diff --git a/libcxx/include/math.h b/libcxx/include/math.h
--- a/libcxx/include/math.h
+++ b/libcxx/include/math.h
@@ -318,11 +318,7 @@
 
 template <class _A1>
 _LIBCPP_HIDE_FROM_ABI bool __libcpp_signbit(_A1 __x) _NOEXCEPT {
-#      if __has_builtin(__builtin_signbit)
   return __builtin_signbit(__x);
-#      else
-  return signbit(__x);
-#      endif
 }
 
 #      undef signbit
@@ -377,11 +373,7 @@
 
 template <class _A1>
 _LIBCPP_HIDE_FROM_ABI int __libcpp_fpclassify(_A1 __x) _NOEXCEPT {
-#      if __has_builtin(__builtin_fpclassify)
   return __builtin_fpclassify(FP_NAN, FP_INFINITE, FP_NORMAL, FP_SUBNORMAL, FP_ZERO, __x);
-#      else
-  return fpclassify(__x);
-#      endif
 }
 
 #      undef fpclassify
@@ -420,11 +412,7 @@
 
 template <class _A1>
 _LIBCPP_HIDE_FROM_ABI bool __libcpp_isfinite(_A1 __x) _NOEXCEPT {
-#      if __has_builtin(__builtin_isfinite)
   return __builtin_isfinite(__x);
-#      else
-  return isfinite(__x);
-#      endif
 }
 
 #      undef isfinite
@@ -451,11 +439,7 @@
 
 template <class _A1>
 _LIBCPP_HIDE_FROM_ABI bool __libcpp_isinf(_A1 __x) _NOEXCEPT {
-#      if __has_builtin(__builtin_isinf)
   return __builtin_isinf(__x);
-#      else
-  return isinf(__x);
-#      endif
 }
 
 #      undef isinf
@@ -490,11 +474,7 @@
 
 template <class _A1>
 _LIBCPP_HIDE_FROM_ABI bool __libcpp_isnan(_A1 __x) _NOEXCEPT {
-#      if __has_builtin(__builtin_isnan)
   return __builtin_isnan(__x);
-#      else
-  return isnan(__x);
-#      endif
 }
 
 #      undef isnan
@@ -526,11 +506,7 @@
 
 template <class _A1>
 _LIBCPP_HIDE_FROM_ABI bool __libcpp_isnormal(_A1 __x) _NOEXCEPT {
-#      if __has_builtin(__builtin_isnormal)
   return __builtin_isnormal(__x);
-#      else
-  return isnormal(__x);
-#      endif
 }
 
 #      undef isnormal
@@ -1017,43 +993,23 @@
 
 // copysign
 
-#if __has_builtin(__builtin_copysignf)
 _LIBCPP_CONSTEXPR
-#endif
 inline _LIBCPP_HIDE_FROM_ABI float __libcpp_copysign(float __x, float __y) _NOEXCEPT {
-#if __has_builtin(__builtin_copysignf)
   return __builtin_copysignf(__x, __y);
-#else
-  return ::copysignf(__x, __y);
-#endif
 }
 
-#if __has_builtin(__builtin_copysign)
 _LIBCPP_CONSTEXPR
-#endif
 inline _LIBCPP_HIDE_FROM_ABI double __libcpp_copysign(double __x, double __y) _NOEXCEPT {
-#if __has_builtin(__builtin_copysign)
   return __builtin_copysign(__x, __y);
-#else
-  return ::copysign(__x, __y);
-#endif
 }
 
-#if __has_builtin(__builtin_copysignl)
 _LIBCPP_CONSTEXPR
-#endif
 inline _LIBCPP_HIDE_FROM_ABI long double __libcpp_copysign(long double __x, long double __y) _NOEXCEPT {
-#if __has_builtin(__builtin_copysignl)
   return __builtin_copysignl(__x, __y);
-#else
-  return ::copysignl(__x, __y);
-#endif
 }
 
