diff --git a/lib/libcxx/include/__config b/lib/libcxx/include/__config
index a3748e5d4f..d9a47343da 100644
--- a/lib/libcxx/include/__config
+++ b/lib/libcxx/include/__config
@@ -20,9 +20,21 @@
 #  pragma GCC system_header
 #endif
 
+#if defined(__apple_build_version__)
+#  define _LIBCPP_COMPILER_CLANG_BASED
+#  define _LIBCPP_APPLE_CLANG_VER (__apple_build_version__ / 10000)
+#elif defined(__clang__)
+#  define _LIBCPP_COMPILER_CLANG_BASED
+#  define _LIBCPP_CLANG_VER (__clang_major__ * 100 + __clang_minor__)
+#elif defined(__GNUC__)
+#  define _LIBCPP_COMPILER_GCC
+#elif defined(_MSC_VER)
+#  define _LIBCPP_COMPILER_MSVC
+#endif
+
 #ifdef __cplusplus
 
-#  define _LIBCPP_VERSION 15000
+#  define _LIBCPP_VERSION 15003
 
 #  define _LIBCPP_CONCAT_IMPL(_X, _Y) _X##_Y
 #  define _LIBCPP_CONCAT(_X, _Y) _LIBCPP_CONCAT_IMPL(_X, _Y)
@@ -196,18 +208,6 @@
 #    define __has_include(...) 0
 #  endif
 
-#  if defined(__apple_build_version__)
-#    define _LIBCPP_COMPILER_CLANG_BASED
-#    define _LIBCPP_APPLE_CLANG_VER (__apple_build_version__ / 10000)
-#  elif defined(__clang__)
-#    define _LIBCPP_COMPILER_CLANG_BASED
-#    define _LIBCPP_CLANG_VER (__clang_major__ * 100 + __clang_minor__)
-#  elif defined(__GNUC__)
-#    define _LIBCPP_COMPILER_GCC
-#  elif defined(_MSC_VER)
-#    define _LIBCPP_COMPILER_MSVC
-#  endif
-
 #  if !defined(_LIBCPP_COMPILER_CLANG_BASED) && __cplusplus < 201103L
 #    error "libc++ only supports C++03 with Clang-based compilers. Please enable C++11"
 #  endif
@@ -1099,6 +1099,13 @@ _LIBCPP_BEGIN_NAMESPACE_STD _LIBCPP_END_NAMESPACE_STD
 #    define _LIBCPP_ENABLE_CXX17_REMOVED_UNARY_BINARY_FUNCTION
 #  endif // _LIBCPP_ENABLE_CXX17_REMOVED_FEATURES
 
+// Leave the deprecation notices in by default, but don't remove unary_function and
+// binary_function entirely just yet. That way, folks will have one release to act
+// on the deprecation warnings.
+#  ifndef _LIBCPP_ENABLE_CXX17_REMOVED_UNARY_BINARY_FUNCTION
+#    define _LIBCPP_ENABLE_CXX17_REMOVED_UNARY_BINARY_FUNCTION
+#  endif
+
 #  if defined(_LIBCPP_ENABLE_CXX20_REMOVED_FEATURES)
 #    define _LIBCPP_ENABLE_CXX20_REMOVED_ALLOCATOR_MEMBERS
 #    define _LIBCPP_ENABLE_CXX20_REMOVED_ALLOCATOR_VOID_SPECIALIZATION
diff --git a/lib/libcxx/include/__functional/function.h b/lib/libcxx/include/__functional/function.h
index db3af6e241..55b607f3f8 100644
--- a/lib/libcxx/include/__functional/function.h
+++ b/lib/libcxx/include/__functional/function.h
@@ -883,7 +883,7 @@ template <class _Rp, class... _ArgTypes> class __policy_func<_Rp(_ArgTypes...)>
 #endif // _LIBCPP_NO_RTTI
 };
 
-#if defined(_LIBCPP_HAS_BLOCKS_RUNTIME) && !defined(_LIBCPP_HAS_OBJC_ARC)
+#if defined(_LIBCPP_HAS_BLOCKS_RUNTIME)
 
 extern "C" void *_Block_copy(const void *);
 extern "C" void _Block_release(const void *);
@@ -898,14 +898,22 @@ class __func<_Rp1(^)(_ArgTypes1...), _Alloc, _Rp(_ArgTypes...)>
 public:
     _LIBCPP_INLINE_VISIBILITY
     explicit __func(__block_type const& __f)
+#ifdef _LIBCPP_HAS_OBJC_ARC
+        : __f_(__f)
+#else
         : __f_(reinterpret_cast<__block_type>(__f ? _Block_copy(__f) : nullptr))
+#endif
     { }
 
