diff --git a/libcxx/test/std/containers/container.adaptors/container.adaptors.format/format.functions.tests.h b/libcxx/test/std/containers/container.adaptors/container.adaptors.format/format.functions.tests.h
--- a/libcxx/test/std/containers/container.adaptors/container.adaptors.format/format.functions.tests.h
+++ b/libcxx/test/std/containers/container.adaptors/container.adaptors.format/format.functions.tests.h
@@ -600,16 +600,17 @@
   // *** locale-specific form ***
   check(SV("[-42.5, 0, 1.25, 42.5]"), SV("{::L}"), input); // does not require locales present
 #ifndef TEST_HAS_NO_LOCALIZATION
-// TODO FMT Enable with locale testing active
-#  if 0
+#  ifdef TEST_HAS_LOCALE_fr_FR_UTF_8
   std::locale::global(std::locale(LOCALE_fr_FR_UTF_8));
   check(SV("[-42,5, 0, 1,25, 42,5]"), SV("{::L}"), input);
+#  endif
 
+#  ifdef TEST_HAS_LOCALE_en_US_UTF_8
   std::locale::global(std::locale(LOCALE_en_US_UTF_8));
   check(SV("[-42.5, 0, 1.25, 42.5]"), SV("{::L}"), input);
+#  endif
 
   std::locale::global(std::locale::classic());
-#  endif
 #endif // TEST_HAS_NO_LOCALIZATION
 
   // *** type ***
diff --git a/libcxx/test/std/utilities/format/format.range/format.range.fmtset/format.functions.tests.h b/libcxx/test/std/utilities/format/format.range/format.range.fmtset/format.functions.tests.h
--- a/libcxx/test/std/utilities/format/format.range/format.range.fmtset/format.functions.tests.h
+++ b/libcxx/test/std/utilities/format/format.range/format.range.fmtset/format.functions.tests.h
@@ -776,16 +776,17 @@
   // *** locale-specific form ***
   check(SV("{-42.5, 0, 1.25, 42.5}"), SV("{::L}"), input); // does not require locales present
 #ifndef TEST_HAS_NO_LOCALIZATION
-// TODO FMT Enable with locale testing active
-#  if 0
+#  ifdef TEST_HAS_LOCALE_fr_FR_UTF_8
   std::locale::global(std::locale(LOCALE_fr_FR_UTF_8));
   check(SV("{-42,5, 0, 1,25, 42,5}"), SV("{::L}"), input);
+#  endif
 
+#  ifdef TEST_HAS_LOCALE_en_US_UTF_8
   std::locale::global(std::locale(LOCALE_en_US_UTF_8));
   check(SV("{-42.5, 0, 1.25, 42.5}"), SV("{::L}"), input);
+#  endif
 
   std::locale::global(std::locale::classic());
-#  endif
 #endif // TEST_HAS_NO_LOCALIZATION
 
   // *** type ***
diff --git a/libcxx/test/std/utilities/format/format.range/format.range.formatter/format.functions.tests.h b/libcxx/test/std/utilities/format/format.range/format.range.formatter/format.functions.tests.h
--- a/libcxx/test/std/utilities/format/format.range/format.range.formatter/format.functions.tests.h
+++ b/libcxx/test/std/utilities/format/format.range/format.range.formatter/format.functions.tests.h
@@ -587,16 +587,17 @@
   // *** locale-specific form ***
   check(SV("[-42.5, 0, 1.25, 42.5]"), SV("{::L}"), input); // does not require locales present
 #ifndef TEST_HAS_NO_LOCALIZATION
-// TODO FMT Enable with locale testing active
-#  if 0
+#  ifdef TEST_HAS_LOCALE_fr_FR_UTF_8
   std::locale::global(std::locale(LOCALE_fr_FR_UTF_8));
   check(SV("[-42,5, 0, 1,25, 42,5]"), SV("{::L}"), input);
+#  endif
 
+#  ifdef TEST_HAS_LOCALE_en_US_UTF_8
   std::locale::global(std::locale(LOCALE_en_US_UTF_8));
   check(SV("[-42.5, 0, 1.25, 42.5]"), SV("{::L}"), input);
+#  endif
 
   std::locale::global(std::locale::classic());
-#  endif
 #endif // TEST_HAS_NO_LOCALIZATION
 
   // *** type ***
diff --git a/libcxx/test/support/platform_support.h b/libcxx/test/support/platform_support.h
--- a/libcxx/test/support/platform_support.h
+++ b/libcxx/test/support/platform_support.h
@@ -17,6 +17,10 @@
 #include "test_macros.h"
 
 // locale names
+//
+// An alternative would be to only define these macros when the test suceeds,
+// that would result in compilation error instead of runtime errors
+//
 #define LOCALE_en_US_UTF_8     "en_US.UTF-8"
 #define LOCALE_fr_FR_UTF_8     "fr_FR.UTF-8"
 #ifdef __linux__
diff --git a/libcxx/utils/libcxx/test/features.py b/libcxx/utils/libcxx/test/features.py
--- a/libcxx/utils/libcxx/test/features.py
+++ b/libcxx/utils/libcxx/test/features.py
@@ -240,7 +240,8 @@
   # Note: Using alts directly in the lambda body here will bind it to the value at the
   # end of the loop. Assigning it to a default argument works around this issue.
   DEFAULT_FEATURES.append(Feature(name='locale.{}'.format(locale),
-                                  when=lambda cfg, alts=alts: hasAnyLocale(cfg, alts)))
+                                  when=lambda cfg, alts=alts: hasAnyLocale(cfg, alts),
+                                  actions=[AddCompileFlag('-DTEST_HAS_LOCALE_{}'.format(re.sub("\W", "_", locale)))]))
 
 
 # Add features representing the target platform name: darwin, linux, windows, etc...