 template <class _A1, class _A2>
-#if __has_builtin(__builtin_copysign)
 _LIBCPP_CONSTEXPR
-#endif
 inline _LIBCPP_HIDE_FROM_ABI
 typename std::__enable_if_t
 <
@@ -1065,11 +1021,7 @@
     typedef typename std::__promote<_A1, _A2>::type __result_type;
     static_assert((!(std::_IsSame<_A1, __result_type>::value &&
                      std::_IsSame<_A2, __result_type>::value)), "");
-#if __has_builtin(__builtin_copysign)
     return __builtin_copysign((__result_type)__x, (__result_type)__y);
-#else
-    return ::copysign((__result_type)__x, (__result_type)__y);
-#endif
 }
 
 inline _LIBCPP_HIDE_FROM_ABI float copysign(float __x, float __y) _NOEXCEPT {
@@ -1157,19 +1109,11 @@
 
 inline _LIBCPP_HIDE_FROM_ABI float       fma(float __x, float __y, float __z) _NOEXCEPT
 {
-#if __has_builtin(__builtin_fmaf)
     return __builtin_fmaf(__x, __y, __z);
-#else
-    return ::fmaf(__x, __y, __z);
-#endif
 }
 inline _LIBCPP_HIDE_FROM_ABI long double fma(long double __x, long double __y, long double __z) _NOEXCEPT
 {
-#if __has_builtin(__builtin_fmal)
     return __builtin_fmal(__x, __y, __z);
-#else
-    return ::fmal(__x, __y, __z);
-#endif
 }
 
 template <class _A1, class _A2, class _A3>
@@ -1187,11 +1131,7 @@
     static_assert((!(std::_IsSame<_A1, __result_type>::value &&
                      std::_IsSame<_A2, __result_type>::value &&
                      std::_IsSame<_A3, __result_type>::value)), "");
-#if __has_builtin(__builtin_fma)
     return __builtin_fma((__result_type)__x, (__result_type)__y, (__result_type)__z);
-#else
-    return ::fma((__result_type)__x, (__result_type)__y, (__result_type)__z);
-#endif
 }
 
 // fmax
@@ -1281,19 +1221,11 @@
 
 inline _LIBCPP_HIDE_FROM_ABI long long llrint(float __x) _NOEXCEPT
 {
-#if __has_builtin(__builtin_llrintf)
     return __builtin_llrintf(__x);
-#else
-    return ::llrintf(__x);
-#endif
 }
 inline _LIBCPP_HIDE_FROM_ABI long long llrint(long double __x) _NOEXCEPT
 {
-#if __has_builtin(__builtin_llrintl)
     return __builtin_llrintl(__x);
-#else
-    return ::llrintl(__x);
-#endif
 }
 
 template <class _A1>
@@ -1301,30 +1233,18 @@
 typename std::enable_if<std::is_integral<_A1>::value, long long>::type
 llrint(_A1 __x) _NOEXCEPT
 {
-#if __has_builtin(__builtin_llrint)
     return __builtin_llrint((double)__x);
-#else
-    return ::llrint((double)__x);
-#endif
 }
 
 // llround
 
 inline _LIBCPP_HIDE_FROM_ABI long long llround(float __x) _NOEXCEPT
 {
-#if __has_builtin(__builtin_llroundf)
     return __builtin_llroundf(__x);
-#else
-    return ::llroundf(__x);
-#endif
 }
 inline _LIBCPP_HIDE_FROM_ABI long long llround(long double __x) _NOEXCEPT
 {
-#if __has_builtin(__builtin_llroundl)
     return __builtin_llroundl(__x);
-#else
-    return ::llroundl(__x);
-#endif
 }
 
 template <class _A1>
@@ -1332,11 +1252,7 @@
 typename std::enable_if<std::is_integral<_A1>::value, long long>::type
 llround(_A1 __x) _NOEXCEPT
 {
-#if __has_builtin(__builtin_llround)
     return __builtin_llround((double)__x);
-#else
-    return ::llround((double)__x);
-#endif
 }
 
 // log1p
@@ -1373,19 +1289,11 @@
 
 inline _LIBCPP_HIDE_FROM_ABI long lrint(float __x) _NOEXCEPT
 {
-#if __has_builtin(__builtin_lrintf)
     return __builtin_lrintf(__x);
-#else
-    return ::lrintf(__x);
-#endif
 }
 inline _LIBCPP_HIDE_FROM_ABI long lrint(long double __x) _NOEXCEPT
 {
-#if __has_builtin(__builtin_lrintl)
     return __builtin_lrintl(__x);
-#else
-    return ::lrintl(__x);
-#endif
 }
 
 template <class _A1>
@@ -1393,30 +1301,18 @@
 typename std::enable_if<std::is_integral<_A1>::value, long>::type
 lrint(_A1 __x) _NOEXCEPT
 {
-#if __has_builtin(__builtin_lrint)
     return __builtin_lrint((double)__x);
-#else
-    return ::lrint((double)__x);
-#endif
 }
 
