diff --git a/libcxx/test/std/re/re.alg/re.alg.match/basic.locale.pass.cpp b/libcxx/test/std/re/re.alg/re.alg.match/basic.locale.pass.cpp
--- a/libcxx/test/std/re/re.alg/re.alg.match/basic.locale.pass.cpp
+++ b/libcxx/test/std/re/re.alg/re.alg.match/basic.locale.pass.cpp
@@ -8,7 +8,6 @@
 //
 // NetBSD does not support LC_COLLATE at the moment
 // XFAIL: netbsd
-// XFAIL: LIBCXX-AIX-FIXME
 
 // REQUIRES: locale.cs_CZ.ISO8859-2
 
@@ -37,8 +36,15 @@
     {
         std::cmatch m;
         const char s[] = "m";
+// AIX supports character equivalence classes. What the contents of the class are depends
+// on the locale and the standards do not specify any locale other than C/POSIX.
+#if defined(_AIX)
+        assert(std::regex_match(s, m, std::regex("[a[=m=]z]",
+                                                 std::regex_constants::basic)));
+#else
         assert(std::regex_match(s, m, std::regex("[a[=M=]z]",
                                                  std::regex_constants::basic)));
+#endif
         assert(m.size() == 1);
         assert(!m.prefix().matched);
         assert(m.prefix().first == s);
@@ -80,8 +86,13 @@
     {
         std::wcmatch m;
         const wchar_t s[] = L"m";
+#if defined(_AIX)
+        assert(std::regex_match(s, m, std::wregex(L"[a[=m=]z]",
+                                                 std::regex_constants::basic)));
+#else
         assert(std::regex_match(s, m, std::wregex(L"[a[=M=]z]",
                                                  std::regex_constants::basic)));
+#endif
         assert(m.size() == 1);
         assert(!m.prefix().matched);
         assert(m.prefix().first == s);
@@ -93,6 +104,8 @@
         assert(m.position(0) == 0);
         assert(m.str(0) == s);
     }
+//TODO: Need to be investigated for AIX OS
+#if !defined(_AIX)
     {
         std::wcmatch m;
         const wchar_t s[] = L"Ch";
@@ -109,6 +122,7 @@
         assert(m.position(0) == 0);
         assert(m.str(0) == s);
     }
+#endif
     std::locale::global(std::locale("C"));
     {
         std::wcmatch m;
diff --git a/libcxx/test/std/re/re.alg/re.alg.match/ecma.locale.pass.cpp b/libcxx/test/std/re/re.alg/re.alg.match/ecma.locale.pass.cpp
--- a/libcxx/test/std/re/re.alg/re.alg.match/ecma.locale.pass.cpp
+++ b/libcxx/test/std/re/re.alg/re.alg.match/ecma.locale.pass.cpp
@@ -8,7 +8,6 @@
 //
 // NetBSD does not support LC_COLLATE at the moment
 // XFAIL: netbsd
-// XFAIL: LIBCXX-AIX-FIXME
 
 // REQUIRES: locale.cs_CZ.ISO8859-2
 
@@ -37,7 +36,13 @@
     {
         std::cmatch m;
         const char s[] = "m";
+// AIX supports character equivalence classes. What the contents of the class are depends
+// on the locale and the standards do not specify any locale other than C/POSIX.
+#if defined(_AIX)
+        assert(std::regex_match(s, m, std::regex("[a[=m=]z]")));
+#else
         assert(std::regex_match(s, m, std::regex("[a[=M=]z]")));
+#endif
         assert(m.size() == 1);
         assert(!m.prefix().matched);
         assert(m.prefix().first == s);
@@ -78,7 +83,11 @@
     {
         std::wcmatch m;
         const wchar_t s[] = L"m";
+#if defined(_AIX)
+        assert(std::regex_match(s, m, std::wregex(L"[a[=m=]z]")));
+#else
         assert(std::regex_match(s, m, std::wregex(L"[a[=M=]z]")));
+#endif
         assert(m.size() == 1);
         assert(!m.prefix().matched);
         assert(m.prefix().first == s);
@@ -90,6 +99,8 @@
         assert(m.position(0) == 0);
         assert(m.str(0) == s);
     }
+//TODO: Need to be investigated for AIX OS
+#if !defined(_AIX)
     {
         std::wcmatch m;
         const wchar_t s[] = L"Ch";
@@ -106,6 +117,7 @@
         assert(m.position(0) == 0);
         assert(m.str(0) == s);
     }
+#endif
     std::locale::global(std::locale("C"));
     {
         std::wcmatch m;
diff --git a/libcxx/test/std/re/re.alg/re.alg.match/extended.locale.pass.cpp b/libcxx/test/std/re/re.alg/re.alg.match/extended.locale.pass.cpp
--- a/libcxx/test/std/re/re.alg/re.alg.match/extended.locale.pass.cpp
+++ b/libcxx/test/std/re/re.alg/re.alg.match/extended.locale.pass.cpp
@@ -8,7 +8,6 @@
 //
 // NetBSD does not support LC_COLLATE at the moment
 // XFAIL: netbsd
-// XFAIL: LIBCXX-AIX-FIXME
 
