Index: CMakeLists.txt
===================================================================
--- CMakeLists.txt
+++ CMakeLists.txt
@@ -131,6 +131,8 @@
 
 if("${COMPILER_RT_TEST_COMPILER}" MATCHES "clang[+]*$")
   set(COMPILER_RT_TEST_COMPILER_ID Clang)
+elseif("${COMPILER_RT_TEST_COMPILER}" MATCHES "clang-cl.exe$")
+  set(COMPILER_RT_TEST_COMPILER_ID Clang)
 else()
   set(COMPILER_RT_TEST_COMPILER_ID GNU)
 endif()
Index: test/asan/TestCases/Windows/lit.local.cfg
===================================================================
--- /dev/null
+++ test/asan/TestCases/Windows/lit.local.cfg
@@ -0,0 +1,14 @@
+def getRoot(config):
+  if not config.parent:
+    return config
+  return getRoot(config.parent)
+
+root = getRoot(config)
+
+# We only run a small set of tests on Windows for now.
+# Override the parent directory's "unsupported" decision until we can handle
+# all of its tests.
+if root.host_os in ['Windows']:
+  config.unsupported = False
+else:
+  config.unsupported = True
Index: test/asan/TestCases/Windows/thread_stack_array_left_oob.cc
===================================================================
--- /dev/null
+++ test/asan/TestCases/Windows/thread_stack_array_left_oob.cc
@@ -0,0 +1,26 @@
+// RUN: %clangxx_asan -O0 %s -Fe%t 2>&1
+// 'cat' is used below to work around FileCheck buffering bug which makes this
+// test flaky.  FIXME: file an issue.
+// RUN: not %run %t 2>&1 | cat | FileCheck %s --check-prefix=CHECK
+
+#include <windows.h>
+
+DWORD WINAPI thread_proc(void *context) {
+  int subscript = -1;
+  volatile char stack_buffer[42];
+  stack_buffer[subscript] = 42;
+// CHECK: AddressSanitizer: stack-buffer-overflow on address [[ADDR:0x[0-9a-f]+]]
+// CHECK: WRITE of size 1 at [[ADDR]] thread T1
+// CHECK:   {{#0 .* thread_proc .*thread_stack_array_left_oob.cc}}:[[@LINE-3]]
+// CHECK: Address [[ADDR]] is located in stack of thread T1 at offset {{.*}} in frame
+// CHECK:   thread_proc
+  return 0;
+}
+
+int main(void) {
+  HANDLE thr = CreateThread(NULL, 0, thread_proc, NULL, 0, NULL);
+// CHECK: Thread T1 created by T0 here:
+// CHECK:   {{#[01] .* main .*thread_stack_array_left_oob.cc}}:[[@LINE-2]]
+  WaitForSingleObject(thr, INFINITE);
+  return 0;
+}
Index: test/asan/lit.cfg
===================================================================
--- test/asan/lit.cfg
+++ test/asan/lit.cfg
@@ -32,11 +32,19 @@
 # FIXME: Review the set of required flags and check if it can be reduced.
 target_cflags = [get_required_attr(config, "target_cflags")] + extra_linkflags
 target_cxxflags = config.cxx_mode_flags + target_cflags
-clang_asan_static_cflags = ["-fsanitize=address",
-                            "-mno-omit-leaf-frame-pointer",
-                            "-fno-omit-frame-pointer",
-                            "-fno-optimize-sibling-calls",
-                            "-g"] + target_cflags
+clang_asan_static_cflags = ["-fsanitize=address"] + target_cflags
+
+clang_path = getattr(config, 'clang', None)
+if clang_path.find("clang-cl") == -1:
+  clang_asan_static_cflags += ["-g",
+                               "-mno-omit-leaf-frame-pointer",
+                               "-fno-omit-frame-pointer",
+                               "-fno-optimize-sibling-calls"]
+else:
+  clang_asan_static_cflags += ["-Zi",
+                               "-Wno-deprecated-declarations",
+                               "-D_HAS_EXCEPTIONS=0"]
+
 clang_asan_static_cxxflags = config.cxx_mode_flags + clang_asan_static_cflags
 
 if config.asan_dynamic:
Index: test/lit.common.cfg
===================================================================
--- test/lit.common.cfg
+++ test/lit.common.cfg
@@ -20,7 +20,10 @@
 
 compiler_id = getattr(config, 'compiler_id', None)
 if compiler_id == "Clang":
-  config.cxx_mode_flags = ["--driver-mode=g++"]
+  if platform.system() != 'Windows':
+    config.cxx_mode_flags = ["--driver-mode=g++"]
+  else:
+    config.cxx_mode_flags = []
 elif compiler_id == 'GNU':
   config.cxx_mode_flags = ["-x c++"]
 else:
@@ -50,6 +53,10 @@
 path = os.path.pathsep.join((llvm_tools_dir, config.environment['PATH']))
 config.environment['PATH'] = path
 
+# Help MSVS link.exe find the standard libraries.
+if platform.system() == 'Windows':
+  config.environment['LIB'] = os.environ['LIB']
+
 # Use ugly construction to explicitly prohibit "clang", "clang++" etc.
 # in RUN lines.
 config.substitutions.append(