Index: include/memory
===================================================================
--- include/memory
+++ include/memory
@@ -2096,24 +2096,28 @@
     typedef const typename remove_reference<_T1>::type& _T1_const_reference;
     typedef const typename remove_reference<_T2>::type& _T2_const_reference;
 
-    _LIBCPP_INLINE_VISIBILITY __libcpp_compressed_pair_imp() : __first_(), __second_() {}
-    _LIBCPP_INLINE_VISIBILITY explicit __libcpp_compressed_pair_imp(_T1_param __t1)
+    _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR
+    __libcpp_compressed_pair_imp() : __first_(), __second_() {}
+    _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR
+    explicit __libcpp_compressed_pair_imp(_T1_param __t1)
         : __first_(_VSTD::forward<_T1_param>(__t1)), __second_() {}
-    _LIBCPP_INLINE_VISIBILITY explicit __libcpp_compressed_pair_imp(_T2_param __t2)
+    _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR
+    explicit __libcpp_compressed_pair_imp(_T2_param __t2)
         : __first_(), __second_(_VSTD::forward<_T2_param>(__t2)) {}
-    _LIBCPP_INLINE_VISIBILITY __libcpp_compressed_pair_imp(_T1_param __t1, _T2_param __t2)
+    _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR
+    __libcpp_compressed_pair_imp(_T1_param __t1, _T2_param __t2)
         : __first_(_VSTD::forward<_T1_param>(__t1)), __second_(_VSTD::forward<_T2_param>(__t2)) {}
 
 #if defined(_LIBCPP_HAS_NO_DEFAULTED_FUNCTIONS) && !defined(_LIBCPP_HAS_NO_RVALUE_REFERENCES)
 
-    _LIBCPP_INLINE_VISIBILITY
+    _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR
     __libcpp_compressed_pair_imp(const __libcpp_compressed_pair_imp& __p)
         _NOEXCEPT_(is_nothrow_copy_constructible<_T1>::value &&
                    is_nothrow_copy_constructible<_T2>::value)
         : __first_(__p.first()),
           __second_(__p.second()) {}
 
-    _LIBCPP_INLINE_VISIBILITY
+    _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR
     __libcpp_compressed_pair_imp& operator=(const __libcpp_compressed_pair_imp& __p)
         _NOEXCEPT_(is_nothrow_copy_assignable<_T1>::value &&
                    is_nothrow_copy_assignable<_T2>::value)
@@ -2123,14 +2127,14 @@
             return *this;
         }
 
-    _LIBCPP_INLINE_VISIBILITY
+    _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR
     __libcpp_compressed_pair_imp(__libcpp_compressed_pair_imp&& __p)
         _NOEXCEPT_(is_nothrow_move_constructible<_T1>::value &&
                    is_nothrow_move_constructible<_T2>::value)
         : __first_(_VSTD::forward<_T1>(__p.first())),
           __second_(_VSTD::forward<_T2>(__p.second())) {}
 
-    _LIBCPP_INLINE_VISIBILITY
+    _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR
     __libcpp_compressed_pair_imp& operator=(__libcpp_compressed_pair_imp&& __p)
         _NOEXCEPT_(is_nothrow_move_assignable<_T1>::value &&
                    is_nothrow_move_assignable<_T2>::value)
@@ -2145,7 +2149,7 @@
 #ifndef _LIBCPP_HAS_NO_VARIADICS
 
     template <class... _Args1, class... _Args2, size_t... _I1, size_t... _I2>
-        _LIBCPP_INLINE_VISIBILITY
+        _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR
         __libcpp_compressed_pair_imp(piecewise_construct_t __pc,
                                      tuple<_Args1...> __first_args,
                                      tuple<_Args2...> __second_args,
@@ -2189,23 +2193,27 @@
     typedef const _T1&                                        _T1_const_reference;
     typedef const typename remove_reference<_T2>::type& _T2_const_reference;
 
-    _LIBCPP_INLINE_VISIBILITY __libcpp_compressed_pair_imp() : __second_() {}
-    _LIBCPP_INLINE_VISIBILITY explicit __libcpp_compressed_pair_imp(_T1_param __t1)
+    _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR
+    __libcpp_compressed_pair_imp() : __second_() {}
+    _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR
+    explicit __libcpp_compressed_pair_imp(_T1_param __t1)
         : _T1(_VSTD::forward<_T1_param>(__t1)), __second_() {}
-    _LIBCPP_INLINE_VISIBILITY explicit __libcpp_compressed_pair_imp(_T2_param __t2)
+    _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR
+    explicit __libcpp_compressed_pair_imp(_T2_param __t2)
         : __second_(_VSTD::forward<_T2_param>(__t2)) {}
-    _LIBCPP_INLINE_VISIBILITY __libcpp_compressed_pair_imp(_T1_param __t1, _T2_param __t2)
+    _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR
+    __libcpp_compressed_pair_imp(_T1_param __t1, _T2_param __t2)
         : _T1(_VSTD::forward<_T1_param>(__t1)), __second_(_VSTD::forward<_T2_param>(__t2)) {}
 
