diff --git a/libcxx/utils/libcxx/test/config.py b/libcxx/utils/libcxx/test/config.py
--- a/libcxx/utils/libcxx/test/config.py
+++ b/libcxx/utils/libcxx/test/config.py
@@ -175,7 +175,7 @@
         # Gather various compiler parameters.
         cxx = self.get_lit_conf('cxx_under_test')
         self.cxx_is_clang_cl = cxx is not None and \
-                               os.path.basename(cxx) == 'clang-cl.exe'
+                               os.path.basename(cxx).startswith('clang-cl')
         # If no specific cxx_under_test was given, attempt to infer it as
         # clang++.
         if cxx is None or self.cxx_is_clang_cl:
diff --git a/libcxx/utils/libcxx/test/target_info.py b/libcxx/utils/libcxx/test/target_info.py
--- a/libcxx/utils/libcxx/test/target_info.py
+++ b/libcxx/utils/libcxx/test/target_info.py
@@ -187,6 +187,9 @@
     def __init__(self, full_config):
         super(WindowsLocalTI, self).__init__(full_config)
 
+    def is_windows(self):
+        return True
+
 class MingwLocalTI(WindowsLocalTI):
     def __init__(self, full_config):
         super(MingwLocalTI, self).__init__(full_config)