diff --git a/libcxx/include/__memory/shared_ptr.h b/libcxx/include/__memory/shared_ptr.h
--- a/libcxx/include/__memory/shared_ptr.h
+++ b/libcxx/include/__memory/shared_ptr.h
@@ -432,10 +432,17 @@
 
     struct __nat {int __for_bool_;};
 public:
-    _LIBCPP_INLINE_VISIBILITY
-    _LIBCPP_CONSTEXPR shared_ptr() _NOEXCEPT;
-    _LIBCPP_INLINE_VISIBILITY
-    _LIBCPP_CONSTEXPR shared_ptr(nullptr_t) _NOEXCEPT;
+    _LIBCPP_HIDE_FROM_ABI
+    _LIBCPP_CONSTEXPR shared_ptr() _NOEXCEPT
+        : __ptr_(nullptr),
+          __cntrl_(nullptr)
+    { }
+
+    _LIBCPP_HIDE_FROM_ABI
+    _LIBCPP_CONSTEXPR shared_ptr(nullptr_t) _NOEXCEPT
+        : __ptr_(nullptr),
+          __cntrl_(nullptr)
+    { }
 
     template<class _Yp, class = __enable_if_t<
         _And<
@@ -457,638 +464,483 @@
         __enable_weak_this(__p, __p);
     }
 
-    template<class _Yp, class _Dp>
-        shared_ptr(_Yp* __p, _Dp __d,
-                   typename enable_if<__shared_ptr_deleter_ctor_reqs<_Dp, _Yp, element_type>::value, __nat>::type = __nat());
-    template<class _Yp, class _Dp, class _Alloc>
-        shared_ptr(_Yp* __p, _Dp __d, _Alloc __a,
-                   typename enable_if<__shared_ptr_deleter_ctor_reqs<_Dp, _Yp, element_type>::value, __nat>::type = __nat());
-    template <class _Dp> shared_ptr(nullptr_t __p, _Dp __d);
-    template <class _Dp, class _Alloc> shared_ptr(nullptr_t __p, _Dp __d, _Alloc __a);
-    template<class _Yp> _LIBCPP_INLINE_VISIBILITY shared_ptr(const shared_ptr<_Yp>& __r, element_type* __p) _NOEXCEPT;
-    _LIBCPP_INLINE_VISIBILITY
-    shared_ptr(const shared_ptr& __r) _NOEXCEPT;
-    template<class _Yp>
-        _LIBCPP_INLINE_VISIBILITY
-        shared_ptr(const shared_ptr<_Yp>& __r,
-                   typename enable_if<__compatible_with<_Yp, _Tp>::value, __nat>::type = __nat())
-                       _NOEXCEPT;
-    _LIBCPP_INLINE_VISIBILITY
-    shared_ptr(shared_ptr&& __r) _NOEXCEPT;
-    template<class _Yp> _LIBCPP_INLINE_VISIBILITY  shared_ptr(shared_ptr<_Yp>&& __r,
-                   typename enable_if<__compatible_with<_Yp, _Tp>::value, __nat>::type = __nat())
-                       _NOEXCEPT;
-    template<class _Yp> explicit shared_ptr(const weak_ptr<_Yp>& __r,
-                   typename enable_if<__compatible_with<_Yp, _Tp>::value, __nat>::type = __nat());
-#if _LIBCPP_STD_VER <= 14 || defined(_LIBCPP_ENABLE_CXX17_REMOVED_AUTO_PTR)
-    template<class _Yp>
-        shared_ptr(auto_ptr<_Yp>&& __r,
-                   typename enable_if<is_convertible<_Yp*, element_type*>::value, __nat>::type = __nat());
-#endif
-    template <class _Yp, class _Dp>
-        shared_ptr(unique_ptr<_Yp, _Dp>&&,
-                   typename enable_if
-                   <
-                       !is_lvalue_reference<_Dp>::value &&
-                       is_convertible<typename unique_ptr<_Yp, _Dp>::pointer, element_type*>::value,
-                       __nat
-                   >::type = __nat());
-    template <class _Yp, class _Dp>
-        shared_ptr(unique_ptr<_Yp, _Dp>&&,
-                   typename enable_if
-                   <
-                       is_lvalue_reference<_Dp>::value &&
-                       is_convertible<typename unique_ptr<_Yp, _Dp>::pointer, element_type*>::value,
-                       __nat
-                   >::type = __nat());
-
-    ~shared_ptr();
+    template<class _Yp, class _Dp, class = __enable_if_t<__shared_ptr_deleter_ctor_reqs<_Dp, _Yp, element_type>::value> >
+    _LIBCPP_HIDE_FROM_ABI
+    shared_ptr(_Yp* __p, _Dp __d)
+        : __ptr_(__p)
+    {
+#ifndef _LIBCPP_NO_EXCEPTIONS
+        try
+        {
+#endif // _LIBCPP_NO_EXCEPTIONS
+            typedef typename __shared_ptr_default_allocator<_Yp>::type _AllocT;
+            typedef __shared_ptr_pointer<_Yp*, _Dp, _AllocT > _CntrlBlk;
+#ifndef _LIBCPP_CXX03_LANG
+            __cntrl_ = new _CntrlBlk(__p, _VSTD::move(__d), _AllocT());
+#else
+            __cntrl_ = new _CntrlBlk(__p, __d, _AllocT());
+#endif // not _LIBCPP_CXX03_LANG
+            __enable_weak_this(__p, __p);
+#ifndef _LIBCPP_NO_EXCEPTIONS
+        }
+        catch (...)
+        {
+            __d(__p);
+            throw;
+        }
+#endif // _LIBCPP_NO_EXCEPTIONS
+    }
 