 #if defined(_LIBCPP_HAS_NO_DEFAULTED_FUNCTIONS) && !defined(_LIBCPP_HAS_NO_RVALUE_REFERENCES)
 
-    _LIBCPP_INLINE_VISIBILITY
+    _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR
     __libcpp_compressed_pair_imp(const __libcpp_compressed_pair_imp& __p)
         _NOEXCEPT_(is_nothrow_copy_constructible<_T1>::value &&
                    is_nothrow_copy_constructible<_T2>::value)
         : _T1(__p.first()), __second_(__p.second()) {}
 
-    _LIBCPP_INLINE_VISIBILITY
+    _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR
     __libcpp_compressed_pair_imp& operator=(const __libcpp_compressed_pair_imp& __p)
         _NOEXCEPT_(is_nothrow_copy_assignable<_T1>::value &&
                    is_nothrow_copy_assignable<_T2>::value)
@@ -2215,13 +2223,13 @@
             return *this;
         }
 
-    _LIBCPP_INLINE_VISIBILITY
+    _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR
     __libcpp_compressed_pair_imp(__libcpp_compressed_pair_imp&& __p)
         _NOEXCEPT_(is_nothrow_move_constructible<_T1>::value &&
                    is_nothrow_move_constructible<_T2>::value)
         : _T1(_VSTD::move(__p.first())), __second_(_VSTD::forward<_T2>(__p.second())) {}
 
-    _LIBCPP_INLINE_VISIBILITY
+    _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR
     __libcpp_compressed_pair_imp& operator=(__libcpp_compressed_pair_imp&& __p)
         _NOEXCEPT_(is_nothrow_move_assignable<_T1>::value &&
                    is_nothrow_move_assignable<_T2>::value)
@@ -2236,7 +2244,7 @@
 #ifndef _LIBCPP_HAS_NO_VARIADICS
 
     template <class... _Args1, class... _Args2, size_t... _I1, size_t... _I2>
-        _LIBCPP_INLINE_VISIBILITY
+        _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR
         __libcpp_compressed_pair_imp(piecewise_construct_t __pc,
                                      tuple<_Args1...> __first_args,
                                      tuple<_Args2...> __second_args,
@@ -2279,25 +2287,29 @@
     typedef const typename remove_reference<_T1>::type& _T1_const_reference;
     typedef const _T2&                                        _T2_const_reference;
 
-    _LIBCPP_INLINE_VISIBILITY __libcpp_compressed_pair_imp() : __first_() {}
-    _LIBCPP_INLINE_VISIBILITY explicit __libcpp_compressed_pair_imp(_T1_param __t1)
+    _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR
+    __libcpp_compressed_pair_imp() : __first_() {}
+    _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR
+    explicit __libcpp_compressed_pair_imp(_T1_param __t1)
         : __first_(_VSTD::forward<_T1_param>(__t1)) {}
-    _LIBCPP_INLINE_VISIBILITY explicit __libcpp_compressed_pair_imp(_T2_param __t2)
+    _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR
+    explicit __libcpp_compressed_pair_imp(_T2_param __t2)
         : _T2(_VSTD::forward<_T2_param>(__t2)), __first_() {}
-    _LIBCPP_INLINE_VISIBILITY __libcpp_compressed_pair_imp(_T1_param __t1, _T2_param __t2)
+    _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR
+    __libcpp_compressed_pair_imp(_T1_param __t1, _T2_param __t2)
         _NOEXCEPT_(is_nothrow_move_constructible<_T1>::value &&
                    is_nothrow_move_constructible<_T2>::value)
         : _T2(_VSTD::forward<_T2_param>(__t2)), __first_(_VSTD::forward<_T1_param>(__t1)) {}
 
 #if defined(_LIBCPP_HAS_NO_DEFAULTED_FUNCTIONS) && !defined(_LIBCPP_HAS_NO_RVALUE_REFERENCES)
 
-    _LIBCPP_INLINE_VISIBILITY
+    _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR
     __libcpp_compressed_pair_imp(const __libcpp_compressed_pair_imp& __p)
         _NOEXCEPT_(is_nothrow_copy_constructible<_T1>::value &&
                    is_nothrow_copy_constructible<_T2>::value)
         : _T2(__p.second()), __first_(__p.first()) {}
 
