diff --git a/libcxx/include/__memory/compressed_pair.h b/libcxx/include/__memory/compressed_pair.h
--- a/libcxx/include/__memory/compressed_pair.h
+++ b/libcxx/include/__memory/compressed_pair.h
@@ -58,8 +58,8 @@
       : __value_(_VSTD::forward<_Args>(_VSTD::get<_Indexes>(__args))...) {}
 #endif
 
-  _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX17 reference __get() _NOEXCEPT { return __value_; }
-  _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX17 const_reference __get() const _NOEXCEPT { return __value_; }
+  _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR reference __get() _NOEXCEPT { return __value_; }
+  _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR const_reference __get() const _NOEXCEPT { return __value_; }
 
 private:
   _Tp __value_;
@@ -95,8 +95,8 @@
       : __value_type(_VSTD::forward<_Args>(_VSTD::get<_Indexes>(__args))...) {}
 #endif
 
-  _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX17 reference __get() _NOEXCEPT { return *this; }
-  _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX17 const_reference __get() const _NOEXCEPT { return *this; }
+  _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR reference __get() _NOEXCEPT { return *this; }
+  _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR const_reference __get() const _NOEXCEPT { return *this; }
 };
 
 template <class _T1, class _T2>
@@ -140,19 +140,19 @@
                typename __make_tuple_indices<sizeof...(_Args2)>::type()) {}
 #endif
 
-  _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX17 typename _Base1::reference first() _NOEXCEPT {
+  _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR typename _Base1::reference first() _NOEXCEPT {
     return static_cast<_Base1&>(*this).__get();
   }
 
-  _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX17 typename _Base1::const_reference first() const _NOEXCEPT {
+  _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR typename _Base1::const_reference first() const _NOEXCEPT {
     return static_cast<_Base1 const&>(*this).__get();
   }
 
-  _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX17 typename _Base2::reference second() _NOEXCEPT {
+  _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR typename _Base2::reference second() _NOEXCEPT {
     return static_cast<_Base2&>(*this).__get();
   }
 
-  _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX17 typename _Base2::const_reference second() const _NOEXCEPT {
+  _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR typename _Base2::const_reference second() const _NOEXCEPT {
     return static_cast<_Base2 const&>(*this).__get();
   }
 
diff --git a/libcxx/include/string b/libcxx/include/string
--- a/libcxx/include/string
+++ b/libcxx/include/string
@@ -1617,7 +1617,7 @@
         size_type (&__a)[__n_words] = __r_.first().__r.__words;
         if (__libcpp_is_constant_evaluated())
         {
-            __r_.first() = __rep {.__l = __long {}};
+            __r_.first() = __rep();
             return;
         }
         for (unsigned __i = 0; __i < __n_words; ++__i)
@@ -1813,11 +1813,13 @@
     }
 
     _LIBCPP_HIDE_FROM_ABI
-    _LIBCPP_CONSTEVAL void __begin_lifetime(pointer __p, size_t __count)
+    _LIBCPP_CONSTEXPR void __begin_lifetime(pointer __p, size_t __count)
     {
         if (__libcpp_is_constant_evaluated())
-                for (size_t __i {}; __i < __count; ++__i)
-                    new (&__p[__i]) value_type();
+        {
+                for (size_t __i = 0; __i < __count; ++__i)
+                    ::new (&__p[__i]) value_type();
+        }
     }
 
     friend _LIBCPP_CONSTEXPR_AFTER_CXX17 basic_string operator+<>(const basic_string&, const basic_string&);
@@ -1914,7 +1916,7 @@
     __get_db()->__insert_c(this);
 #endif
     if (__libcpp_is_constant_evaluated())
-        __init(size_type{0}, {});
+        __init(size_type{0}, value_type());
     else
         __zero();
 }
@@ -2091,7 +2093,7 @@
     {
         if (__libcpp_is_constant_evaluated())
         {
-            __r_.first() = __rep {.__l = __long {}};
+            __r_.first() = __rep();
             __r_.first().__l = __str.__r_.first().__l;
         }
         else