-    _LIBCPP_INLINE_VISIBILITY
-    shared_ptr& operator=(const shared_ptr& __r) _NOEXCEPT;
-    template<class _Yp>
-        typename enable_if
-        <
-            __compatible_with<_Yp, _Tp>::value,
-            shared_ptr&
-        >::type
-        _LIBCPP_INLINE_VISIBILITY
-        operator=(const shared_ptr<_Yp>& __r) _NOEXCEPT;
-    _LIBCPP_INLINE_VISIBILITY
-    shared_ptr& operator=(shared_ptr&& __r) _NOEXCEPT;
-    template<class _Yp>
-        typename enable_if
-        <
-            __compatible_with<_Yp, _Tp>::value,
-            shared_ptr&
-        >::type
-        _LIBCPP_INLINE_VISIBILITY
-        operator=(shared_ptr<_Yp>&& __r);
-#if _LIBCPP_STD_VER <= 14 || defined(_LIBCPP_ENABLE_CXX17_REMOVED_AUTO_PTR)
-    template<class _Yp>
-        _LIBCPP_INLINE_VISIBILITY
-        typename enable_if
-        <
-            !is_array<_Yp>::value &&
-            is_convertible<_Yp*, element_type*>::value,
-            shared_ptr
-        >::type&
-        operator=(auto_ptr<_Yp>&& __r);
-#endif
-    template <class _Yp, class _Dp>
-        typename enable_if
-        <
-            is_convertible<typename unique_ptr<_Yp, _Dp>::pointer, element_type*>::value,
-            shared_ptr&
-        >::type
-        _LIBCPP_INLINE_VISIBILITY
-        operator=(unique_ptr<_Yp, _Dp>&& __r);
+    template<class _Yp, class _Dp, class _Alloc, class = __enable_if_t<__shared_ptr_deleter_ctor_reqs<_Dp, _Yp, element_type>::value> >
+    _LIBCPP_HIDE_FROM_ABI
+    shared_ptr(_Yp* __p, _Dp __d, _Alloc __a)
+        : __ptr_(__p)
+    {
+#ifndef _LIBCPP_NO_EXCEPTIONS
+        try
+        {
+#endif // _LIBCPP_NO_EXCEPTIONS
+            typedef __shared_ptr_pointer<_Yp*, _Dp, _Alloc> _CntrlBlk;
+            typedef typename __allocator_traits_rebind<_Alloc, _CntrlBlk>::type _A2;
+            typedef __allocator_destructor<_A2> _D2;
+            _A2 __a2(__a);
+            unique_ptr<_CntrlBlk, _D2> __hold2(__a2.allocate(1), _D2(__a2, 1));
+            ::new ((void*)_VSTD::addressof(*__hold2.get()))
+#ifndef _LIBCPP_CXX03_LANG
+                _CntrlBlk(__p, _VSTD::move(__d), __a);
+#else
+                _CntrlBlk(__p, __d, __a);
+#endif // not _LIBCPP_CXX03_LANG
+            __cntrl_ = _VSTD::addressof(*__hold2.release());
+            __enable_weak_this(__p, __p);
+#ifndef _LIBCPP_NO_EXCEPTIONS
+        }
+        catch (...)
+        {
+            __d(__p);
+            throw;
+        }
+#endif // _LIBCPP_NO_EXCEPTIONS
+    }
+
+    template<class _Dp>
+    _LIBCPP_HIDE_FROM_ABI
+    shared_ptr(nullptr_t __p, _Dp __d)
+        : __ptr_(nullptr)
+    {
+#ifndef _LIBCPP_NO_EXCEPTIONS
+        try
+        {
+#endif // _LIBCPP_NO_EXCEPTIONS
+            typedef typename __shared_ptr_default_allocator<_Tp>::type _AllocT;
+            typedef __shared_ptr_pointer<nullptr_t, _Dp, _AllocT > _CntrlBlk;
+#ifndef _LIBCPP_CXX03_LANG
+            __cntrl_ = new _CntrlBlk(__p, _VSTD::move(__d), _AllocT());
+#else
+            __cntrl_ = new _CntrlBlk(__p, __d, _AllocT());
+#endif // not _LIBCPP_CXX03_LANG
+#ifndef _LIBCPP_NO_EXCEPTIONS
+        }
+        catch (...)
+        {
+            __d(__p);
+            throw;
+        }
+#endif // _LIBCPP_NO_EXCEPTIONS
+    }
+
+    template<class _Dp, class _Alloc>
+    _LIBCPP_HIDE_FROM_ABI
+    shared_ptr(nullptr_t __p, _Dp __d, _Alloc __a)
+        : __ptr_(nullptr)
+    {
+#ifndef _LIBCPP_NO_EXCEPTIONS
+        try
+        {
+#endif // _LIBCPP_NO_EXCEPTIONS
+            typedef __shared_ptr_pointer<nullptr_t, _Dp, _Alloc> _CntrlBlk;
+            typedef typename __allocator_traits_rebind<_Alloc, _CntrlBlk>::type _A2;
+            typedef __allocator_destructor<_A2> _D2;
+            _A2 __a2(__a);
+            unique_ptr<_CntrlBlk, _D2> __hold2(__a2.allocate(1), _D2(__a2, 1));
+            ::new ((void*)_VSTD::addressof(*__hold2.get()))
+#ifndef _LIBCPP_CXX03_LANG
+                _CntrlBlk(__p, _VSTD::move(__d), __a);
+#else
+                _CntrlBlk(__p, __d, __a);
+#endif // not _LIBCPP_CXX03_LANG
+            __cntrl_ = _VSTD::addressof(*__hold2.release());
+#ifndef _LIBCPP_NO_EXCEPTIONS
+        }
+        catch (...)
+        {
+            __d(__p);
+            throw;
+        }
+#endif // _LIBCPP_NO_EXCEPTIONS
+    }
 
