diff --git a/libcxx/test/libcxx/selftest/dsl/dsl.sh.py b/libcxx/test/libcxx/selftest/dsl/dsl.sh.py
--- a/libcxx/test/libcxx/selftest/dsl/dsl.sh.py
+++ b/libcxx/test/libcxx/selftest/dsl/dsl.sh.py
@@ -6,8 +6,6 @@
 #
 #===----------------------------------------------------------------------===##
 
-# XFAIL: LIBCXX-WINDOWS-FIXME
-
 # Note: We prepend arguments with 'x' to avoid thinking there are too few
 #       arguments in case an argument is an empty string.
 # RUN: %{python} %s x%S x%T x%{substitutions}
@@ -251,7 +249,11 @@
             self.fail("checking for hasLocale should not explode")
 
     def test_nonexistent_locale(self):
-        self.assertFalse(dsl.hasAnyLocale(self.config, ['for_sure_this_is_not_an_existing_locale']))
+        # The original spelling here, "for_sure_this_is_not_an_existing_locale",
+        # is accidentally detected as existing by the Windows UCRT.
+        # https://developercommunity.visualstudio.com/t/setlocale-succeeds-for-bogus-locale-names-in-older/1652241
+        # This is fixed in UCRT/Windows 10.0.18362.0.
+        self.assertFalse(dsl.hasAnyLocale(self.config, ['forsurethisisnotanexistinglocale']))
 
     def test_localization_program_doesnt_compile(self):
         compilerIndex = findIndex(self.config.substitutions, lambda x: x[0] == '%{cxx}')
diff --git a/libcxx/utils/libcxx/test/dsl.py b/libcxx/utils/libcxx/test/dsl.py
--- a/libcxx/utils/libcxx/test/dsl.py
+++ b/libcxx/utils/libcxx/test/dsl.py
@@ -173,6 +173,8 @@
 
     actualOut = re.search("# command output:\n(.+)\n$", out, flags=re.DOTALL)
     actualOut = actualOut.group(1) if actualOut else ""
+    if platform.system() == 'Windows':
+      actualOut = actualOut.replace('\r\n', '\n')
     return actualOut
 
 @_memoizeExpensiveOperation(lambda c, p, args=None: (c.substitutions, c.environment, p, args))