diff --git a/include/cctype b/include/cctype
index db163434b..a68c2a066 100644
--- a/include/cctype
+++ b/include/cctype
@@ -37,10 +37,6 @@ int toupper(int c);
 
 #include <__config>
 #include <ctype.h>
-#if defined(_LIBCPP_MSVCRT)
-#include "support/win32/support.h"
-#include "support/win32/locale_win32.h"
-#endif // _LIBCPP_MSVCRT
 
 #if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER)
 #pragma GCC system_header
@@ -48,33 +44,19 @@ int toupper(int c);
 
 _LIBCPP_BEGIN_NAMESPACE_STD
 
-#undef isalnum
 using ::isalnum;
-#undef isalpha
 using ::isalpha;
-#undef isblank
 using ::isblank;
-#undef iscntrl
 using ::iscntrl;
-#undef isdigit
 using ::isdigit;
-#undef isgraph
 using ::isgraph;
-#undef islower
 using ::islower;
-#undef isprint
 using ::isprint;
-#undef ispunct
 using ::ispunct;
-#undef isspace
 using ::isspace;
-#undef isupper
 using ::isupper;
-#undef isxdigit
 using ::isxdigit;
-#undef tolower
 using ::tolower;
-#undef toupper
 using ::toupper;
 
 _LIBCPP_END_NAMESPACE_STD
diff --git a/include/ctype.h b/include/ctype.h
new file mode 100644
index 000000000..63f0b2960
--- /dev/null
+++ b/include/ctype.h
@@ -0,0 +1,68 @@
+// -*- C++ -*-
+//===---------------------------- ctype.h ---------------------------------===//
+//
+//                     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.
+//
+//===----------------------------------------------------------------------===//
+
+#ifndef _LIBCPP_CTYPE_H
+#define _LIBCPP_CTYPE_H
+
+/*
+    ctype.h synopsis
+
+int isalnum(int c);
+int isalpha(int c);
+int isblank(int c);  // C99
+int iscntrl(int c);
+int isdigit(int c);
+int isgraph(int c);
+int islower(int c);
+int isprint(int c);
+int ispunct(int c);
+int isspace(int c);
+int isupper(int c);
+int isxdigit(int c);
+int tolower(int c);
+int toupper(int c);
+*/
+
+#include <__config>
+#include_next <ctype.h>
+
+#if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER)
+#pragma GCC system_header
+#endif
+
+#ifdef __cplusplus
+
+#if defined(_LIBCPP_MSVCRT)
+// We support including .h headers inside 'extern "C"' contexts, so switch
+// back to C++ linkage before including these C++ headers.
+extern "C++" {
+  #include "support/win32/support.h"
+  #include "support/win32/locale_win32.h"
+}
+#endif // _LIBCPP_MSVCRT
+
+#undef isalnum
+#undef isalpha
+#undef isblank
+#undef iscntrl
+#undef isdigit
+#undef isgraph
+#undef islower
+#undef isprint
+#undef ispunct
+#undef isspace
+#undef isupper
+#undef isxdigit
+#undef tolower
+#undef toupper
+
+#endif
+
+#endif  // _LIBCPP_CTYPE_H
diff --git a/test/std/strings/c.strings/cctype.pass.cpp b/test/std/strings/c.strings/cctype.pass.cpp
index 867338fb0..027fbcd46 100644
--- a/test/std/strings/c.strings/cctype.pass.cpp
+++ b/test/std/strings/c.strings/cctype.pass.cpp
@@ -86,18 +86,18 @@ int main()
     static_assert((std::is_same<decltype(std::tolower(0)), int>::value), "");
     static_assert((std::is_same<decltype(std::toupper(0)), int>::value), "");
 
-    assert(isalnum('a'));
-    assert(isalpha('a'));
-    assert(isblank(' '));
-    assert(!iscntrl(' '));
-    assert(!isdigit('a'));
-    assert(isgraph('a'));
-    assert(islower('a'));
-    assert(isprint('a'));
-    assert(!ispunct('a'));
-    assert(!isspace('a'));
-    assert(!isupper('a'));
-    assert(isxdigit('a'));
-    assert(tolower('A') == 'a');
-    assert(toupper('a') == 'A');
+    assert(std::isalnum('a'));
+    assert(std::isalpha('a'));
+    assert(std::isblank(' '));
+    assert(!std::iscntrl(' '));
+    assert(!std::isdigit('a'));
+    assert(std::isgraph('a'));
+    assert(std::islower('a'));
+    assert(std::isprint('a'));
+    assert(!std::ispunct('a'));
+    assert(!std::isspace('a'));
+    assert(!std::isupper('a'));
+    assert(std::isxdigit('a'));
+    assert(std::tolower('A') == 'a');
+    assert(std::toupper('a') == 'A');
 }