-    _LIBCPP_INLINE_VISIBILITY
-    void swap(shared_ptr& __r) _NOEXCEPT;
-    _LIBCPP_INLINE_VISIBILITY
-    void reset() _NOEXCEPT;
     template<class _Yp>
-        typename enable_if
-        <
-            __compatible_with<_Yp, _Tp>::value,
-            void
-        >::type
-        _LIBCPP_INLINE_VISIBILITY
-        reset(_Yp* __p);
-    template<class _Yp, class _Dp>
-        typename enable_if
-        <
-            __compatible_with<_Yp, _Tp>::value,
-            void
-        >::type
-        _LIBCPP_INLINE_VISIBILITY
-        reset(_Yp* __p, _Dp __d);
-    template<class _Yp, class _Dp, class _Alloc>
-        typename enable_if
-        <
-            __compatible_with<_Yp, _Tp>::value,
-            void
-        >::type
-        _LIBCPP_INLINE_VISIBILITY
-        reset(_Yp* __p, _Dp __d, _Alloc __a);
+    _LIBCPP_HIDE_FROM_ABI
+    shared_ptr(const shared_ptr<_Yp>& __r, element_type *__p) _NOEXCEPT
+        : __ptr_(__p),
+          __cntrl_(__r.__cntrl_)
+    {
+        if (__cntrl_)
+            __cntrl_->__add_shared();
+    }
 
-    _LIBCPP_INLINE_VISIBILITY
-    element_type* get() const _NOEXCEPT {return __ptr_;}
-    _LIBCPP_INLINE_VISIBILITY
-    typename add_lvalue_reference<element_type>::type operator*() const _NOEXCEPT
-        {return *__ptr_;}
-    _LIBCPP_INLINE_VISIBILITY
-    element_type* operator->() const _NOEXCEPT
+    _LIBCPP_HIDE_FROM_ABI
+    shared_ptr(const shared_ptr& __r) _NOEXCEPT
+        : __ptr_(__r.__ptr_),
+          __cntrl_(__r.__cntrl_)
     {
-        static_assert(!is_array<_Tp>::value,
-                      "std::shared_ptr<T>::operator-> is only valid when T is not an array type.");
-        return __ptr_;
+        if (__cntrl_)
+            __cntrl_->__add_shared();
     }
-    _LIBCPP_INLINE_VISIBILITY
-    long use_count() const _NOEXCEPT {return __cntrl_ ? __cntrl_->use_count() : 0;}
-    _LIBCPP_INLINE_VISIBILITY
-    bool unique() const _NOEXCEPT {return use_count() == 1;}
-    _LIBCPP_INLINE_VISIBILITY
-    explicit operator bool() const _NOEXCEPT {return get() != nullptr;}
-    template <class _Up>
-        _LIBCPP_INLINE_VISIBILITY
-        bool owner_before(shared_ptr<_Up> const& __p) const _NOEXCEPT
-        {return __cntrl_ < __p.__cntrl_;}
-    template <class _Up>
-        _LIBCPP_INLINE_VISIBILITY
-        bool owner_before(weak_ptr<_Up> const& __p) const _NOEXCEPT
-        {return __cntrl_ < __p.__cntrl_;}
-    _LIBCPP_INLINE_VISIBILITY
-    bool
-    __owner_equivalent(const shared_ptr& __p) const
-        {return __cntrl_ == __p.__cntrl_;}
 
-#if _LIBCPP_STD_VER > 14
-    typename add_lvalue_reference<element_type>::type
-    _LIBCPP_INLINE_VISIBILITY
-    operator[](ptrdiff_t __i) const
+    template<class _Yp, class = __enable_if_t<__compatible_with<_Yp, _Tp>::value> >
+    _LIBCPP_HIDE_FROM_ABI
+    shared_ptr(const shared_ptr<_Yp>& __r) _NOEXCEPT
+        : __ptr_(__r.__ptr_),
+          __cntrl_(__r.__cntrl_)
     {
-            static_assert(is_array<_Tp>::value,
-                          "std::shared_ptr<T>::operator[] is only valid when T is an array type.");
-            return __ptr_[__i];
+        if (__cntrl_)
+            __cntrl_->__add_shared();
     }
-#endif
 
-#ifndef _LIBCPP_NO_RTTI
-    template <class _Dp>
-        _LIBCPP_INLINE_VISIBILITY
-        _Dp* __get_deleter() const _NOEXCEPT
-            {return static_cast<_Dp*>(__cntrl_
-                    ? const_cast<void *>(__cntrl_->__get_deleter(typeid(_Dp)))
-                      : nullptr);}
-#endif // _LIBCPP_NO_RTTI
+    _LIBCPP_HIDE_FROM_ABI
+    shared_ptr(shared_ptr&& __r) _NOEXCEPT
+        : __ptr_(__r.__ptr_),
+          __cntrl_(__r.__cntrl_)
+    {
+        __r.__ptr_ = nullptr;
+        __r.__cntrl_ = nullptr;
+    }
 
-    template<class _Yp, class _CntrlBlk>
-    static shared_ptr<_Tp>
-    __create_with_control_block(_Yp* __p, _CntrlBlk* __cntrl) _NOEXCEPT
+    template<class _Yp, class = __enable_if_t<__compatible_with<_Yp, _Tp>::value> >
+    _LIBCPP_HIDE_FROM_ABI
+    shared_ptr(shared_ptr<_Yp>&& __r) _NOEXCEPT
+        : __ptr_(__r.__ptr_),
+          __cntrl_(__r.__cntrl_)
     {
-        shared_ptr<_Tp> __r;
-        __r.__ptr_ = __p;
-        __r.__cntrl_ = __cntrl;
-        __r.__enable_weak_this(__r.__ptr_, __r.__ptr_);
-        return __r;
+        __r.__ptr_ = nullptr;
+        __r.__cntrl_ = nullptr;
     }
 
-private:
-    template <class _Yp, bool = is_function<_Yp>::value>
-        struct __shared_ptr_default_allocator
-        {
-            typedef allocator<_Yp> type;
-        };
+    template<class _Yp, class = __enable_if_t<__compatible_with<_Yp, _Tp>::value> >
+    _LIBCPP_HIDE_FROM_ABI
+    explicit shared_ptr(const weak_ptr<_Yp>& __r)
+        : __ptr_(__r.__ptr_),
+          __cntrl_(__r.__cntrl_ ? __r.__cntrl_->lock() : __r.__cntrl_)
+    {
+        if (__cntrl_ == nullptr)
+            __throw_bad_weak_ptr();
+    }
 