     // [TODO] add && to save on a retain
 
     _LIBCPP_INLINE_VISIBILITY
     explicit __func(__block_type __f, const _Alloc& /* unused */)
+#ifdef _LIBCPP_HAS_OBJC_ARC
+        : __f_(__f)
+#else
         : __f_(reinterpret_cast<__block_type>(__f ? _Block_copy(__f) : nullptr))
+#endif
     { }
 
     virtual __base<_Rp(_ArgTypes...)>* __clone() const {
@@ -921,8 +929,10 @@ public:
     }
 
     virtual void destroy() _NOEXCEPT {
+#ifndef _LIBCPP_HAS_OBJC_ARC
         if (__f_)
             _Block_release(__f_);
+#endif
         __f_ = 0;
     }
 
@@ -950,7 +960,7 @@ public:
 #endif // _LIBCPP_NO_RTTI
 };
 
-#endif // _LIBCPP_HAS_EXTENSION_BLOCKS && !_LIBCPP_HAS_OBJC_ARC
+#endif // _LIBCPP_HAS_EXTENSION_BLOCKS
 
 } // namespace __function
 
diff --git a/lib/libcxx/include/atomic b/lib/libcxx/include/atomic
index 92da4820e9..3a93b9b0a1 100644
--- a/lib/libcxx/include/atomic
+++ b/lib/libcxx/include/atomic
@@ -1113,6 +1113,12 @@ _Tp kill_dependency(_Tp __y) _NOEXCEPT
 # define ATOMIC_POINTER_LOCK_FREE   __GCC_ATOMIC_POINTER_LOCK_FREE
 #endif
 
+template <class _Tp>
+struct __libcpp_is_always_lock_free {
+  // __atomic_always_lock_free is available in all Standard modes
+  static const bool __value = __atomic_always_lock_free(sizeof(_Tp), 0);
+};
+
 #ifdef _LIBCPP_ATOMIC_ONLY_USE_BUILTINS
 
 template<typename _Tp>
@@ -1404,42 +1410,8 @@ _Tp __cxx_atomic_fetch_xor(__cxx_atomic_lock_impl<_Tp>* __a,
   return __old;
 }
 
-#ifdef __cpp_lib_atomic_is_always_lock_free
-
-template<typename _Tp> struct __cxx_is_always_lock_free {
-    enum { __value = __atomic_always_lock_free(sizeof(_Tp), 0) }; };
-
-#else
-
-template<typename _Tp> struct __cxx_is_always_lock_free { enum { __value = false }; };
-// Implementations must match the C ATOMIC_*_LOCK_FREE macro values.
-template<> struct __cxx_is_always_lock_free<bool> { enum { __value = 2 == ATOMIC_BOOL_LOCK_FREE }; };
-template<> struct __cxx_is_always_lock_free<char> { enum { __value = 2 == ATOMIC_CHAR_LOCK_FREE }; };
-template<> struct __cxx_is_always_lock_free<signed char> { enum { __value = 2 == ATOMIC_CHAR_LOCK_FREE }; };
-template<> struct __cxx_is_always_lock_free<unsigned char> { enum { __value = 2 == ATOMIC_CHAR_LOCK_FREE }; };
-#ifndef _LIBCPP_HAS_NO_CHAR8_T
-template<> struct __cxx_is_always_lock_free<char8_t> { enum { __value = 2 == ATOMIC_CHAR8_T_LOCK_FREE }; };
-#endif
-template<> struct __cxx_is_always_lock_free<char16_t> { enum { __value = 2 == ATOMIC_CHAR16_T_LOCK_FREE }; };
-template<> struct __cxx_is_always_lock_free<char32_t> { enum { __value = 2 == ATOMIC_CHAR32_T_LOCK_FREE }; };
-#ifndef _LIBCPP_HAS_NO_WIDE_CHARACTERS
-template<> struct __cxx_is_always_lock_free<wchar_t> { enum { __value = 2 == ATOMIC_WCHAR_T_LOCK_FREE }; };
-#endif
-template<> struct __cxx_is_always_lock_free<short> { enum { __value = 2 == ATOMIC_SHORT_LOCK_FREE }; };
-template<> struct __cxx_is_always_lock_free<unsigned short> { enum { __value = 2 == ATOMIC_SHORT_LOCK_FREE }; };
-template<> struct __cxx_is_always_lock_free<int> { enum { __value = 2 == ATOMIC_INT_LOCK_FREE }; };
-template<> struct __cxx_is_always_lock_free<unsigned int> { enum { __value = 2 == ATOMIC_INT_LOCK_FREE }; };
-template<> struct __cxx_is_always_lock_free<long> { enum { __value = 2 == ATOMIC_LONG_LOCK_FREE }; };
-template<> struct __cxx_is_always_lock_free<unsigned long> { enum { __value = 2 == ATOMIC_LONG_LOCK_FREE }; };
-template<> struct __cxx_is_always_lock_free<long long> { enum { __value = 2 == ATOMIC_LLONG_LOCK_FREE }; };
-template<> struct __cxx_is_always_lock_free<unsigned long long> { enum { __value = 2 == ATOMIC_LLONG_LOCK_FREE }; };
-template<typename _Tp> struct __cxx_is_always_lock_free<_Tp*> { enum { __value = 2 == ATOMIC_POINTER_LOCK_FREE }; };
-template<> struct __cxx_is_always_lock_free<std::nullptr_t> { enum { __value = 2 == ATOMIC_POINTER_LOCK_FREE }; };
-
-#endif //__cpp_lib_atomic_is_always_lock_free
-
 template <typename _Tp,
-          typename _Base = typename conditional<__cxx_is_always_lock_free<_Tp>::__value,
+          typename _Base = typename conditional<__libcpp_is_always_lock_free<_Tp>::__value,
                                                 __cxx_atomic_base_impl<_Tp>,
                                                 __cxx_atomic_lock_impl<_Tp> >::type>
 #else
@@ -1561,7 +1533,7 @@ struct __atomic_base  // false
     mutable __cxx_atomic_impl<_Tp> __a_;
 
