Index: libcxx/include/regex
===================================================================
--- libcxx/include/regex
+++ libcxx/include/regex
@@ -2427,7 +2427,6 @@
           const bool __in_neg_mask = (__neg_mask_ == 0) ||
               __traits_.isctype(__ch, __neg_mask_);
           const bool __in_neg_chars =
-              __neg_chars_.empty() ||
               std::find(__neg_chars_.begin(), __neg_chars_.end(), __ch) !=
               __neg_chars_.end();
           if (!(__in_neg_mask || __in_neg_chars))
Index: libcxx/test/std/re/re.alg/re.alg.match/inverted_character_classes.pass.cpp
===================================================================
--- /dev/null
+++ libcxx/test/std/re/re.alg/re.alg.match/inverted_character_classes.pass.cpp
@@ -0,0 +1,29 @@
+//===----------------------------------------------------------------------===//
+//
+//                     The LLVM Compiler Infrastructure
+//
+// This file is dual licensed under the MIT and the University of Illinois Open
+// Source Licenses. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+
+// <regex>
+// UNSUPPORTED: c++98, c++03
+
+// Make sure that we correctly match inverted character classes.
+
+#include <cassert>
+#include <regex>
+
+
+int main() {
+    assert(std::regex_match("X", std::regex("[\\S]")));
+    assert(!std::regex_match("X", std::regex("[^\\S]")));
+
+    assert(!std::regex_match("X", std::regex("[\\s]")));
+    assert(std::regex_match("X", std::regex("[^\\s]")));
+
+    assert(std::regex_match("X", std::regex("[\\s\\S]")));
+    assert(std::regex_match("X", std::regex("[^Y\\s]")));
+    assert(!std::regex_match("X", std::regex("[^X\\s]")));
+}