-    template <class _Yp>
-        struct __shared_ptr_default_allocator<_Yp, true>
+#if _LIBCPP_STD_VER <= 14 || defined(_LIBCPP_ENABLE_CXX17_REMOVED_AUTO_PTR)
+    template<class _Yp, class = __enable_if_t<is_convertible<_Yp*, element_type*>::value> >
+    _LIBCPP_HIDE_FROM_ABI
+    shared_ptr(auto_ptr<_Yp>&& __r)
+        : __ptr_(__r.get())
+    {
+        typedef __shared_ptr_pointer<_Yp*, default_delete<_Yp>, allocator<_Yp> > _CntrlBlk;
+        __cntrl_ = new _CntrlBlk(__r.get(), default_delete<_Yp>(), allocator<_Yp>());
+        __enable_weak_this(__r.get(), __r.get());
+        __r.release();
+    }
+#endif
+
+    template <class _Yp, class _Dp, __enable_if_t<
+        !is_lvalue_reference<_Dp>::value &&
+         is_convertible<typename unique_ptr<_Yp, _Dp>::pointer, element_type*>::value
+    >* = nullptr>
+    _LIBCPP_HIDE_FROM_ABI
+    shared_ptr(unique_ptr<_Yp, _Dp>&& __r)
+        : __ptr_(__r.get())
+    {
+#if _LIBCPP_STD_VER > 11
+        if (__ptr_ == nullptr)
+            __cntrl_ = nullptr;
+        else
+#endif
         {
-            typedef allocator<__shared_ptr_dummy_rebind_allocator_type> type;
-        };
+            typedef typename __shared_ptr_default_allocator<_Yp>::type _AllocT;
+            typedef __shared_ptr_pointer<typename unique_ptr<_Yp, _Dp>::pointer, _Dp, _AllocT > _CntrlBlk;
+            __cntrl_ = new _CntrlBlk(__r.get(), __r.get_deleter(), _AllocT());
+            __enable_weak_this(__r.get(), __r.get());
+        }
+        __r.release();
+    }
 
-    template <class _Yp, class _OrigPtr>
-        _LIBCPP_INLINE_VISIBILITY
-        typename enable_if<is_convertible<_OrigPtr*,
-                                          const enable_shared_from_this<_Yp>*
-        >::value,
-            void>::type
-        __enable_weak_this(const enable_shared_from_this<_Yp>* __e,
-                           _OrigPtr* __ptr) _NOEXCEPT
+    template <class _Yp, class _Dp, __enable_if_t<
+        is_lvalue_reference<_Dp>::value &&
+        is_convertible<typename unique_ptr<_Yp, _Dp>::pointer, element_type*>::value
+    >* = nullptr>
+    _LIBCPP_HIDE_FROM_ABI
+    shared_ptr(unique_ptr<_Yp, _Dp>&& __r)
+        : __ptr_(__r.get())
+    {
+#if _LIBCPP_STD_VER > 11
+        if (__ptr_ == nullptr)
+            __cntrl_ = nullptr;
+        else
+#endif
         {
-            typedef typename remove_cv<_Yp>::type _RawYp;
-            if (__e && __e->__weak_this_.expired())
-            {
-                __e->__weak_this_ = shared_ptr<_RawYp>(*this,
-                    const_cast<_RawYp*>(static_cast<const _Yp*>(__ptr)));
-            }
+            typedef typename __shared_ptr_default_allocator<_Yp>::type _AllocT;
+            typedef __shared_ptr_pointer<typename unique_ptr<_Yp, _Dp>::pointer,
+                                        reference_wrapper<typename remove_reference<_Dp>::type>,
+                                        _AllocT > _CntrlBlk;
+            __cntrl_ = new _CntrlBlk(__r.get(), _VSTD::ref(__r.get_deleter()), _AllocT());
+            __enable_weak_this(__r.get(), __r.get());
         }
+        __r.release();
+    }
 
-    _LIBCPP_INLINE_VISIBILITY void __enable_weak_this(...) _NOEXCEPT {}
+    _LIBCPP_HIDE_FROM_ABI
+    ~shared_ptr()
+    {
+        if (__cntrl_)
+            __cntrl_->__release_shared();
+    }
 
-    template <class, class _Yp>
-        struct __shared_ptr_default_delete
-            : default_delete<_Yp> {};
+    _LIBCPP_HIDE_FROM_ABI
+    shared_ptr<_Tp>& operator=(const shared_ptr& __r) _NOEXCEPT
+    {
+        shared_ptr(__r).swap(*this);
+        return *this;
+    }
 
-    template <class _Yp, class _Un, size_t _Sz>
-        struct __shared_ptr_default_delete<_Yp[_Sz], _Un>
-            : default_delete<_Yp[]> {};
+    template<class _Yp, class = __enable_if_t<__compatible_with<_Yp, _Tp>::value> >
+    _LIBCPP_HIDE_FROM_ABI
+    shared_ptr<_Tp>& operator=(const shared_ptr<_Yp>& __r) _NOEXCEPT
+    {
+        shared_ptr(__r).swap(*this);
+        return *this;
+    }
 
-    template <class _Yp, class _Un>
-        struct __shared_ptr_default_delete<_Yp[], _Un>
-            : default_delete<_Yp[]> {};
+    _LIBCPP_HIDE_FROM_ABI
+    shared_ptr<_Tp>& operator=(shared_ptr&& __r) _NOEXCEPT
+    {
+        shared_ptr(_VSTD::move(__r)).swap(*this);
+        return *this;
+    }
 
-    template <class _Up> friend class _LIBCPP_TEMPLATE_VIS shared_ptr;
-    template <class _Up> friend class _LIBCPP_TEMPLATE_VIS weak_ptr;
-};
+    template<class _Yp, class = __enable_if_t<__compatible_with<_Yp, _Tp>::value> >
+    _LIBCPP_HIDE_FROM_ABI
+    shared_ptr<_Tp>& operator=(shared_ptr<_Yp>&& __r)
+    {
+        shared_ptr(_VSTD::move(__r)).swap(*this);
+        return *this;
+    }
 
