Index: libcxx/include/cmath
===================================================================
--- libcxx/include/cmath
+++ libcxx/include/cmath
@@ -335,9 +335,7 @@
 using ::float_t;
 using ::double_t;
 
-#ifndef _AIX
 using ::abs;
-#endif
 
 using ::acos;
 using ::acosf;
Index: libcxx/include/stdlib.h
===================================================================
--- libcxx/include/stdlib.h
+++ libcxx/include/stdlib.h
@@ -103,18 +103,22 @@
 #endif
 
 // MSVCRT already has the correct prototype in <stdlib.h> if __cplusplus is defined
-#if !defined(_LIBCPP_MSVCRT) && !defined(__sun__) && !defined(_AIX)
+#if !defined(_LIBCPP_MSVCRT) && !defined(__sun__)
+#if !defined(_AIX) || (!defined(__ibmxl__) && !defined(__IBMCPP__)) ||         \
+    !defined(__ABS_LONG__)
 inline _LIBCPP_INLINE_VISIBILITY long abs(long __x) _NOEXCEPT {
   return __builtin_labs(__x);
 }
+#endif // _AIX
 #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)
+#endif // !defined(_LIBCPP_MSVCRT) && !defined(__sun__)
 
-#if !(defined(_AIX) || defined(__sun__))
+#if !defined(__sun__)
+#if !defined(_AIX) || (!defined(__ibmxl__) && !defined(__IBMCPP__))
 inline _LIBCPP_INLINE_VISIBILITY float abs(float __lcpp_x) _NOEXCEPT {
   return __builtin_fabsf(__lcpp_x); // Use builtins to prevent needing math.h
 }
@@ -127,7 +131,8 @@
 abs(long double __lcpp_x) _NOEXCEPT {
   return __builtin_fabsl(__lcpp_x);
 }
-#endif // !(defined(_AIX) || defined(__sun__))
+#endif // _AIX
+#endif // !defined(__sun__)
 
 // div
 
@@ -138,7 +143,8 @@
 #endif
 
 // MSVCRT already has the correct prototype in <stdlib.h> if __cplusplus is defined
-#if !defined(_LIBCPP_MSVCRT) && !defined(__sun__) && !defined(_AIX)
+#if !defined(_LIBCPP_MSVCRT) && !defined(__sun__)
+#if !defined(_AIX) || (!defined(__ibmxl__) && !defined(__IBMCPP__))
 inline _LIBCPP_INLINE_VISIBILITY ldiv_t div(long __x, long __y) _NOEXCEPT {
   return ::ldiv(__x, __y);
 }
@@ -148,7 +154,8 @@
   return ::lldiv(__x, __y);
 }
 #endif // _LIBCPP_HAS_NO_LONG_LONG
-#endif // _LIBCPP_MSVCRT / __sun__ / _AIX
+#endif // _AIX
+#endif // _LIBCPP_MSVCRT / __sun__
 } // extern "C++"
 #endif  // __cplusplus