diff --git a/libcxx/src/locale.cpp b/libcxx/src/locale.cpp
--- a/libcxx/src/locale.cpp
+++ b/libcxx/src/locale.cpp
@@ -4541,7 +4541,6 @@
   dest = out;
   return true;
 }
-#endif // _LIBCPP_HAS_NO_WIDE_CHARACTERS
 
 static bool checked_string_to_char_convert(char& dest,
                                            const char* ptr,
@@ -4553,7 +4552,6 @@
     return true;
   }
 
-#ifndef _LIBCPP_HAS_NO_WIDE_CHARACTERS
   // First convert the MBS into a wide char then attempt to narrow it using
   // wctob_l.
   wchar_t wout;
@@ -4574,12 +4572,37 @@
   default:
     return false;
   }
-#else // _LIBCPP_HAS_NO_WIDE_CHARACTERS
-  return false;
-#endif // _LIBCPP_HAS_NO_WIDE_CHARACTERS
   _LIBCPP_UNREACHABLE();
 }
+#else // _LIBCPP_HAS_NO_WIDE_CHARACTERS
+static bool is_narrow_non_breaking_space(const char* ptr) {
+  // https://www.fileformat.info/info/unicode/char/202f/index.htm
+  return ptr[0] == '\xe2' && ptr[1] == '\x80' && ptr[2] == '\xaf';
+}
 
+static bool is_non_breaking_space(const char* ptr) {
+  // https://www.fileformat.info/info/unicode/char/0a/index.htm
+  return ptr[0] == '\xc2' && ptr[1] == '\xa0';
+}
+
+static bool checked_string_to_char_convert(char& dest, const char* ptr, locale_t __loc) {
+  if (*ptr == '\0')
+    return false;
+  if (!ptr[1]) {
+    dest = *ptr;
+    return true;
+  }
+
+  // FIXME: Work around specific multibyte sequences that we can reasonably
+  // translate into a different single byte.
+  if (is_narrow_non_breaking_space(ptr) || is_non_breaking_space(ptr)) {
+    dest = ' ';
+    return true;
+  }
+
+  return false;
+}
+#endif // _LIBCPP_HAS_NO_WIDE_CHARACTERS
 
 // numpunct<char> && numpunct<wchar_t>
 
diff --git a/libcxx/test/std/localization/locale.categories/category.monetary/locale.money.get/locale.money.get.members/get_long_double_fr_FR.pass.cpp b/libcxx/test/std/localization/locale.categories/category.monetary/locale.money.get/locale.money.get.members/get_long_double_fr_FR.pass.cpp
--- a/libcxx/test/std/localization/locale.categories/category.monetary/locale.money.get/locale.money.get.members/get_long_double_fr_FR.pass.cpp
+++ b/libcxx/test/std/localization/locale.categories/category.monetary/locale.money.get/locale.money.get.members/get_long_double_fr_FR.pass.cpp
@@ -13,9 +13,6 @@
 
 // XFAIL: LIBCXX-WINDOWS-FIXME
 
-// TODO(mordante): Investigate these localization/format failures since updating the Docker image in CI
-// UNSUPPORTED: stdlib=libc++
-
 // REQUIRES: locale.fr_FR.UTF-8
 
 // <locale>
diff --git a/libcxx/test/std/localization/locale.categories/category.monetary/locale.money.put/locale.money.put.members/put_long_double_fr_FR.pass.cpp b/libcxx/test/std/localization/locale.categories/category.monetary/locale.money.put/locale.money.put.members/put_long_double_fr_FR.pass.cpp
--- a/libcxx/test/std/localization/locale.categories/category.monetary/locale.money.put/locale.money.put.members/put_long_double_fr_FR.pass.cpp
+++ b/libcxx/test/std/localization/locale.categories/category.monetary/locale.money.put/locale.money.put.members/put_long_double_fr_FR.pass.cpp
@@ -13,9 +13,6 @@
 
 // XFAIL: LIBCXX-WINDOWS-FIXME
 
-// TODO(mordante): Investigate these localization/format failures since updating the Docker image in CI
-// UNSUPPORTED: stdlib=libc++
-
 // REQUIRES: locale.fr_FR.UTF-8
 
 // <locale>
diff --git a/libcxx/test/std/localization/locale.categories/category.monetary/locale.moneypunct.byname/thousands_sep.pass.cpp b/libcxx/test/std/localization/locale.categories/category.monetary/locale.moneypunct.byname/thousands_sep.pass.cpp
--- a/libcxx/test/std/localization/locale.categories/category.monetary/locale.moneypunct.byname/thousands_sep.pass.cpp
+++ b/libcxx/test/std/localization/locale.categories/category.monetary/locale.moneypunct.byname/thousands_sep.pass.cpp
@@ -11,9 +11,6 @@
 
 // XFAIL: LIBCXX-WINDOWS-FIXME
 
-// TODO(mordante): Investigate these localization/format failures since updating the Docker image in CI
-// UNSUPPORTED: stdlib=libc++
-
 // REQUIRES: locale.en_US.UTF-8
 // REQUIRES: locale.fr_FR.UTF-8
 // REQUIRES: locale.ru_RU.UTF-8
diff --git a/libcxx/test/std/localization/locale.categories/facet.numpunct/locale.numpunct.byname/thousands_sep.pass.cpp b/libcxx/test/std/localization/locale.categories/facet.numpunct/locale.numpunct.byname/thousands_sep.pass.cpp
--- a/libcxx/test/std/localization/locale.categories/facet.numpunct/locale.numpunct.byname/thousands_sep.pass.cpp
+++ b/libcxx/test/std/localization/locale.categories/facet.numpunct/locale.numpunct.byname/thousands_sep.pass.cpp
@@ -11,9 +11,6 @@
 
 // XFAIL: LIBCXX-WINDOWS-FIXME
 
-// TODO(mordante): Investigate these localization/format failures since updating the Docker image in CI
-// UNSUPPORTED: stdlib=libc++
-
 // REQUIRES: locale.en_US.UTF-8
 // REQUIRES: locale.fr_FR.UTF-8