-#if _LIBCPP_STD_VER > 14
-template<class _Tp>
-shared_ptr(weak_ptr<_Tp>) -> shared_ptr<_Tp>;
-template<class _Tp, class _Dp>
-shared_ptr(unique_ptr<_Tp, _Dp>) -> shared_ptr<_Tp>;
+#if _LIBCPP_STD_VER <= 14 || defined(_LIBCPP_ENABLE_CXX17_REMOVED_AUTO_PTR)
+    template<class _Yp, class = __enable_if_t<
+        !is_array<_Yp>::value &&
+        is_convertible<_Yp*, typename shared_ptr<_Tp>::element_type*>::value
+    > >
+    _LIBCPP_HIDE_FROM_ABI
+    shared_ptr<_Tp>& operator=(auto_ptr<_Yp>&& __r)
+    {
+        shared_ptr(_VSTD::move(__r)).swap(*this);
+        return *this;
+    }
 #endif
 
-template<class _Tp>
-inline
-_LIBCPP_CONSTEXPR
-shared_ptr<_Tp>::shared_ptr() _NOEXCEPT
-    : __ptr_(nullptr),
-      __cntrl_(nullptr)
-{
-}
-
-template<class _Tp>
-inline
-_LIBCPP_CONSTEXPR
-shared_ptr<_Tp>::shared_ptr(nullptr_t) _NOEXCEPT
-    : __ptr_(nullptr),
-      __cntrl_(nullptr)
-{
-}
+    template <class _Yp, class _Dp, class = __enable_if_t<
+        is_convertible<typename unique_ptr<_Yp, _Dp>::pointer, element_type*>::value
+    > >
+    _LIBCPP_HIDE_FROM_ABI
+    shared_ptr<_Tp>& operator=(unique_ptr<_Yp, _Dp>&& __r)
+    {
+        shared_ptr(_VSTD::move(__r)).swap(*this);
+        return *this;
+    }
 
-template<class _Tp>
-template<class _Yp, class _Dp>
-shared_ptr<_Tp>::shared_ptr(_Yp* __p, _Dp __d,
-                            typename enable_if<__shared_ptr_deleter_ctor_reqs<_Dp, _Yp, element_type>::value, __nat>::type)
-    : __ptr_(__p)
-{
-#ifndef _LIBCPP_NO_EXCEPTIONS
-    try
+    _LIBCPP_HIDE_FROM_ABI
+    void swap(shared_ptr& __r) _NOEXCEPT
     {
-#endif // _LIBCPP_NO_EXCEPTIONS
-        typedef typename __shared_ptr_default_allocator<_Yp>::type _AllocT;
-        typedef __shared_ptr_pointer<_Yp*, _Dp, _AllocT > _CntrlBlk;
-#ifndef _LIBCPP_CXX03_LANG
-        __cntrl_ = new _CntrlBlk(__p, _VSTD::move(__d), _AllocT());
-#else
-        __cntrl_ = new _CntrlBlk(__p, __d, _AllocT());
-#endif // not _LIBCPP_CXX03_LANG
-        __enable_weak_this(__p, __p);
-#ifndef _LIBCPP_NO_EXCEPTIONS
+        _VSTD::swap(__ptr_, __r.__ptr_);
+        _VSTD::swap(__cntrl_, __r.__cntrl_);
     }
-    catch (...)
+
+    _LIBCPP_HIDE_FROM_ABI
+    void reset() _NOEXCEPT
     {
-        __d(__p);
-        throw;
+        shared_ptr().swap(*this);
     }
-#endif // _LIBCPP_NO_EXCEPTIONS
-}
 
-template<class _Tp>
-template<class _Dp>
-shared_ptr<_Tp>::shared_ptr(nullptr_t __p, _Dp __d)
-    : __ptr_(nullptr)
-{
-#ifndef _LIBCPP_NO_EXCEPTIONS
-    try
+    template<class _Yp, class = __enable_if_t<
+        __compatible_with<_Yp, _Tp>::value
+    > >
+    _LIBCPP_HIDE_FROM_ABI
+    void reset(_Yp* __p)
     {
-#endif // _LIBCPP_NO_EXCEPTIONS
-        typedef typename __shared_ptr_default_allocator<_Tp>::type _AllocT;
-        typedef __shared_ptr_pointer<nullptr_t, _Dp, _AllocT > _CntrlBlk;
-#ifndef _LIBCPP_CXX03_LANG
-        __cntrl_ = new _CntrlBlk(__p, _VSTD::move(__d), _AllocT());
-#else
-        __cntrl_ = new _CntrlBlk(__p, __d, _AllocT());
-#endif // not _LIBCPP_CXX03_LANG
-#ifndef _LIBCPP_NO_EXCEPTIONS
+        shared_ptr(__p).swap(*this);
+    }
+
+    template<class _Yp, class _Dp, class = __enable_if_t<
+        __compatible_with<_Yp, _Tp>::value
+    > >
+    _LIBCPP_HIDE_FROM_ABI
+    void reset(_Yp* __p, _Dp __d)
+    {
+        shared_ptr(__p, __d).swap(*this);
     }
-    catch (...)
+
+    template<class _Yp, class _Dp, class _Alloc, class = __enable_if_t<
+        __compatible_with<_Yp, _Tp>::value
+    > >
+    _LIBCPP_HIDE_FROM_ABI
+    void reset(_Yp* __p, _Dp __d, _Alloc __a)
     {
-        __d(__p);
-        throw;
+        shared_ptr(__p, __d, __a).swap(*this);
     }
-#endif // _LIBCPP_NO_EXCEPTIONS
-}
 
