diff --git a/libcxx/test/std/localization/locale.categories/category.collate/locale.collate.byname/compare.pass.cpp b/libcxx/test/std/localization/locale.categories/category.collate/locale.collate.byname/compare.pass.cpp
--- a/libcxx/test/std/localization/locale.categories/category.collate/locale.collate.byname/compare.pass.cpp
+++ b/libcxx/test/std/localization/locale.categories/category.collate/locale.collate.byname/compare.pass.cpp
@@ -19,11 +19,8 @@
 //     has any difference from "C" collation.  But I do believe I'm picking
 //     up the OS's collation files.
 
-// TODO investigation needed.
-// Glibc seems to collate files differently from the way Apple's C library does it.
-// XFAIL: target={{.*}}-linux-gnu{{.*}}
-
-// XFAIL: LIBCXX-WINDOWS-FIXME
+// https://llvm.org/PR41018
+// XFAIL: windows-dll && msvc
 
 // XFAIL: LIBCXX-AIX-FIXME
 
@@ -36,24 +33,49 @@
 #include "test_macros.h"
 #include "platform_support.h" // locale name macros
 
+#define ASSERT_COMPARE(type, str1, str2, expected) \
+    do { \
+        type s1(str1); \
+        type s2(str2); \
+        assert(f.compare(s1.data(), s1.data() + s1.size(), \
+                         s2.data(), s2.data() + s2.size()) == (expected)); \
+    } while (0)
+
 int main(int, char**)
 {
     {
         std::locale l(LOCALE_en_US_UTF_8);
         {
             const std::collate<char>& f = std::use_facet<std::collate<char> >(l);
-            std::string s2("aaaaaaA");
-            std::string s3("BaaaaaA");
-            assert(f.compare(s2.data(), s2.data() + s2.size(),
-                             s3.data(), s3.data() + s3.size()) == 1);
+
+            ASSERT_COMPARE(std::string, "aaa", "bbb", -1);
+            ASSERT_COMPARE(std::string, "AAA", "BBB", -1);
+            ASSERT_COMPARE(std::string, "bbb", "aaa", 1);
+            ASSERT_COMPARE(std::string, "ccc", "ccc", 0);
+
+#if defined(__APPLE__)
+            // Apple's default collation is case-sensitive
+            ASSERT_COMPARE(std::string, "aaaaaaA", "BaaaaaA", 1);
+#else
+            // Glibc, Windows, and FreeBSD's default collation is case-insensitive
+            ASSERT_COMPARE(std::string, "aaaaaaA", "BaaaaaA", -1);
+#endif
         }
 #ifndef TEST_HAS_NO_WIDE_CHARACTERS
         {
             const std::collate<wchar_t>& f = std::use_facet<std::collate<wchar_t> >(l);
-            std::wstring s2(L"aaaaaaA");
-            std::wstring s3(L"BaaaaaA");
-            assert(f.compare(s2.data(), s2.data() + s2.size(),
-                             s3.data(), s3.data() + s3.size()) == 1);
+
+            ASSERT_COMPARE(std::wstring, L"aaa", L"bbb", -1);
+            ASSERT_COMPARE(std::wstring, L"AAA", L"BBB", -1);
+            ASSERT_COMPARE(std::wstring, L"bbb", L"aaa", 1);
+            ASSERT_COMPARE(std::wstring, L"ccc", L"ccc", 0);
+#if defined(__APPLE__)
+            // Apple's default collation is case-sensitive
+            ASSERT_COMPARE(std::wstring, L"aaaaaaA", L"BaaaaaA", 1);
+#else
+            // Glibc, Windows, and FreeBSD's default collation is case-insensitive
+            ASSERT_COMPARE(std::wstring, L"aaaaaaA", L"BaaaaaA", -1);
+#endif
         }
 #endif
     }
@@ -61,18 +83,25 @@
         std::locale l("C");
         {
             const std::collate<char>& f = std::use_facet<std::collate<char> >(l);
-            std::string s2("aaaaaaA");
-            std::string s3("BaaaaaA");
-            assert(f.compare(s2.data(), s2.data() + s2.size(),
-                             s3.data(), s3.data() + s3.size()) == 1);
+            ASSERT_COMPARE(std::string, "aaa", "bbb", -1);
+            ASSERT_COMPARE(std::string, "AAA", "BBB", -1);
+            ASSERT_COMPARE(std::string, "bbb", "aaa", 1);
+            ASSERT_COMPARE(std::string, "ccc", "ccc", 0);
+
+            // In the C locale, these are collated lexicographically.
+            ASSERT_COMPARE(std::string, "aaaaaaA", "BaaaaaA", 1);
         }
 #ifndef TEST_HAS_NO_WIDE_CHARACTERS
         {
             const std::collate<wchar_t>& f = std::use_facet<std::collate<wchar_t> >(l);
-            std::wstring s2(L"aaaaaaA");
-            std::wstring s3(L"BaaaaaA");
-            assert(f.compare(s2.data(), s2.data() + s2.size(),
-                             s3.data(), s3.data() + s3.size()) == 1);
+
+            ASSERT_COMPARE(std::wstring, L"aaa", L"bbb", -1);
+            ASSERT_COMPARE(std::wstring, L"AAA", L"BBB", -1);
+            ASSERT_COMPARE(std::wstring, L"bbb", L"aaa", 1);
+            ASSERT_COMPARE(std::wstring, L"ccc", L"ccc", 0);
+
+            // In the C locale, these are collated lexicographically.
+            ASSERT_COMPARE(std::wstring, L"aaaaaaA", L"BaaaaaA", 1);
         }
 #endif
     }