diff --git a/libcxx/include/math.h b/libcxx/include/math.h
index 1603d5748e2d4d..c9b4733e9c446c 100644
--- a/libcxx/include/math.h
+++ b/libcxx/include/math.h
@@ -297,6 +297,9 @@ long double    truncl(long double x);
 #pragma GCC system_header
 #endif
 
+#define _LIBCPP_STDLIB_INCLUDE_NEXT
+#include <stdlib.h>
+
 #include_next <math.h>
 
 #ifdef __cplusplus
@@ -305,7 +308,6 @@ long double    truncl(long double x);
 // back to C++ linkage before including these C++ headers.
 extern "C++" {
 
-#include <stdlib.h>
 #include <type_traits>
 #include <limits>
 
@@ -758,12 +760,61 @@ isunordered(_A1 __lcpp_x, _A2 __lcpp_y) _NOEXCEPT
 #endif  // isunordered
 
 // abs
-//
-// handled in stdlib.h
+
+#undef abs
+#undef labs
+#ifndef _LIBCPP_HAS_NO_LONG_LONG
+#undef llabs
+#endif
+
+// MSVCRT already has the correct prototype in <stdlib.h> if __cplusplus is defined
+#if !defined(_LIBCPP_MSVCRT) && !defined(__sun__) && !defined(_AIX)
+inline _LIBCPP_INLINE_VISIBILITY long abs(long __x) _NOEXCEPT {
+  return ::labs(__x);
+}
+#ifndef _LIBCPP_HAS_NO_LONG_LONG
+inline _LIBCPP_INLINE_VISIBILITY long long abs(long long __x) _NOEXCEPT {
+  return ::llabs(__x);
+}
+#endif // _LIBCPP_HAS_NO_LONG_LONG
+#endif // !defined(_LIBCPP_MSVCRT) && !defined(__sun__) && !defined(_AIX)
+
+
+#if !(defined(_AIX) || defined(__sun__))
+inline _LIBCPP_INLINE_VISIBILITY float abs(float __lcpp_x) _NOEXCEPT {
+  return ::fabsf(__lcpp_x);
+}
+
+inline _LIBCPP_INLINE_VISIBILITY double abs(double __lcpp_x) _NOEXCEPT {
+  return ::fabs(__lcpp_x);
+}
+
+inline _LIBCPP_INLINE_VISIBILITY long double
+abs(long double __lcpp_x) _NOEXCEPT {
+  return ::fabsl(__lcpp_x);
+}
+#endif // !(defined(_AIX) || defined(__sun__))
 
 // div
-//
-// handled in stdlib.h
+
+#undef div
+#undef ldiv
+#ifndef _LIBCPP_HAS_NO_LONG_LONG
+#undef lldiv
+#endif
+
+// MSVCRT already has the correct prototype in <stdlib.h> if __cplusplus is defined
+#if !defined(_LIBCPP_MSVCRT) && !defined(__sun__) && !defined(_AIX)
+inline _LIBCPP_INLINE_VISIBILITY ldiv_t div(long __x, long __y) _NOEXCEPT {
+  return ::ldiv(__x, __y);
+}
+#ifndef _LIBCPP_HAS_NO_LONG_LONG
+inline _LIBCPP_INLINE_VISIBILITY lldiv_t div(long long __x,
+                                             long long __y) _NOEXCEPT {
+  return ::lldiv(__x, __y);
+}
+#endif // _LIBCPP_HAS_NO_LONG_LONG
+#endif // _LIBCPP_MSVCRT / __sun__ / _AIX
 
 // acos
 
diff --git a/libcxx/include/stdlib.h b/libcxx/include/stdlib.h
index 812ea1024edf87..1d6827587037ce 100644
--- a/libcxx/include/stdlib.h
+++ b/libcxx/include/stdlib.h
@@ -7,12 +7,16 @@
 //
 //===----------------------------------------------------------------------===//
 
-#if defined(__need_malloc_and_calloc)
+#if defined(__need_malloc_and_calloc) || defined(_LIBCPP_STDLIB_INCLUDE_NEXT)
 
 #if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER)
 #pragma GCC system_header
 #endif
 
+#if defined(_LIBCPP_STDLIB_INCLUDE_NEXT)
+#undef _LIBCPP_STDLIB_INCLUDE_NEXT
+#endif
+
 #include_next <stdlib.h>
 
 #elif !defined(_LIBCPP_STDLIB_H)
@@ -93,63 +97,7 @@ void *aligned_alloc(size_t alignment, size_t size);                       // C11
 #include_next <stdlib.h>
 
 #ifdef __cplusplus
-extern "C++" {
-// abs
-
-#undef abs
-#undef labs
-#ifndef _LIBCPP_HAS_NO_LONG_LONG
-#undef llabs
-#endif
-
-// MSVCRT already has the correct prototype in <stdlib.h> if __cplusplus is defined
-#if !defined(_LIBCPP_MSVCRT) && !defined(__sun__) && !defined(_AIX)
-inline _LIBCPP_INLINE_VISIBILITY long abs(long __x) _NOEXCEPT {
-  return __builtin_labs(__x);
-}
-#ifndef _LIBCPP_HAS_NO_LONG_LONG
-inline _LIBCPP_INLINE_VISIBILITY long long abs(long long __x) _NOEXCEPT {
-  return __builtin_llabs(__x);
-}
-#endif // _LIBCPP_HAS_NO_LONG_LONG
-#endif // !defined(_LIBCPP_MSVCRT) && !defined(__sun__) && !defined(_AIX)
-
-#if !(defined(_AIX) || defined(__sun__))
-inline _LIBCPP_INLINE_VISIBILITY float abs(float __lcpp_x) _NOEXCEPT {
-  return __builtin_fabsf(__lcpp_x); // Use builtins to prevent needing math.h
-}
-
-inline _LIBCPP_INLINE_VISIBILITY double abs(double __lcpp_x) _NOEXCEPT {
-  return __builtin_fabs(__lcpp_x);
-}
-
-inline _LIBCPP_INLINE_VISIBILITY long double
-abs(long double __lcpp_x) _NOEXCEPT {
-  return __builtin_fabsl(__lcpp_x);
-}
-#endif // !(defined(_AIX) || defined(__sun__))
-
-// div
-
-#undef div
-#undef ldiv
-#ifndef _LIBCPP_HAS_NO_LONG_LONG
-#undef lldiv
-#endif
-
-// MSVCRT already has the correct prototype in <stdlib.h> if __cplusplus is defined
-#if !defined(_LIBCPP_MSVCRT) && !defined(__sun__) && !defined(_AIX)
-inline _LIBCPP_INLINE_VISIBILITY ldiv_t div(long __x, long __y) _NOEXCEPT {
-  return ::ldiv(__x, __y);
-}
-#ifndef _LIBCPP_HAS_NO_LONG_LONG
-inline _LIBCPP_INLINE_VISIBILITY lldiv_t div(long long __x,
-                                             long long __y) _NOEXCEPT {
-  return ::lldiv(__x, __y);
-}
-#endif // _LIBCPP_HAS_NO_LONG_LONG
-#endif // _LIBCPP_MSVCRT / __sun__ / _AIX
-} // extern "C++"
+#include <math.h>
 #endif  // __cplusplus
 
 #endif  // _LIBCPP_STDLIB_H