-template<class _Tp>
-template<class _Yp, class _Dp, class _Alloc>
-shared_ptr<_Tp>::shared_ptr(_Yp* __p, _Dp __d, _Alloc __a,
-                            typename enable_if<__shared_ptr_deleter_ctor_reqs<_Dp, _Yp, element_type>::value, __nat>::type)
-    : __ptr_(__p)
-{
-#ifndef _LIBCPP_NO_EXCEPTIONS
-    try
+    _LIBCPP_HIDE_FROM_ABI
+    element_type* get() const _NOEXCEPT
     {
-#endif // _LIBCPP_NO_EXCEPTIONS
-        typedef __shared_ptr_pointer<_Yp*, _Dp, _Alloc> _CntrlBlk;
-        typedef typename __allocator_traits_rebind<_Alloc, _CntrlBlk>::type _A2;
-        typedef __allocator_destructor<_A2> _D2;
-        _A2 __a2(__a);
-        unique_ptr<_CntrlBlk, _D2> __hold2(__a2.allocate(1), _D2(__a2, 1));
-        ::new ((void*)_VSTD::addressof(*__hold2.get()))
-#ifndef _LIBCPP_CXX03_LANG
-            _CntrlBlk(__p, _VSTD::move(__d), __a);
-#else
-            _CntrlBlk(__p, __d, __a);
-#endif // not _LIBCPP_CXX03_LANG
-        __cntrl_ = _VSTD::addressof(*__hold2.release());
-        __enable_weak_this(__p, __p);
-#ifndef _LIBCPP_NO_EXCEPTIONS
+        return __ptr_;
     }
-    catch (...)
+
+    _LIBCPP_HIDE_FROM_ABI
+    typename add_lvalue_reference<element_type>::type operator*() const _NOEXCEPT
     {
-        __d(__p);
-        throw;
+        return *__ptr_;
     }
-#endif // _LIBCPP_NO_EXCEPTIONS
-}
 
-template<class _Tp>
-template<class _Dp, class _Alloc>
-shared_ptr<_Tp>::shared_ptr(nullptr_t __p, _Dp __d, _Alloc __a)
-    : __ptr_(nullptr)
-{
-#ifndef _LIBCPP_NO_EXCEPTIONS
-    try
+    _LIBCPP_HIDE_FROM_ABI
+    element_type* operator->() const _NOEXCEPT
     {
-#endif // _LIBCPP_NO_EXCEPTIONS
-        typedef __shared_ptr_pointer<nullptr_t, _Dp, _Alloc> _CntrlBlk;
-        typedef typename __allocator_traits_rebind<_Alloc, _CntrlBlk>::type _A2;
-        typedef __allocator_destructor<_A2> _D2;
-        _A2 __a2(__a);
-        unique_ptr<_CntrlBlk, _D2> __hold2(__a2.allocate(1), _D2(__a2, 1));
-        ::new ((void*)_VSTD::addressof(*__hold2.get()))
-#ifndef _LIBCPP_CXX03_LANG
-            _CntrlBlk(__p, _VSTD::move(__d), __a);
-#else
-            _CntrlBlk(__p, __d, __a);
-#endif // not _LIBCPP_CXX03_LANG
-        __cntrl_ = _VSTD::addressof(*__hold2.release());
-#ifndef _LIBCPP_NO_EXCEPTIONS
+        static_assert(!is_array<_Tp>::value,
+                      "std::shared_ptr<T>::operator-> is only valid when T is not an array type.");
+        return __ptr_;
     }
-    catch (...)
+
+    _LIBCPP_HIDE_FROM_ABI
+    long use_count() const _NOEXCEPT
     {
-        __d(__p);
-        throw;
+        return __cntrl_ ? __cntrl_->use_count() : 0;
     }
-#endif // _LIBCPP_NO_EXCEPTIONS
-}
 
-template<class _Tp>
-template<class _Yp>
-inline
-shared_ptr<_Tp>::shared_ptr(const shared_ptr<_Yp>& __r, element_type *__p) _NOEXCEPT
-    : __ptr_(__p),
-      __cntrl_(__r.__cntrl_)
-{
-    if (__cntrl_)
-        __cntrl_->__add_shared();
-}
+    _LIBCPP_HIDE_FROM_ABI
+    bool unique() const _NOEXCEPT
+    {
+        return use_count() == 1;
+    }
 
-template<class _Tp>
-inline
-shared_ptr<_Tp>::shared_ptr(const shared_ptr& __r) _NOEXCEPT
-    : __ptr_(__r.__ptr_),
-      __cntrl_(__r.__cntrl_)
-{
-    if (__cntrl_)
-        __cntrl_->__add_shared();
-}
+    _LIBCPP_HIDE_FROM_ABI
+    explicit operator bool() const _NOEXCEPT
+    {
+        return get() != nullptr;
+    }
 
-template<class _Tp>
-template<class _Yp>
-inline
-shared_ptr<_Tp>::shared_ptr(const shared_ptr<_Yp>& __r,
-                            typename enable_if<__compatible_with<_Yp, _Tp>::value, __nat>::type)
-         _NOEXCEPT
-    : __ptr_(__r.__ptr_),
-      __cntrl_(__r.__cntrl_)
-{
-    if (__cntrl_)
-        __cntrl_->__add_shared();
-}
+    template <class _Up>
+    _LIBCPP_HIDE_FROM_ABI
+    bool owner_before(shared_ptr<_Up> const& __p) const _NOEXCEPT
+    {
+        return __cntrl_ < __p.__cntrl_;
+    }
 
-template<class _Tp>
-inline
-shared_ptr<_Tp>::shared_ptr(shared_ptr&& __r) _NOEXCEPT
-    : __ptr_(__r.__ptr_),
-      __cntrl_(__r.__cntrl_)
-{
-    __r.__ptr_ = nullptr;
-    __r.__cntrl_ = nullptr;
-}
+    template <class _Up>
+    _LIBCPP_HIDE_FROM_ABI
+    bool owner_before(weak_ptr<_Up> const& __p) const _NOEXCEPT
+    {
+        return __cntrl_ < __p.__cntrl_;
+    }
 
