Index: libcxx/include/__config
===================================================================
--- libcxx/include/__config
+++ libcxx/include/__config
@@ -114,6 +114,12 @@
 #  define _LIBCPP_ABI_DO_NOT_EXPORT_BASIC_STRING_COMMON
 // Remove vector base class
 #  define _LIBCPP_ABI_DO_NOT_EXPORT_VECTOR_BASE_COMMON
+#  if !defined(__GLIBCXX__)
+// Add a move constructor and move assignment operator, and inline parts of the
+// definitions of the constructors, assignment operators, and destructor to
+// enable optimizing away everything if the exception_ptr is empty.
+#    define _LIBCPP_ABI_OPTIMIZED_EXCEPTION_PTR
+#  endif
 #elif _LIBCPP_ABI_VERSION == 1
 #  if !defined(_LIBCPP_OBJECT_FORMAT_COFF)
 // Enable compiling copies of now inline methods into the dylib to support
Index: libcxx/include/exception
===================================================================
--- libcxx/include/exception
+++ libcxx/include/exception
@@ -143,13 +143,59 @@
 class _LIBCPP_TYPE_VIS exception_ptr
 {
     void* __ptr_;
+
+#ifdef _LIBCPP_ABI_OPTIMIZED_EXCEPTION_PTR
+    void __incr_refcount() _NOEXCEPT;
+    void __decr_refcount() _NOEXCEPT;
+#endif // _LIBCPP_ABI_OPTIMIZED_EXCEPTION_PTR
+
 public:
     _LIBCPP_INLINE_VISIBILITY exception_ptr() _NOEXCEPT : __ptr_() {}
     _LIBCPP_INLINE_VISIBILITY exception_ptr(nullptr_t) _NOEXCEPT : __ptr_() {}
 
+#ifndef _LIBCPP_ABI_OPTIMIZED_EXCEPTION_PTR
     exception_ptr(const exception_ptr&) _NOEXCEPT;
     exception_ptr& operator=(const exception_ptr&) _NOEXCEPT;
     ~exception_ptr() _NOEXCEPT;
+#else
+    exception_ptr(const exception_ptr& __rhs) _NOEXCEPT : __ptr_(__rhs.__ptr_) {
+        if (__rhs.__ptr_ != nullptr)
+            __incr_refcount();
+    }
+    exception_ptr(exception_ptr&& __rhs) _NOEXCEPT : __ptr_(__rhs.__ptr_) {
+        __rhs.__ptr_ = nullptr;
+    }
+
+    exception_ptr& operator=(const exception_ptr& __rhs) _NOEXCEPT {
+        if (__ptr_ != __rhs.__ptr_) {
+            if (__ptr_ != nullptr)
+                __decr_refcount();
+            __ptr_ = __rhs.__ptr_;
+            if (__ptr_ != nullptr)
+                __incr_refcount();
+        }
+        return *this;
+    }
+    exception_ptr& operator=(exception_ptr&& __rhs) _NOEXCEPT {
+        if (__ptr_ != nullptr)
+            __decr_refcount();
+        __ptr_ = __rhs.__ptr_;
+        __rhs.__ptr_ = nullptr;
+        return *this;
+    }
+
+    ~exception_ptr() _NOEXCEPT {
+        if (__ptr_ != nullptr)
+            __decr_refcount();
+    }
+
+    _LIBCPP_INLINE_VISIBILITY
+    void swap(exception_ptr& __rhs) _NOEXCEPT {
+        void *__tmp = __ptr_;
+        __ptr_ = __rhs.__ptr_;
+        __rhs.__ptr_ = __tmp;
+    }
+#endif // _LIBCPP_ABI_OPTIMIZED_EXCEPTION_PTR
 
     _LIBCPP_INLINE_VISIBILITY explicit operator bool() const _NOEXCEPT
     {return __ptr_ != nullptr;}
@@ -166,6 +212,12 @@
     friend _LIBCPP_FUNC_VIS void rethrow_exception(exception_ptr);
 };
 