-    _LIBCPP_INLINE_VISIBILITY
+    _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR
     __libcpp_compressed_pair_imp& operator=(const __libcpp_compressed_pair_imp& __p)
         _NOEXCEPT_(is_nothrow_copy_assignable<_T1>::value &&
                    is_nothrow_copy_assignable<_T2>::value)
@@ -2307,13 +2319,13 @@
             return *this;
         }
 
-    _LIBCPP_INLINE_VISIBILITY
+    _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR
     __libcpp_compressed_pair_imp(__libcpp_compressed_pair_imp&& __p)
         _NOEXCEPT_(is_nothrow_move_constructible<_T1>::value &&
                    is_nothrow_move_constructible<_T2>::value)
         : _T2(_VSTD::forward<_T2>(__p.second())), __first_(_VSTD::move(__p.first())) {}
 
-    _LIBCPP_INLINE_VISIBILITY
+    _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR
     __libcpp_compressed_pair_imp& operator=(__libcpp_compressed_pair_imp&& __p)
         _NOEXCEPT_(is_nothrow_move_assignable<_T1>::value &&
                    is_nothrow_move_assignable<_T2>::value)
@@ -2328,7 +2340,7 @@
 #ifndef _LIBCPP_HAS_NO_VARIADICS
 
     template <class... _Args1, class... _Args2, size_t... _I1, size_t... _I2>
-        _LIBCPP_INLINE_VISIBILITY
+        _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR
         __libcpp_compressed_pair_imp(piecewise_construct_t __pc,
                                      tuple<_Args1...> __first_args,
                                      tuple<_Args2...> __second_args,
@@ -2371,23 +2383,27 @@
     typedef const _T1& _T1_const_reference;
     typedef const _T2& _T2_const_reference;
 
-    _LIBCPP_INLINE_VISIBILITY __libcpp_compressed_pair_imp() {}
-    _LIBCPP_INLINE_VISIBILITY explicit __libcpp_compressed_pair_imp(_T1_param __t1)
+    _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR
+    __libcpp_compressed_pair_imp() {}
+    _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR
+    explicit __libcpp_compressed_pair_imp(_T1_param __t1)
         : _T1(_VSTD::forward<_T1_param>(__t1)) {}
-    _LIBCPP_INLINE_VISIBILITY explicit __libcpp_compressed_pair_imp(_T2_param __t2)
+    _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR
+    explicit __libcpp_compressed_pair_imp(_T2_param __t2)
         : _T2(_VSTD::forward<_T2_param>(__t2)) {}
-    _LIBCPP_INLINE_VISIBILITY __libcpp_compressed_pair_imp(_T1_param __t1, _T2_param __t2)
+    _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR
+    __libcpp_compressed_pair_imp(_T1_param __t1, _T2_param __t2)
         : _T1(_VSTD::forward<_T1_param>(__t1)), _T2(_VSTD::forward<_T2_param>(__t2)) {}
 
 #if defined(_LIBCPP_HAS_NO_DEFAULTED_FUNCTIONS) && !defined(_LIBCPP_HAS_NO_RVALUE_REFERENCES)
 
-    _LIBCPP_INLINE_VISIBILITY
+    _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR
     __libcpp_compressed_pair_imp(const __libcpp_compressed_pair_imp& __p)
         _NOEXCEPT_(is_nothrow_copy_constructible<_T1>::value &&
                    is_nothrow_copy_constructible<_T2>::value)
         : _T1(__p.first()), _T2(__p.second()) {}
 
-    _LIBCPP_INLINE_VISIBILITY
+    _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR
     __libcpp_compressed_pair_imp& operator=(const __libcpp_compressed_pair_imp& __p)
         _NOEXCEPT_(is_nothrow_copy_assignable<_T1>::value &&
                    is_nothrow_copy_assignable<_T2>::value)
@@ -2397,13 +2413,13 @@
             return *this;
         }
 
-    _LIBCPP_INLINE_VISIBILITY
+    _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR
     __libcpp_compressed_pair_imp(__libcpp_compressed_pair_imp&& __p)
         _NOEXCEPT_(is_nothrow_move_constructible<_T1>::value &&
                    is_nothrow_move_constructible<_T2>::value)
         : _T1(_VSTD::move(__p.first())), _T2(_VSTD::move(__p.second())) {}
 
