diff --git a/libcxx/include/type_traits b/libcxx/include/type_traits
index c7e4749259ad..f954a819ca82 100644
--- a/libcxx/include/type_traits
+++ b/libcxx/include/type_traits
@@ -4007,9 +4007,11 @@ inline constexpr bool is_constant_evaluated() noexcept {
 }
 #endif
 
-_LIBCPP_CONSTEXPR bool __libcpp_is_constant_evaluated() _NOEXCEPT { return __builtin_is_constant_evaluated(); }
+inline _LIBCPP_CONSTEXPR
+bool __libcpp_is_constant_evaluated() _NOEXCEPT { return __builtin_is_constant_evaluated(); }
 #else
-_LIBCPP_CONSTEXPR bool __libcpp_is_constant_evaluated() _NOEXCEPT { return false; }
+inline _LIBCPP_CONSTEXPR
+bool __libcpp_is_constant_evaluated() _NOEXCEPT { return false; }
 #endif
 
 template <class _CharT>