 #if defined(__cpp_lib_atomic_is_always_lock_free)
-  static _LIBCPP_CONSTEXPR bool is_always_lock_free = __atomic_always_lock_free(sizeof(__a_), 0);
+  static _LIBCPP_CONSTEXPR bool is_always_lock_free = __libcpp_is_always_lock_free<__cxx_atomic_impl<_Tp> >::__value;
 #endif
 
     _LIBCPP_INLINE_VISIBILITY
@@ -2664,7 +2636,7 @@ typedef atomic<uintmax_t> atomic_uintmax_t;
 // atomic_*_lock_free : prefer the contention type most highly, then the largest lock-free type
 
 #ifdef __cpp_lib_atomic_is_always_lock_free
-# define _LIBCPP_CONTENTION_LOCK_FREE __atomic_always_lock_free(sizeof(__cxx_contention_t), 0)
+# define _LIBCPP_CONTENTION_LOCK_FREE ::std::__libcpp_is_always_lock_free<__cxx_contention_t>::__value
 #else
 # define _LIBCPP_CONTENTION_LOCK_FREE false
 #endif
diff --git a/lib/libcxx/include/regex b/lib/libcxx/include/regex
index 850fe099df..26887e84bf 100644
--- a/lib/libcxx/include/regex
+++ b/lib/libcxx/include/regex
@@ -1355,7 +1355,7 @@ inline _LIBCPP_INLINE_VISIBILITY
 unsigned char __to_lower(unsigned char __c)
 {
 #if defined(__MVS__) && !defined(__NATIVE_ASCII_F)
-    return c & 0xBF;
+    return __c & 0xBF;
 #else
     return __c | 0x20;
 #endif
diff --git a/lib/libcxx/include/stdatomic.h b/lib/libcxx/include/stdatomic.h
index d9550c4406..ff2a5682f5 100644
--- a/lib/libcxx/include/stdatomic.h
+++ b/lib/libcxx/include/stdatomic.h
@@ -121,7 +121,7 @@ using std::atomic_signal_fence                         // see below
 #  pragma GCC system_header
 #endif
 
-#if _LIBCPP_STD_VER > 20
+#if defined(__cplusplus) && _LIBCPP_STD_VER > 20
 
 #include <atomic>
 #include <version>
@@ -230,6 +230,6 @@ using std::atomic_thread_fence _LIBCPP_USING_IF_EXISTS;
 #   include_next <stdatomic.h>
 # endif
 
-#endif // _LIBCPP_STD_VER > 20
+#endif // defined(__cplusplus) && _LIBCPP_STD_VER > 20
 
 #endif // _LIBCPP_STDATOMIC_H
diff --git a/lib/libcxx/include/version b/lib/libcxx/include/version
index 8ffb1747eb..d0c6fe466e 100644
--- a/lib/libcxx/include/version
+++ b/lib/libcxx/include/version
@@ -332,7 +332,7 @@ __cpp_lib_void_t                                        201411L <type_traits>
 # undef  __cpp_lib_execution
 // # define __cpp_lib_execution                            201902L
 # if !defined(_LIBCPP_AVAILABILITY_DISABLE_FTM___cpp_lib_format) && !defined(_LIBCPP_HAS_NO_INCOMPLETE_FORMAT)
-#   define __cpp_lib_format                             202106L
+// #   define __cpp_lib_format                             202106L
 # endif
 # define __cpp_lib_generic_unordered_lookup             201811L
 # define __cpp_lib_int_pow2                             202002L