diff --git a/libcxx/test/libcxx/transitive_includes.sanitize.py b/libcxx/test/libcxx/transitive_includes.sanitize.py
--- a/libcxx/test/libcxx/transitive_includes.sanitize.py
+++ b/libcxx/test/libcxx/transitive_includes.sanitize.py
@@ -17,11 +17,16 @@
 
 headers = []
 for line in sys.stdin.readlines():
-  match = re.search('c\+\+/v[0-9]+/(.+)', line)
+  # On Windows, the path separators can either be forward slash or backslash.
+  # If it is a backslash, Clang prints it escaped as two consecutive
+  # backslashes, and they need to be escaped in the RE. (Use a raw string for
+  # the pattern to avoid needing another level of escaping on the Python string
+  # literal level.)
+  match = re.search(r'c\+\+(/|\\\\)v[0-9]+(/|\\\\)(.+)', line)
   if not match:
     continue
 
-  header = match.group(1)
+  header = match.group(3)
   if os.path.basename(header).endswith('.h'): # Skip C headers
     continue
 
@@ -30,4 +35,7 @@
 
   headers.append(header)
 
-print('\n'.join(sorted(set(headers))))
+# Write the output to stdout in binary mode, with '\n' linebreaks on all
+# platforms.
+sys.stdout.buffer.write(bytes('\n'.join(sorted(set(headers))), 'ascii'))
+sys.stdout.buffer.write(b'\n')
diff --git a/libcxx/test/libcxx/transitive_includes.sh.cpp b/libcxx/test/libcxx/transitive_includes.sh.cpp
--- a/libcxx/test/libcxx/transitive_includes.sh.cpp
+++ b/libcxx/test/libcxx/transitive_includes.sh.cpp
@@ -31,8 +31,8 @@
 // This test uses --trace-includes, which is not supported by GCC.
 // UNSUPPORTED: gcc
 
-// This test doesn't work on AIX or Windows, but it should. Needs investigation.
-// XFAIL: buildhost=aix, buildhost=windows
+// This test doesn't work on AIX, but it should. Needs investigation.
+// XFAIL: buildhost=aix
 
 // This test is not supported when we remove the transitive includes provided for backwards
 // compatibility. When we bulk-remove them, we'll adjust the includes that are expected by