diff --git a/contrib/libc++/include/exception b/contrib/libc++/include/exception
index 5b75fb04bbba..51a48c8286d6 100644
--- a/contrib/libc++/include/exception
+++ b/contrib/libc++/include/exception
@@ -143,7 +143,7 @@ public:
         {return !(__x == __y);}
 
     friend exception_ptr current_exception() _NOEXCEPT;
-    _LIBCPP_NORETURN friend void rethrow_exception(exception_ptr);
+    friend void rethrow_exception(exception_ptr);
 };
 
 template<class _Ep>
diff --git a/contrib/libc++/include/iterator b/contrib/libc++/include/iterator
index bcbf3ae4af8c..bc0ce4759ce7 100644
--- a/contrib/libc++/include/iterator
+++ b/contrib/libc++/include/iterator
@@ -317,6 +317,10 @@ template <class T, size_t N> T* end(T (&array)[N]);
 #include <type_traits>
 #include <cstddef>
 #include <iosfwd>
+#if __APPLE__
+#include <Availability.h>
+#endif
+
 #ifdef _LIBCPP_DEBUG
 #include <cassert>
 #endif
@@ -795,7 +799,7 @@ public:
     typedef basic_streambuf<_CharT,_Traits> streambuf_type;
     typedef basic_istream<_CharT,_Traits>   istream_type;
 private:
-    streambuf_type* __sbuf_;
+    mutable streambuf_type* __sbuf_;
 
     class __proxy
     {
@@ -809,13 +813,14 @@ private:
     };
 
     _LIBCPP_INLINE_VISIBILITY
-    void __test_for_eof()
+    bool __test_for_eof() const
     {
         if (__sbuf_ && traits_type::eq_int_type(__sbuf_->sgetc(), traits_type::eof()))
             __sbuf_ = 0;
+        return __sbuf_ == 0;
     }
 public:
-    _LIBCPP_INLINE_VISIBILITY istreambuf_iterator() _NOEXCEPT : __sbuf_(0) {}
+    _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR istreambuf_iterator() _NOEXCEPT : __sbuf_(0) {}
     _LIBCPP_INLINE_VISIBILITY istreambuf_iterator(istream_type& __s) _NOEXCEPT
         : __sbuf_(__s.rdbuf()) {__test_for_eof();}
     _LIBCPP_INLINE_VISIBILITY istreambuf_iterator(streambuf_type* __s) _NOEXCEPT
@@ -828,19 +833,16 @@ public:
     _LIBCPP_INLINE_VISIBILITY char_type* operator->() const {return nullptr;}
     _LIBCPP_INLINE_VISIBILITY istreambuf_iterator& operator++()
         {
-            if (traits_type::eq_int_type(__sbuf_->snextc(), traits_type::eof()))
-                __sbuf_ = 0;
+            __sbuf_->sbumpc();
             return *this;
         }
     _LIBCPP_INLINE_VISIBILITY __proxy              operator++(int)
         {
-            char_type __c = __sbuf_->sgetc();
-            ++(*this);
-            return __proxy(__c, __sbuf_);
+            return __proxy(__sbuf_->sbumpc(), __sbuf_);
         }
 
     _LIBCPP_INLINE_VISIBILITY bool equal(const istreambuf_iterator& __b) const
-        {return (__sbuf_ == 0) == (__b.__sbuf_ == 0);}
+        {return __test_for_eof() == __b.__test_for_eof();}
 };
 
 template <class _CharT, class _Traits>
@@ -882,6 +884,10 @@ public:
     _LIBCPP_INLINE_VISIBILITY ostreambuf_iterator& operator++(int) {return *this;}
     _LIBCPP_INLINE_VISIBILITY bool failed() const _NOEXCEPT {return __sbuf_ == 0;}
 
+#if !defined(__APPLE__) || \
+    (defined(__MAC_OS_X_VERSION_MIN_REQUIRED) && __MAC_OS_X_VERSION_MIN_REQUIRED > __MAC_10_8) || \
+    (defined(__IPHONE_OS_VERSION_MIN_REQUIRED) && __IPHONE_OS_VERSION_MIN_REQUIRED > __IPHONE_6_0)
+
     template <class _Ch, class _Tr>
     friend
     _LIBCPP_HIDDEN
@@ -889,6 +895,7 @@ public:
     __pad_and_output(ostreambuf_iterator<_Ch, _Tr> __s,
                      const _Ch* __ob, const _Ch* __op, const _Ch* __oe,
                      ios_base& __iob, _Ch __fl);
+#endif
 };
 
 template <class _Iter>
diff --git a/contrib/libc++/include/locale b/contrib/libc++/include/locale
index 976c4cf50a17..f04a36b43990 100644
--- a/contrib/libc++/include/locale
+++ b/contrib/libc++/include/locale
@@ -192,6 +192,10 @@ template <class charT> class messages_byname;
 #include <nl_types.h>
 #endif  // !_WIN32
 
+#if __APPLE__
+#include <Availability.h>
+#endif
+
 #include <__undef_min_max>
 
 #if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER)
@@ -1587,6 +1591,10 @@ __pad_and_output(_OutputIterator __s,
     return __s;
 }
 
+#if !defined(__APPLE__) || \
+    (defined(__MAC_OS_X_VERSION_MIN_REQUIRED) && __MAC_OS_X_VERSION_MIN_REQUIRED > __MAC_10_8) || \
+    (defined(__IPHONE_OS_VERSION_MIN_REQUIRED) && __IPHONE_OS_VERSION_MIN_REQUIRED > __IPHONE_6_0)
+
 template <class _CharT, class _Traits>
 _LIBCPP_HIDDEN
 ostreambuf_iterator<_CharT, _Traits>
@@ -1633,6 +1641,8 @@ __pad_and_output(ostreambuf_iterator<_CharT, _Traits> __s,
     return __s;
 }
 
+#endif
+
 template <class _CharT, class _OutputIterator>
 _OutputIterator
 num_put<_CharT, _OutputIterator>::do_put(iter_type __s, ios_base& __iob,