 // lround
 
 inline _LIBCPP_HIDE_FROM_ABI long lround(float __x) _NOEXCEPT
 {
-#if __has_builtin(__builtin_lroundf)
     return __builtin_lroundf(__x);
-#else
-    return ::lroundf(__x);
-#endif
 }
 inline _LIBCPP_HIDE_FROM_ABI long lround(long double __x) _NOEXCEPT
 {
-#if __has_builtin(__builtin_lroundl)
     return __builtin_lroundl(__x);
-#else
-    return ::lroundl(__x);
-#endif
 }
 
 template <class _A1>
@@ -1424,11 +1320,7 @@
 typename std::enable_if<std::is_integral<_A1>::value, long>::type
 lround(_A1 __x) _NOEXCEPT
 {
-#if __has_builtin(__builtin_lround)
     return __builtin_lround((double)__x);
-#else
-    return ::lround((double)__x);
-#endif
 }
 
 // nan
@@ -1520,19 +1412,11 @@
 
 inline _LIBCPP_HIDE_FROM_ABI float       rint(float __x) _NOEXCEPT
 {
-#if __has_builtin(__builtin_rintf)
     return __builtin_rintf(__x);
-#else
-    return ::rintf(__x);
-#endif
 }
 inline _LIBCPP_HIDE_FROM_ABI long double rint(long double __x) _NOEXCEPT
 {
-#if __has_builtin(__builtin_rintl)
     return __builtin_rintl(__x);
-#else
-    return ::rintl(__x);
-#endif
 }
 
 template <class _A1>
@@ -1540,30 +1424,18 @@
 typename std::enable_if<std::is_integral<_A1>::value, double>::type
 rint(_A1 __x) _NOEXCEPT
 {
-#if __has_builtin(__builtin_rint)
     return __builtin_rint((double)__x);
-#else
-    return ::rint((double)__x);
-#endif
 }
 
 // round
 
 inline _LIBCPP_HIDE_FROM_ABI float       round(float __x) _NOEXCEPT
 {
-#if __has_builtin(__builtin_round)
     return __builtin_round(__x);
-#else
-    return ::round(__x);
-#endif
 }
 inline _LIBCPP_HIDE_FROM_ABI long double round(long double __x) _NOEXCEPT
 {
-#if __has_builtin(__builtin_roundl)
     return __builtin_roundl(__x);
-#else
-    return ::roundl(__x);
-#endif
 }
 
 template <class _A1>
@@ -1571,11 +1443,7 @@
 typename std::enable_if<std::is_integral<_A1>::value, double>::type
 round(_A1 __x) _NOEXCEPT
 {
-#if __has_builtin(__builtin_round)
     return __builtin_round((double)__x);
-#else
-    return ::round((double)__x);
-#endif
 }
 
 // scalbln
@@ -1612,19 +1480,11 @@
 
 inline _LIBCPP_HIDE_FROM_ABI float       trunc(float __x) _NOEXCEPT
 {
-#if __has_builtin(__builtin_trunc)
     return __builtin_trunc(__x);
-#else
-    return ::trunc(__x);
-#endif
 }
 inline _LIBCPP_HIDE_FROM_ABI long double trunc(long double __x) _NOEXCEPT
 {
-#if __has_builtin(__builtin_truncl)
     return __builtin_truncl(__x);
-#else
-    return ::truncl(__x);
-#endif
 }
 
 template <class _A1>
@@ -1632,11 +1492,7 @@
 typename std::enable_if<std::is_integral<_A1>::value, double>::type
 trunc(_A1 __x) _NOEXCEPT
 {
-#if __has_builtin(__builtin_trunc)
     return __builtin_trunc((double)__x);
-#else
-    return ::trunc((double)__x);
-#endif
 }
 
 } // extern "C++"