1,6 @@
 import lit.formats
 import sys
+import os
 
 config.name = "LLVMFuzzer"
 config.test_format = lit.formats.ShTest(True)
@@ -23,19 +24,12 @@
 # the test runner updated.
 config.test_format = lit.formats.ShTest(execute_external)
 
-# Tweak PATH to include llvm tools dir and current exec dir.
-llvm_tools_dir = getattr(config, 'llvm_tools_dir', None)
-if (not llvm_tools_dir) or (not os.path.exists(llvm_tools_dir)):
-  lit_config.fatal("Invalid llvm_tools_dir config attribute: %r" % llvm_tools_dir)
-path = os.path.pathsep.join((llvm_tools_dir, config.test_exec_root,
-                             config.environment['PATH']))
-config.environment['PATH'] = path
-
-if config.has_lsan:
+# LeakSanitizer is not supported on OSX right now.
+if sys.platform.startswith('darwin'):
+  lit_config.note('lsan feature unavailable')
+else:
   lit_config.note('lsan feature available')
   config.available_features.add('lsan')
-else:
-  lit_config.note('lsan feature unavailable')
 
 if sys.platform.startswith('win') or sys.platform.startswith('cygwin'):
   config.available_features.add('windows')
@@ -52,9 +46,12 @@
   lit_config.note('linux feature unavailable')
 
 config.substitutions.append(('%build_dir', config.cmake_binary_dir))
+libfuzzer_src_root = os.path.join(config.compiler_rt_src_root, "lib", "fuzzer")
+config.substitutions.append(('%libfuzzer_src', libfuzzer_src_root))
 
 def generate_compiler_cmd(is_cpp=True, fuzzer_enabled=True):
-  compiler_cmd = config.cpp_compiler if is_cpp else config.c_compiler
+  compiler_cmd = config.c_compiler
+  link_cmd = '-lc++' if 'darwin' in config.target_triple else '-lstdc++'
   std_cmd = '-std=c++11' if is_cpp else ''
   sanitizers = ['address']
   if fuzzer_enabled:
@@ -62,9 +59,9 @@
   sanitizers_cmd = ('-fsanitize=%s' % ','.join(sanitizers))
   isysroot_cmd = ('-isysroot %s' % config.osx_sysroot
       ) if 'darwin' in config.target_triple else ''
-  include_cmd = '-I%s/../.' % config.test_source_root
-  return '%s %s -gline-tables-only %s %s %s' % (
-      compiler_cmd, std_cmd, isysroot_cmd, sanitizers_cmd, include_cmd)
+  include_cmd = '-I%s' % libfuzzer_src_root
+  return '%s %s %s -gline-tables-only %s %s %s' % (
+      compiler_cmd, std_cmd, link_cmd, isysroot_cmd, sanitizers_cmd, include_cmd)
 
 config.substitutions.append(('%cpp_compiler',
       generate_compiler_cmd(is_cpp=True, fuzzer_enabled=True)
Index: test/fuzzer/lit.site.cfg.in
===================================================================
--- test/fuzzer/lit.site.cfg.in
+++ test/fuzzer/lit.site.cfg.in
@@ -1,9 +1,17 @@
+@LIT_SITE_CFG_IN_HEADER@
+
 config.test_exec_root = "@CMAKE_CURRENT_BINARY_DIR@"
-config.llvm_tools_dir = "@LLVM_TOOLS_DIR@"
-config.has_lsan = True if @HAS_LSAN@ == 1 else False
-config.cpp_compiler = "@LIBFUZZER_TEST_CXX_COMPILER@"
+
+config.cpp_compiler = "@LIBFUZZER_TEST_COMPILER@"
+config.target_flags = "@LIBFUZZER_TEST_FLAGS@"
 config.c_compiler = "@LIBFUZZER_TEST_COMPILER@"
+
 config.osx_sysroot = "@CMAKE_OSX_SYSROOT@"
 config.cmake_binary_dir = "@CMAKE_BINARY_DIR@"
 config.target_triple = "@TARGET_TRIPLE@"
+
+# Load common config for all compiler-rt lit tests.
+lit_config.load_config(config,
+    "@COMPILER_RT_BINARY_DIR@/test/lit.common.configured")
+
 lit_config.load_config(config, "@CMAKE_CURRENT_SOURCE_DIR@/lit.cfg")
Index: test/fuzzer/standalone.test
===================================================================
--- test/fuzzer/standalone.test
+++ test/fuzzer/standalone.test
@@ -1,4 +1,4 @@
-RUN: %no_fuzzer_c_compiler %S/../standalone/StandaloneFuzzTargetMain.c -c -o %t_1.o
+RUN: %no_fuzzer_c_compiler %libfuzzer_src/standalone/StandaloneFuzzTargetMain.c -c -o %t_1.o
 RUN: %no_fuzzer_cpp_compiler %S/InitializeTest.cpp -c -o %t_2.o
 
 RUN: %no_fuzzer_cpp_compiler %t_1.o %t_2.o %build_dir/lib/libLLVMFuzzerNoMain.a -o %t-StandaloneInitializeTest
Index: test/fuzzer/unit/lit.site.cfg.in
===================================================================
--- /dev/null
+++ test/fuzzer/unit/lit.site.cfg.in
@@ -0,0 +1,9 @@
+@LIT_SITE_CFG_IN_HEADER@
+
+config.name = "LLVMFuzzer-Unittest"
+# Load common config for all compiler-rt unit tests.
+lit_config.load_config(config, "@COMPILER_RT_BINARY_DIR@/unittests/lit.common.unit.configured")
+
+config.test_exec_root = os.path.join("@COMPILER_RT_BINARY_DIR@",
+                                     "lib", "fuzzer", "tests")
+config.test_source_root = config.test_exec_root