Index: libcxx/include/exception
===================================================================
--- libcxx/include/exception
+++ libcxx/include/exception
@@ -141,16 +141,72 @@
 
 #ifndef _LIBCPP_ABI_MICROSOFT
 
+// Previously, the copy constructor, assignment operator, and destructor of
+// exception_ptr were defined out-of-line, which prevented useful compiler
+// optimizations (especially for the case where the exception_ptr is known to
+// be empty). Changing the out-of-line definitions to inline definitions is an
+// ABI break, however; to prevent this, we have to make sure the symbols
+// remain available in the libc++ library, in addition to being defined inline
+// here in this header. To this end, we use the __gnu_inline__ attribute via the
+// _LIBCPP_EXCEPTION_PTR_GNU_INLINE macro: The macro is defined as empty in
+// src/exception.cpp, forcing the definitions of the aforementioned functions to
+// be emitted and included in the library. When users of libc++ (re)compile their
+// code, however, the _LIBCPP_EXCEPTION_PTR_GNU_INLINE macro won't be defined,
+// and thus the __gnu_inline__ attribute will suppress generation of these
+// functions while making their definitions available for inlining.
+#ifndef _LIBCPP_EXCEPTION_PTR_GNU_INLINE
+#if !__has_attribute(__gnu_inline__)
+#error "this compiler does not appear to support the __gnu_inline__ attribute!"
+#endif
+
+#ifndef __GLIBCXX__
+#define _LIBCPP_EXCEPTION_PTR_GNU_INLINE __attribute__((__gnu_inline__)) inline
+#else
+#define _LIBCPP_EXCEPTION_PTR_GNU_INLINE /*empty*/
+#endif
+#endif
+
+_LIBCPP_DIAGNOSTIC_PUSH
+_LIBCPP_CLANG_DIAGNOSTIC_IGNORED("-Wgnu-inline-cpp-without-extern")
+
 class _LIBCPP_TYPE_VIS exception_ptr
 {
     void* __ptr_;
+
+#ifndef __GLIBCXX__
+    void __incr_refcount() _NOEXCEPT;
+    void __decr_refcount() _NOEXCEPT;
+#endif
+
 public:
     _LIBCPP_INLINE_VISIBILITY exception_ptr() _NOEXCEPT : __ptr_() {}
     _LIBCPP_INLINE_VISIBILITY exception_ptr(nullptr_t) _NOEXCEPT : __ptr_() {}
 
-    exception_ptr(const exception_ptr&) _NOEXCEPT;
-    exception_ptr& operator=(const exception_ptr&) _NOEXCEPT;
-    ~exception_ptr() _NOEXCEPT;
+    _LIBCPP_EXCEPTION_PTR_GNU_INLINE exception_ptr(const exception_ptr&) _NOEXCEPT;
+    _LIBCPP_EXCEPTION_PTR_GNU_INLINE exception_ptr& operator=(const exception_ptr&) _NOEXCEPT;
+    _LIBCPP_EXCEPTION_PTR_GNU_INLINE ~exception_ptr() _NOEXCEPT;
+
+    _LIBCPP_INLINE_VISIBILITY exception_ptr(exception_ptr&& __rhs) _NOEXCEPT : __ptr_(__rhs.__ptr_) {
+        __rhs.__ptr_ = nullptr;
+    }
+
+    // Move assignment is not available for the glibcxx ABI because it
+    // doesn't have __decr_refcount().
+#ifndef __GLIBCXX__
+    _LIBCPP_INLINE_VISIBILITY exception_ptr& operator=(exception_ptr&& __rhs) _NOEXCEPT {
+        if (__ptr_ != nullptr)
+            __decr_refcount();
+        __ptr_ = __rhs.__ptr_;
+        __rhs.__ptr_ = nullptr;
+        return *this;
+    }
+#endif
+
+    _LIBCPP_INLINE_VISIBILITY void swap(exception_ptr& __rhs) _NOEXCEPT {
+        void *__tmp = __ptr_;
+        __ptr_ = __rhs.__ptr_;
+        __rhs.__ptr_ = __tmp;
+    }
 
