diff --git a/libcxx/include/__config b/libcxx/include/__config
--- a/libcxx/include/__config
+++ b/libcxx/include/__config
@@ -837,12 +837,6 @@
 #define _LIBCPP_HAS_NO_RANGES
 #endif
 
-#ifdef _LIBCPP_CXX03_LANG
-#  define _LIBCPP_DEFAULT {}
-#else
-#  define _LIBCPP_DEFAULT = default;
-#endif
-
 #ifdef __GNUC__
 #  define _LIBCPP_NOALIAS __attribute__((__malloc__))
 #else
diff --git a/libcxx/include/__memory/allocator.h b/libcxx/include/__memory/allocator.h
--- a/libcxx/include/__memory/allocator.h
+++ b/libcxx/include/__memory/allocator.h
@@ -89,7 +89,7 @@
     typedef true_type   is_always_equal;
 
     _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX17
-    allocator() _NOEXCEPT _LIBCPP_DEFAULT
+    allocator() _NOEXCEPT = default;
 
     template <class _Up>
     _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX17
@@ -171,7 +171,7 @@
     typedef true_type   is_always_equal;
 
     _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX17
-    allocator() _NOEXCEPT _LIBCPP_DEFAULT
+    allocator() _NOEXCEPT = default;
 
     template <class _Up>
     _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX17
diff --git a/libcxx/include/atomic b/libcxx/include/atomic
--- a/libcxx/include/atomic
+++ b/libcxx/include/atomic
@@ -1443,7 +1443,7 @@
     static_assert(is_trivially_copyable<_Tp>::value,
       "std::atomic<T> requires that 'T' be a trivially copyable type");
 
-  _LIBCPP_INLINE_VISIBILITY __cxx_atomic_impl() _NOEXCEPT _LIBCPP_DEFAULT
+  _LIBCPP_INLINE_VISIBILITY __cxx_atomic_impl() _NOEXCEPT = default;
   _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR explicit __cxx_atomic_impl(_Tp value) _NOEXCEPT
     : _Base(value) {}
 };
@@ -1644,7 +1644,7 @@
     __atomic_base() noexcept(is_nothrow_default_constructible_v<_Tp>) : __a_(_Tp()) {}
 #else
     _LIBCPP_INLINE_VISIBILITY
-    __atomic_base() _NOEXCEPT _LIBCPP_DEFAULT
+    __atomic_base() _NOEXCEPT = default;
 #endif
 
     _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR
@@ -1673,7 +1673,7 @@
     typedef __atomic_base<_Tp, false> __base;
 
     _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX17
-    __atomic_base() _NOEXCEPT _LIBCPP_DEFAULT
+    __atomic_base() _NOEXCEPT = default;
 
     _LIBCPP_INLINE_VISIBILITY
     _LIBCPP_CONSTEXPR __atomic_base(_Tp __d) _NOEXCEPT : __base(__d) {}
@@ -1762,7 +1762,7 @@
     atomic() = default;
 #else
     _LIBCPP_INLINE_VISIBILITY
-    atomic() _NOEXCEPT _LIBCPP_DEFAULT
+    atomic() _NOEXCEPT = default;
 #endif
 
     _LIBCPP_INLINE_VISIBILITY
@@ -1790,7 +1790,7 @@
     typedef ptrdiff_t difference_type;
 
     _LIBCPP_INLINE_VISIBILITY
-    atomic() _NOEXCEPT _LIBCPP_DEFAULT
+    atomic() _NOEXCEPT = default;
 
     _LIBCPP_INLINE_VISIBILITY
     _LIBCPP_CONSTEXPR atomic(_Tp* __d) _NOEXCEPT : __base(__d) {}
@@ -2432,7 +2432,7 @@
     atomic_flag() _NOEXCEPT : __a_(false) {}
 #else
     _LIBCPP_INLINE_VISIBILITY
-    atomic_flag() _NOEXCEPT _LIBCPP_DEFAULT
+    atomic_flag() _NOEXCEPT = default;
 #endif
 
     _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR
diff --git a/libcxx/include/system_error b/libcxx/include/system_error
--- a/libcxx/include/system_error
+++ b/libcxx/include/system_error
@@ -206,7 +206,7 @@
     error_category() _NOEXCEPT;
 #else
     _LIBCPP_INLINE_VISIBILITY
-    _LIBCPP_CONSTEXPR_AFTER_CXX11 error_category() _NOEXCEPT _LIBCPP_DEFAULT
+    _LIBCPP_CONSTEXPR_AFTER_CXX11 error_category() _NOEXCEPT = default;
 #endif
 private:
     error_category(const error_category&);// = delete;