 // REQUIRES: locale.cs_CZ.ISO8859-2
 
@@ -37,8 +36,15 @@
     {
         std::cmatch m;
         const char s[] = "m";
+// AIX supports character equivalence classes. What the contents of the class are depends
+// on the locale and the standards do not specify any locale other than C/POSIX.
+#if defined(_AIX)
+        assert(std::regex_match(s, m, std::regex("[a[=m=]z]",
+                                                 std::regex_constants::extended)));
+#else
         assert(std::regex_match(s, m, std::regex("[a[=M=]z]",
                                                  std::regex_constants::extended)));
+#endif
         assert(m.size() == 1);
         assert(!m.prefix().matched);
         assert(m.prefix().first == s);
@@ -80,8 +86,13 @@
     {
         std::wcmatch m;
         const wchar_t s[] = L"m";
+#if defined(_AIX)
+        assert(std::regex_match(s, m, std::wregex(L"[a[=m=]z]",
+                                                 std::regex_constants::extended)));
+#else
         assert(std::regex_match(s, m, std::wregex(L"[a[=M=]z]",
                                                  std::regex_constants::extended)));
+#endif
         assert(m.size() == 1);
         assert(!m.prefix().matched);
         assert(m.prefix().first == s);
@@ -93,6 +104,8 @@
         assert(m.position(0) == 0);
         assert(m.str(0) == s);
     }
+//TODO: Need to be investigated for AIX OS
+#if !defined(_AIX)
     {
         std::wcmatch m;
         const wchar_t s[] = L"Ch";
@@ -109,6 +122,7 @@
         assert(m.position(0) == 0);
         assert(m.str(0) == s);
     }
+#endif
     std::locale::global(std::locale("C"));
     {
         std::wcmatch m;
diff --git a/libcxx/test/std/re/re.alg/re.alg.search/awk.locale.pass.cpp b/libcxx/test/std/re/re.alg/re.alg.search/awk.locale.pass.cpp
--- a/libcxx/test/std/re/re.alg/re.alg.search/awk.locale.pass.cpp
+++ b/libcxx/test/std/re/re.alg/re.alg.search/awk.locale.pass.cpp
@@ -8,7 +8,6 @@
 //
 // NetBSD does not support LC_COLLATE at the moment
 // XFAIL: netbsd
-// XFAIL: LIBCXX-AIX-FIXME
 
