diff --git a/include/__config b/include/__config
index fea7a96..a943274 100644
--- a/include/__config
+++ b/include/__config
@@ -157,6 +157,15 @@
 #define _LIBCPP_HAS_NO_TRAILING_RETURN
 #endif
 
+// Objective-C++ features (opt-in)
+#if __has_feature(objc_arc)
+#define _LIBCPP_HAS_OBJC_ARC
+#endif
+
+#if __has_feature(objc_arc_weak)
+#define _LIBCPP_HAS_OBJC_ARC_WEAK
+#endif
+
 // Inline namespaces are available in Clang regardless of C++ dialect.
 #define _LIBCPP_BEGIN_NAMESPACE_STD namespace std {inline namespace _LIBCPP_NAMESPACE {
 #define _LIBCPP_END_NAMESPACE_STD  } }
diff --git a/include/memory b/include/memory
index 6f6a8ce..479077f 100644
--- a/include/memory
+++ b/include/memory
@@ -619,6 +619,46 @@
     return (_Tp*)&(char&)__x;
 }
 
+#if defined(_LIBCPP_HAS_OBJC_ARC) && !defined(_LIBCPP_PREDEFINED_OBJC_ARC_ADDRESSOF)
+// Objective-C++ Automatic Reference Counting uses qualified pointers
+// that require special addressof() signatures. When
+// _LIBCPP_PREDEFINED_OBJC_ARC_ADDRESSOF is defined, the compiler
+// itself is providing these definitions. Otherwise, we provide them.
+template <class _Tp>
+inline _LIBCPP_INLINE_VISIBILITY
+__strong _Tp*
+addressof(__strong _Tp& __x) _NOEXCEPT
+{
+  return &__x;
+}
+
+#ifdef _LIBCPP_HAS_OBJC_ARC_WEAK
+template <class _Tp>
+inline _LIBCPP_INLINE_VISIBILITY
+__weak _Tp*
+addressof(__weak _Tp& __x) _NOEXCEPT
+{
+  return &__x;
+}
+#endif
+
+template <class _Tp>
+inline _LIBCPP_INLINE_VISIBILITY
+__autoreleasing _Tp*
+addressof(__autoreleasing _Tp& __x) _NOEXCEPT
+{
+  return &__x;
+}
+
+template <class _Tp>
+inline _LIBCPP_INLINE_VISIBILITY
+__unsafe_unretained _Tp*
+addressof(__unsafe_unretained _Tp& __x) _NOEXCEPT
+{
+  return &__x;
+}
+#endif
+
 template <class _Tp> class allocator;
 
 template <>