-template<class _Tp>
-template<class _Yp>
-inline
-shared_ptr<_Tp>::shared_ptr(shared_ptr<_Yp>&& __r,
-                            typename enable_if<__compatible_with<_Yp, _Tp>::value, __nat>::type)
-         _NOEXCEPT
-    : __ptr_(__r.__ptr_),
-      __cntrl_(__r.__cntrl_)
-{
-    __r.__ptr_ = nullptr;
-    __r.__cntrl_ = nullptr;
-}
+    _LIBCPP_HIDE_FROM_ABI
+    bool __owner_equivalent(const shared_ptr& __p) const
+    {
+        return __cntrl_ == __p.__cntrl_;
+    }
 
-#if _LIBCPP_STD_VER <= 14 || defined(_LIBCPP_ENABLE_CXX17_REMOVED_AUTO_PTR)
-template<class _Tp>
-template<class _Yp>
-shared_ptr<_Tp>::shared_ptr(auto_ptr<_Yp>&& __r,
-                            typename enable_if<is_convertible<_Yp*, element_type*>::value, __nat>::type)
-    : __ptr_(__r.get())
-{
-    typedef __shared_ptr_pointer<_Yp*, default_delete<_Yp>, allocator<_Yp> > _CntrlBlk;
-    __cntrl_ = new _CntrlBlk(__r.get(), default_delete<_Yp>(), allocator<_Yp>());
-    __enable_weak_this(__r.get(), __r.get());
-    __r.release();
-}
+#if _LIBCPP_STD_VER > 14
+    _LIBCPP_HIDE_FROM_ABI
+    typename add_lvalue_reference<element_type>::type operator[](ptrdiff_t __i) const
+    {
+            static_assert(is_array<_Tp>::value,
+                          "std::shared_ptr<T>::operator[] is only valid when T is an array type.");
+            return __ptr_[__i];
+    }
 #endif
 
-template<class _Tp>
-template <class _Yp, class _Dp>
-shared_ptr<_Tp>::shared_ptr(unique_ptr<_Yp, _Dp>&& __r,
-                            typename enable_if
-                            <
-                                !is_lvalue_reference<_Dp>::value &&
-                                is_convertible<typename unique_ptr<_Yp, _Dp>::pointer, element_type*>::value,
-                                __nat
-                            >::type)
-    : __ptr_(__r.get())
-{
-#if _LIBCPP_STD_VER > 11
-    if (__ptr_ == nullptr)
-        __cntrl_ = nullptr;
-    else
-#endif
+#ifndef _LIBCPP_NO_RTTI
+    template <class _Dp>
+    _LIBCPP_HIDE_FROM_ABI
+    _Dp* __get_deleter() const _NOEXCEPT
     {
-        typedef typename __shared_ptr_default_allocator<_Yp>::type _AllocT;
-        typedef __shared_ptr_pointer<typename unique_ptr<_Yp, _Dp>::pointer, _Dp, _AllocT > _CntrlBlk;
-        __cntrl_ = new _CntrlBlk(__r.get(), __r.get_deleter(), _AllocT());
-        __enable_weak_this(__r.get(), __r.get());
+        return static_cast<_Dp*>(__cntrl_
+                    ? const_cast<void *>(__cntrl_->__get_deleter(typeid(_Dp)))
+                      : nullptr);
     }
-    __r.release();
-}
+#endif // _LIBCPP_NO_RTTI
 
-template<class _Tp>
-template <class _Yp, class _Dp>
-shared_ptr<_Tp>::shared_ptr(unique_ptr<_Yp, _Dp>&& __r,
-                            typename enable_if
-                            <
-                                is_lvalue_reference<_Dp>::value &&
-                                is_convertible<typename unique_ptr<_Yp, _Dp>::pointer, element_type*>::value,
-                                __nat
-                            >::type)
-    : __ptr_(__r.get())
-{
-#if _LIBCPP_STD_VER > 11
-    if (__ptr_ == nullptr)
-        __cntrl_ = nullptr;
-    else
-#endif
+    template<class _Yp, class _CntrlBlk>
+    _LIBCPP_HIDE_FROM_ABI
+    static shared_ptr<_Tp> __create_with_control_block(_Yp* __p, _CntrlBlk* __cntrl) _NOEXCEPT
     {
-        typedef typename __shared_ptr_default_allocator<_Yp>::type _AllocT;
-        typedef __shared_ptr_pointer<typename unique_ptr<_Yp, _Dp>::pointer,
-                                     reference_wrapper<typename remove_reference<_Dp>::type>,
-                                     _AllocT > _CntrlBlk;
-        __cntrl_ = new _CntrlBlk(__r.get(), _VSTD::ref(__r.get_deleter()), _AllocT());
-        __enable_weak_this(__r.get(), __r.get());
+        shared_ptr<_Tp> __r;
+        __r.__ptr_ = __p;
+        __r.__cntrl_ = __cntrl;
+        __r.__enable_weak_this(__r.__ptr_, __r.__ptr_);
+        return __r;
     }
-    __r.release();
-}
-
-template<class _Tp>
-shared_ptr<_Tp>::~shared_ptr()
-{
-    if (__cntrl_)
-        __cntrl_->__release_shared();
-}
-
-template<class _Tp>
-inline
-shared_ptr<_Tp>&
-shared_ptr<_Tp>::operator=(const shared_ptr& __r) _NOEXCEPT
-{
-    shared_ptr(__r).swap(*this);
-    return *this;
-}
-
-template<class _Tp>
-template<class _Yp>
-inline
-typename enable_if
-<
-    __compatible_with<_Yp, _Tp>::value,
-    shared_ptr<_Tp>&
->::type
-shared_ptr<_Tp>::operator=(const shared_ptr<_Yp>& __r) _NOEXCEPT
-{
-    shared_ptr(__r).swap(*this);
-    return *this;
-}
 
-template<class _Tp>
-inline
-shared_ptr<_Tp>&
-shared_ptr<_Tp>::operator=(shared_ptr&& __r) _NOEXCEPT
-{
-    shared_ptr(_VSTD::move(__r)).swap(*this);
-    return *this;
-}
+private:
+    template <class _Yp, bool = is_function<_Yp>::value>
+    struct __shared_ptr_default_allocator
+    {
+        typedef allocator<_Yp> type;
+    };
 