     _LIBCPP_INLINE_VISIBILITY explicit operator bool() const _NOEXCEPT
     {return __ptr_ != nullptr;}
@@ -167,6 +223,44 @@
     friend _LIBCPP_FUNC_VIS void rethrow_exception(exception_ptr);
 };
 
+// If __GLIBCXX__ is defined, the exception_ptr from libsupc++ is used (which
+// works because it happens to have the same layout as our exception_ptr).
+// The constructor, assignment operator, and destructor should just delegate
+// to the libsupc++ implementations then, so we don't provide definitions for
+// them here.
+#ifndef __GLIBCXX__
+_LIBCPP_EXCEPTION_PTR_GNU_INLINE
+exception_ptr::exception_ptr(const exception_ptr& __rhs) _NOEXCEPT : __ptr_(__rhs.__ptr_) {
+    if (__rhs.__ptr_ != nullptr)
+        __incr_refcount();
+}
+
+_LIBCPP_EXCEPTION_PTR_GNU_INLINE
+exception_ptr& 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;
+}
+
+_LIBCPP_EXCEPTION_PTR_GNU_INLINE
+exception_ptr::~exception_ptr() _NOEXCEPT {
+    if (__ptr_ != nullptr)
+        __decr_refcount();
+}
+#endif // __GLIBCXX__
+
+_LIBCPP_DIAGNOSTIC_POP // pops CLANG_DIAGNOSTIC_IGNORED("-Wgnu-inline-cpp-without-extern")
+
+inline _LIBCPP_INLINE_VISIBILITY void
+swap(exception_ptr& __lhs, exception_ptr& __rhs) _NOEXCEPT {
+    __lhs.swap(__rhs);
+}
+
 template<class _Ep>
 _LIBCPP_INLINE_VISIBILITY exception_ptr
 make_exception_ptr(_Ep __e) _NOEXCEPT
Index: libcxx/src/exception.cpp
===================================================================
--- libcxx/src/exception.cpp
+++ libcxx/src/exception.cpp
@@ -6,7 +6,9 @@
 //
 //===----------------------------------------------------------------------===//
 
+#define _LIBCPP_EXCEPTION_PTR_GNU_INLINE /*empty*/
 #include <exception>
+
 #include <new>
 #include <typeinfo>
 
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
@@ -13,27 +13,15 @@
 
 namespace std {
 
-exception_ptr::~exception_ptr() noexcept {
+void exception_ptr::__decr_refcount() noexcept {
   __cxa_decrement_exception_refcount(__ptr_);
 }
 
-exception_ptr::exception_ptr(const exception_ptr& other) noexcept
-    : __ptr_(other.__ptr_)
+void exception_ptr::__incr_refcount() noexcept
 {
     __cxa_increment_exception_refcount(__ptr_);
 }
 
-exception_ptr& exception_ptr::operator=(const exception_ptr& other) noexcept
-{
-    if (__ptr_ != other.__ptr_)
-    {
-        __cxa_increment_exception_refcount(other.__ptr_);
-        __cxa_decrement_exception_refcount(__ptr_);
-        __ptr_ = other.__ptr_;
-    }
-    return *this;
-}
-
 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
@@ -12,22 +12,14 @@
 
 namespace std {
 
-exception_ptr::~exception_ptr() noexcept
+void exception_ptr::__decr_refcount() noexcept
 {
 #  warning exception_ptr not yet implemented
   fprintf(stderr, "exception_ptr not yet implemented\n");
   ::abort();
 }
 
-exception_ptr::exception_ptr(const exception_ptr& other) noexcept
-    : __ptr_(other.__ptr_)
-{
-#  warning exception_ptr not yet implemented
-  fprintf(stderr, "exception_ptr not yet implemented\n");
-  ::abort();
-}
-
-exception_ptr& exception_ptr::operator=(const exception_ptr& other) noexcept
+void exception_ptr::__incr_refcount() noexcept
 {
 #  warning exception_ptr not yet implemented
   fprintf(stderr, "exception_ptr not yet implemented\n");