 // REQUIRES: locale.cs_CZ.ISO8859-2
 
@@ -37,8 +36,15 @@
     {
         std::cmatch m;
         const char s[] = "m";
+// AIX supports character equivalence classes. What the contents of the class are depends
+// on the locale and the standards do not specify any locale other than C/POSIX.
+#if defined(_AIX)
+        assert(std::regex_search(s, m, std::regex("[a[=m=]z]",
+                                                 std::regex_constants::awk)));
+#else
         assert(std::regex_search(s, m, std::regex("[a[=M=]z]",
                                                  std::regex_constants::awk)));
+#endif
         assert(m.size() == 1);
         assert(!m.prefix().matched);
         assert(m.prefix().first == s);
@@ -80,8 +86,13 @@
     {
         std::wcmatch m;
         const wchar_t s[] = L"m";
+#if defined(_AIX)
+        assert(std::regex_search(s, m, std::wregex(L"[a[=m=]z]",
+                                                 std::regex_constants::awk)));
+#else
         assert(std::regex_search(s, m, std::wregex(L"[a[=M=]z]",
                                                  std::regex_constants::awk)));
+#endif
         assert(m.size() == 1);
         assert(!m.prefix().matched);
         assert(m.prefix().first == s);
@@ -93,6 +104,8 @@
         assert(m.position(0) == 0);
         assert(m.str(0) == s);
     }
+//TODO: Need to be investigated for AIX OS
+#if !defined(_AIX)
     {
         std::wcmatch m;
         const wchar_t s[] = L"Ch";
@@ -109,6 +122,7 @@
         assert(m.position(0) == 0);
         assert(m.str(0) == s);
     }
+#endif
     std::locale::global(std::locale("C"));
     {
         std::wcmatch m;
diff --git a/libcxx/test/std/re/re.alg/re.alg.search/basic.locale.pass.cpp b/libcxx/test/std/re/re.alg/re.alg.search/basic.locale.pass.cpp
--- a/libcxx/test/std/re/re.alg/re.alg.search/basic.locale.pass.cpp
+++ b/libcxx/test/std/re/re.alg/re.alg.search/basic.locale.pass.cpp
@@ -8,7 +8,6 @@
 //
 // NetBSD does not support LC_COLLATE at the moment
 // XFAIL: netbsd
-// XFAIL: LIBCXX-AIX-FIXME
 
 // REQUIRES: locale.cs_CZ.ISO8859-2
 
@@ -37,8 +36,15 @@
     {
         std::cmatch m;
         const char s[] = "m";
+// AIX supports character equivalence classes. What the contents of the class are depends
+// on the locale and the standards do not specify any locale other than C/POSIX.
+#if defined(_AIX)
+        assert(std::regex_search(s, m, std::regex("[a[=m=]z]",
+                                                 std::regex_constants::basic)));
+#else
         assert(std::regex_search(s, m, std::regex("[a[=M=]z]",
                                                  std::regex_constants::basic)));
+#endif
         assert(m.size() == 1);
         assert(!m.prefix().matched);
         assert(m.prefix().first == s);
@@ -80,8 +86,13 @@
     {
         std::wcmatch m;
         const wchar_t s[] = L"m";
+#if defined(_AIX)
+        assert(std::regex_search(s, m, std::wregex(L"[a[=m=]z]",
+                                                 std::regex_constants::basic)));
+#else
         assert(std::regex_search(s, m, std::wregex(L"[a[=M=]z]",
                                                  std::regex_constants::basic)));
+#endif
         assert(m.size() == 1);
         assert(!m.prefix().matched);
         assert(m.prefix().first == s);
@@ -93,6 +104,8 @@
         assert(m.position(0) == 0);
         assert(m.str(0) == s);
     }
+//TODO: Need to be investigated for AIX OS
+#if !defined(_AIX)
     {
         std::wcmatch m;
         const wchar_t s[] = L"Ch";
@@ -109,6 +122,7 @@
         assert(m.position(0) == 0);
         assert(m.str(0) == s);
     }
+#endif
     std::locale::global(std::locale("C"));
     {
         std::wcmatch m;
diff --git a/libcxx/test/std/re/re.alg/re.alg.search/ecma.locale.pass.cpp b/libcxx/test/std/re/re.alg/re.alg.search/ecma.locale.pass.cpp
--- a/libcxx/test/std/re/re.alg/re.alg.search/ecma.locale.pass.cpp
+++ b/libcxx/test/std/re/re.alg/re.alg.search/ecma.locale.pass.cpp
@@ -8,7 +8,6 @@
 //
 // NetBSD does not support LC_COLLATE at the moment
 // XFAIL: netbsd
-// XFAIL: LIBCXX-AIX-FIXME
 