-template<class _Tp>
-template<class _Yp>
-inline
-typename enable_if
-<
-    __compatible_with<_Yp, _Tp>::value,
-    shared_ptr<_Tp>&
->::type
-shared_ptr<_Tp>::operator=(shared_ptr<_Yp>&& __r)
-{
-    shared_ptr(_VSTD::move(__r)).swap(*this);
-    return *this;
-}
+    template <class _Yp>
+    struct __shared_ptr_default_allocator<_Yp, true>
+    {
+        typedef allocator<__shared_ptr_dummy_rebind_allocator_type> type;
+    };
 
-#if _LIBCPP_STD_VER <= 14 || defined(_LIBCPP_ENABLE_CXX17_REMOVED_AUTO_PTR)
-template<class _Tp>
-template<class _Yp>
-inline
-typename enable_if
-<
-    !is_array<_Yp>::value &&
-    is_convertible<_Yp*, typename shared_ptr<_Tp>::element_type*>::value,
-    shared_ptr<_Tp>
->::type&
-shared_ptr<_Tp>::operator=(auto_ptr<_Yp>&& __r)
-{
-    shared_ptr(_VSTD::move(__r)).swap(*this);
-    return *this;
-}
-#endif
+    template <class _Yp, class _OrigPtr, class = __enable_if_t<
+        is_convertible<_OrigPtr*, const enable_shared_from_this<_Yp>*>::value
+    > >
+    _LIBCPP_HIDE_FROM_ABI
+    void __enable_weak_this(const enable_shared_from_this<_Yp>* __e, _OrigPtr* __ptr) _NOEXCEPT
+    {
+        typedef typename remove_cv<_Yp>::type _RawYp;
+        if (__e && __e->__weak_this_.expired())
+        {
+            __e->__weak_this_ = shared_ptr<_RawYp>(*this,
+                const_cast<_RawYp*>(static_cast<const _Yp*>(__ptr)));
+        }
+    }
 
-template<class _Tp>
-template <class _Yp, class _Dp>
-inline
-typename enable_if
-<
-    is_convertible<typename unique_ptr<_Yp, _Dp>::pointer,
-                   typename shared_ptr<_Tp>::element_type*>::value,
-    shared_ptr<_Tp>&
->::type
-shared_ptr<_Tp>::operator=(unique_ptr<_Yp, _Dp>&& __r)
-{
-    shared_ptr(_VSTD::move(__r)).swap(*this);
-    return *this;
-}
+    _LIBCPP_HIDE_FROM_ABI void __enable_weak_this(...) _NOEXCEPT { }
 
-template<class _Tp>
-inline
-void
-shared_ptr<_Tp>::swap(shared_ptr& __r) _NOEXCEPT
-{
-    _VSTD::swap(__ptr_, __r.__ptr_);
-    _VSTD::swap(__cntrl_, __r.__cntrl_);
-}
+    template <class, class _Yp>
+    struct __shared_ptr_default_delete
+        : default_delete<_Yp>
+    { };
 
-template<class _Tp>
-inline
-void
-shared_ptr<_Tp>::reset() _NOEXCEPT
-{
-    shared_ptr().swap(*this);
-}
+    template <class _Yp, class _Un, size_t _Sz>
+    struct __shared_ptr_default_delete<_Yp[_Sz], _Un>
+        : default_delete<_Yp[]>
+    { };
 
-template<class _Tp>
-template<class _Yp>
-inline
-typename enable_if
-<
-    __compatible_with<_Yp, _Tp>::value,
-    void
->::type
-shared_ptr<_Tp>::reset(_Yp* __p)
-{
-    shared_ptr(__p).swap(*this);
-}
+    template <class _Yp, class _Un>
+    struct __shared_ptr_default_delete<_Yp[], _Un>
+        : default_delete<_Yp[]>
+    { };
 
-template<class _Tp>
-template<class _Yp, class _Dp>
-inline
-typename enable_if
-<
-    __compatible_with<_Yp, _Tp>::value,
-    void
->::type
-shared_ptr<_Tp>::reset(_Yp* __p, _Dp __d)
-{
-    shared_ptr(__p, __d).swap(*this);
-}
+    template <class _Up> friend class _LIBCPP_TEMPLATE_VIS shared_ptr;
+    template <class _Up> friend class _LIBCPP_TEMPLATE_VIS weak_ptr;
+};
 
+#if _LIBCPP_STD_VER > 14
 template<class _Tp>
-template<class _Yp, class _Dp, class _Alloc>
-inline
-typename enable_if
-<
-    __compatible_with<_Yp, _Tp>::value,
-    void
->::type
-shared_ptr<_Tp>::reset(_Yp* __p, _Dp __d, _Alloc __a)
-{
-    shared_ptr(__p, __d, __a).swap(*this);
-}
+shared_ptr(weak_ptr<_Tp>) -> shared_ptr<_Tp>;
+template<class _Tp, class _Dp>
+shared_ptr(unique_ptr<_Tp, _Dp>) -> shared_ptr<_Tp>;
+#endif
 
 //
 // std::allocate_shared and std::make_shared
@@ -1573,17 +1425,6 @@
     weak_ptr().swap(*this);
 }
 
-template<class _Tp>
-template<class _Yp>
-shared_ptr<_Tp>::shared_ptr(const weak_ptr<_Yp>& __r,
-                            typename enable_if<__compatible_with<_Yp, _Tp>::value, __nat>::type)
-    : __ptr_(__r.__ptr_),
-      __cntrl_(__r.__cntrl_ ? __r.__cntrl_->lock() : __r.__cntrl_)
-{
-    if (__cntrl_ == nullptr)
-        __throw_bad_weak_ptr();
-}
-
 template<class _Tp>
 shared_ptr<_Tp>
 weak_ptr<_Tp>::lock() const _NOEXCEPT