-    _LIBCPP_INLINE_VISIBILITY
+    _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR
     __libcpp_compressed_pair_imp& operator=(__libcpp_compressed_pair_imp&& __p)
         _NOEXCEPT_(is_nothrow_move_assignable<_T1>::value &&
                    is_nothrow_move_assignable<_T2>::value)
@@ -2418,7 +2434,7 @@
 #ifndef _LIBCPP_HAS_NO_VARIADICS
 
     template <class... _Args1, class... _Args2, size_t... _I1, size_t... _I2>
-        _LIBCPP_INLINE_VISIBILITY
+        _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR
         __libcpp_compressed_pair_imp(piecewise_construct_t __pc,
                                      tuple<_Args1...> __first_args,
                                      tuple<_Args2...> __second_args,
@@ -2458,23 +2474,26 @@
     typedef typename base::_T1_const_reference _T1_const_reference;
     typedef typename base::_T2_const_reference _T2_const_reference;
 
-    _LIBCPP_INLINE_VISIBILITY __compressed_pair() {}
-    _LIBCPP_INLINE_VISIBILITY explicit __compressed_pair(_T1_param __t1)
+    _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR __compressed_pair() {}
+    _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR
+    explicit __compressed_pair(_T1_param __t1)
         : base(_VSTD::forward<_T1_param>(__t1)) {}
-    _LIBCPP_INLINE_VISIBILITY explicit __compressed_pair(_T2_param __t2)
+    _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR
+    explicit __compressed_pair(_T2_param __t2)
         : base(_VSTD::forward<_T2_param>(__t2)) {}
-    _LIBCPP_INLINE_VISIBILITY __compressed_pair(_T1_param __t1, _T2_param __t2)
+    _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR
+    __compressed_pair(_T1_param __t1, _T2_param __t2)
         : base(_VSTD::forward<_T1_param>(__t1), _VSTD::forward<_T2_param>(__t2)) {}
 
 #if defined(_LIBCPP_HAS_NO_DEFAULTED_FUNCTIONS) && !defined(_LIBCPP_HAS_NO_RVALUE_REFERENCES)
 
-    _LIBCPP_INLINE_VISIBILITY
+    _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR
     __compressed_pair(const __compressed_pair& __p)
         _NOEXCEPT_(is_nothrow_copy_constructible<_T1>::value &&
                    is_nothrow_copy_constructible<_T2>::value)
         : base(__p) {}
 
-    _LIBCPP_INLINE_VISIBILITY
+    _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR
     __compressed_pair& operator=(const __compressed_pair& __p)
         _NOEXCEPT_(is_nothrow_copy_assignable<_T1>::value &&
                    is_nothrow_copy_assignable<_T2>::value)
@@ -2483,13 +2502,13 @@
             return *this;
         }
 
-    _LIBCPP_INLINE_VISIBILITY
+    _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR
     __compressed_pair(__compressed_pair&& __p)
         _NOEXCEPT_(is_nothrow_move_constructible<_T1>::value &&
                    is_nothrow_move_constructible<_T2>::value)
         : base(_VSTD::move(__p)) {}
 
-    _LIBCPP_INLINE_VISIBILITY
+    _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR
     __compressed_pair& operator=(__compressed_pair&& __p)
         _NOEXCEPT_(is_nothrow_move_assignable<_T1>::value &&
                    is_nothrow_move_assignable<_T2>::value)
@@ -2503,7 +2522,7 @@
 #ifndef _LIBCPP_HAS_NO_VARIADICS
 
     template <class... _Args1, class... _Args2>
-        _LIBCPP_INLINE_VISIBILITY
+        _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR
         __compressed_pair(piecewise_construct_t __pc, tuple<_Args1...> __first_args,
                                                       tuple<_Args2...> __second_args)
             : base(__pc, _VSTD::move(__first_args), _VSTD::move(__second_args),
Index: test/std/utilities/memory/unique.ptr/unique.ptr.runtime/unique.ptr.runtime.ctor/constinit.pass.cpp
===================================================================
--- /dev/null
+++ test/std/utilities/memory/unique.ptr/unique.ptr.runtime/unique.ptr.runtime.ctor/constinit.pass.cpp
@@ -0,0 +1,23 @@
+//===----------------------------------------------------------------------===//
+//
+//                     The LLVM Compiler Infrastructure
+//
+// This file is dual licensed under the MIT and the University of Illinois Open
+// Source Licenses. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+
+// UNSUPPORTED: c++98, c++03, c++11
+
+#include <memory>
+#include <cassert>
+
+#ifndef _LIBCPP_SAFE_STATIC
+#define _LIBCPP_SAFE_STATIC
+#endif
+
+_LIBCPP_SAFE_STATIC static std::unique_ptr<int> a;
+
+int main() {
+    assert(a == nullptr);
+}