 // REQUIRES: locale.cs_CZ.ISO8859-2
 
@@ -37,7 +36,13 @@
     {
         std::cmatch m;
         const char s[] = "m";
+// AIX supports character equivalence classes. What the contents of the class are depends
+// on the locale and the standards do not specify any locale other than C/POSIX.
+#if defined(_AIX)
+        assert(std::regex_search(s, m, std::regex("[a[=m=]z]")));
+#else
         assert(std::regex_search(s, m, std::regex("[a[=M=]z]")));
+#endif
         assert(m.size() == 1);
         assert(!m.prefix().matched);
         assert(m.prefix().first == s);
@@ -78,7 +83,11 @@
     {
         std::wcmatch m;
         const wchar_t s[] = L"m";
+#if defined(_AIX)
+        assert(std::regex_search(s, m, std::wregex(L"[a[=m=]z]")));
+#else
         assert(std::regex_search(s, m, std::wregex(L"[a[=M=]z]")));
+#endif
         assert(m.size() == 1);
         assert(!m.prefix().matched);
         assert(m.prefix().first == s);
@@ -90,6 +99,8 @@
         assert(m.position(0) == 0);
         assert(m.str(0) == s);
     }
+//TODO: Need to be investigated for AIX OS
+#if !defined(_AIX)
     {
         std::wcmatch m;
         const wchar_t s[] = L"Ch";
@@ -106,6 +117,7 @@
         assert(m.position(0) == 0);
         assert(m.str(0) == s);
     }
+#endif
     std::locale::global(std::locale("C"));
     {
         std::wcmatch m;
diff --git a/libcxx/test/std/re/re.alg/re.alg.search/extended.locale.pass.cpp b/libcxx/test/std/re/re.alg/re.alg.search/extended.locale.pass.cpp
--- a/libcxx/test/std/re/re.alg/re.alg.search/extended.locale.pass.cpp
+++ b/libcxx/test/std/re/re.alg/re.alg.search/extended.locale.pass.cpp
@@ -8,7 +8,6 @@
 //
 // NetBSD does not support LC_COLLATE at the moment
 // XFAIL: netbsd
-// XFAIL: LIBCXX-AIX-FIXME
 
 // REQUIRES: locale.cs_CZ.ISO8859-2
 
@@ -37,8 +36,15 @@
     {
         std::cmatch m;
         const char s[] = "m";
+// AIX supports character equivalence classes. What the contents of the class are depends
+// on the locale and the standards do not specify any locale other than C/POSIX.
+#if defined(_AIX)
+        assert(std::regex_search(s, m, std::regex("[a[=m=]z]",
+                                                 std::regex_constants::extended)));
+#else
         assert(std::regex_search(s, m, std::regex("[a[=M=]z]",
                                                  std::regex_constants::extended)));
+#endif
         assert(m.size() == 1);
         assert(!m.prefix().matched);
         assert(m.prefix().first == s);
@@ -80,8 +86,13 @@
     {
         std::wcmatch m;
         const wchar_t s[] = L"m";
+#if defined(_AIX)
+        assert(std::regex_search(s, m, std::wregex(L"[a[=m=]z]",
+                                                 std::regex_constants::extended)));
+#else
         assert(std::regex_search(s, m, std::wregex(L"[a[=M=]z]",
                                                  std::regex_constants::extended)));
+#endif
         assert(m.size() == 1);
         assert(!m.prefix().matched);
         assert(m.prefix().first == s);
@@ -93,6 +104,8 @@
         assert(m.position(0) == 0);
         assert(m.str(0) == s);
     }
+//TODO: Need to be investigated for AIX OS
+#if !defined(_AIX)
     {
         std::wcmatch m;
         const wchar_t s[] = L"Ch";
@@ -109,6 +122,7 @@
         assert(m.position(0) == 0);
         assert(m.str(0) == s);
     }
+#endif
     std::locale::global(std::locale("C"));
     {
         std::wcmatch m;
diff --git a/libcxx/test/std/re/re.traits/lookup_collatename.pass.cpp b/libcxx/test/std/re/re.traits/lookup_collatename.pass.cpp
--- a/libcxx/test/std/re/re.traits/lookup_collatename.pass.cpp
+++ b/libcxx/test/std/re/re.traits/lookup_collatename.pass.cpp
@@ -8,7 +8,6 @@
 //
 // NetBSD does not support LC_COLLATE at the moment
 // XFAIL: netbsd
-// XFAIL: LIBCXX-AIX-FIXME
 
 // REQUIRES: locale.cs_CZ.ISO8859-2
 
@@ -191,8 +190,13 @@
 
     test(L"tild", std::wstring(L""));
     test(L"ch", std::wstring(L""));
+
+//TODO: Need to be investigated for AIX OS
+#if !defined(_AIX)
     std::locale::global(std::locale(LOCALE_cs_CZ_ISO8859_2));
     test(L"ch", std::wstring(L"ch"));
+#endif
+
     std::locale::global(std::locale("C"));
 #endif // TEST_HAS_NO_WIDE_CHARACTERS