+#ifdef _LIBCPP_ABI_OPTIMIZED_EXCEPTION_PTR
+inline _LIBCPP_INLINE_VISIBILITY void
+swap(exception_ptr& __lhs, exception_ptr& __rhs) _NOEXCEPT
+{ __lhs.swap(__rhs); }
+#endif // _LIBCPP_ABI_OPTIMIZED_EXCEPTION_PTR
+
 template<class _Ep>
 _LIBCPP_INLINE_VISIBILITY exception_ptr
 make_exception_ptr(_Ep __e) _NOEXCEPT
Index: libcxx/src/support/runtime/exception_pointer_cxxabi.ipp
===================================================================
--- libcxx/src/support/runtime/exception_pointer_cxxabi.ipp
+++ libcxx/src/support/runtime/exception_pointer_cxxabi.ipp
@@ -13,16 +13,25 @@
 
 namespace std {
 
+#ifndef _LIBCPP_ABI_OPTIMIZED_EXCEPTION_PTR
 exception_ptr::~exception_ptr() noexcept {
+#else
+void exception_ptr::__decr_refcount() noexcept {
+#endif // _LIBCPP_ABI_OPTIMIZED_EXCEPTION_PTR
   __cxa_decrement_exception_refcount(__ptr_);
 }
 
+#ifndef _LIBCPP_ABI_OPTIMIZED_EXCEPTION_PTR
 exception_ptr::exception_ptr(const exception_ptr& other) noexcept
     : __ptr_(other.__ptr_)
+#else
+void exception_ptr::__incr_refcount() noexcept
+#endif // _LIBCPP_ABI_OPTIMIZED_EXCEPTION_PTR
 {
     __cxa_increment_exception_refcount(__ptr_);
 }
 
+#ifndef _LIBCPP_ABI_OPTIMIZED_EXCEPTION_PTR
 exception_ptr& exception_ptr::operator=(const exception_ptr& other) noexcept
 {
     if (__ptr_ != other.__ptr_)
@@ -33,6 +42,7 @@
     }
     return *this;
 }
+#endif // _LIBCPP_ABI_OPTIMIZED_EXCEPTION_PTR
 
 nested_exception::nested_exception() noexcept
     : __ptr_(current_exception())
Index: libcxx/src/support/runtime/exception_pointer_unimplemented.ipp
===================================================================
--- libcxx/src/support/runtime/exception_pointer_unimplemented.ipp
+++ libcxx/src/support/runtime/exception_pointer_unimplemented.ipp
@@ -12,27 +12,37 @@
 
 namespace std {
 
+#ifndef _LIBCPP_ABI_OPTIMIZED_EXCEPTION_PTR
 exception_ptr::~exception_ptr() noexcept
+#else
+void exception_ptr::__decr_refcount() noexcept
+#endif // _LIBCPP_ABI_OPTIMIZED_EXCEPTION_PTR
 {
 #  warning exception_ptr not yet implemented
   fprintf(stderr, "exception_ptr not yet implemented\n");
   ::abort();
 }
 
+#ifndef _LIBCPP_ABI_OPTIMIZED_EXCEPTION_PTR
 exception_ptr::exception_ptr(const exception_ptr& other) noexcept
     : __ptr_(other.__ptr_)
+#else
+void exception_ptr::__incr_refcount() noexcept
+#endif // _LIBCPP_ABI_OPTIMIZED_EXCEPTION_PTR
 {
 #  warning exception_ptr not yet implemented
   fprintf(stderr, "exception_ptr not yet implemented\n");
   ::abort();
 }
 
+#ifndef _LIBCPP_ABI_OPTIMIZED_EXCEPTION_PTR
 exception_ptr& exception_ptr::operator=(const exception_ptr& other) noexcept
 {
 #  warning exception_ptr not yet implemented
   fprintf(stderr, "exception_ptr not yet implemented\n");
   ::abort();
 }
+#endif // _LIBCPP_ABI_OPTIMIZED_EXCEPTION_PTR
 
 nested_exception::nested_exception() noexcept
     : __ptr_(current_exception())