Index: include/experimental/optional
===================================================================
--- include/experimental/optional
+++ include/experimental/optional
@@ -562,7 +562,7 @@
 
     template <class _Up>
     _LIBCPP_INLINE_VISIBILITY
-    value_type value_or(_Up&& __v) &&
+    constexpr value_type value_or(_Up&& __v) &&
     {
         static_assert(is_move_constructible<value_type>::value,
                       "optional<T>::value_or: T must be move constructible");
Index: include/optional
===================================================================
--- include/optional
+++ include/optional
@@ -893,7 +893,7 @@
 
     template <class _Up>
     _LIBCPP_INLINE_VISIBILITY
-    value_type value_or(_Up&& __v) &&
+    constexpr value_type value_or(_Up&& __v) &&
     {
         static_assert(is_move_constructible_v<value_type>,
                       "optional<T>::value_or: T must be move constructible");