diff --git a/libcxx/docs/FeatureTestMacroTable.rst b/libcxx/docs/FeatureTestMacroTable.rst
--- a/libcxx/docs/FeatureTestMacroTable.rst
+++ b/libcxx/docs/FeatureTestMacroTable.rst
@@ -310,6 +310,8 @@
     ------------------------------------------------- -----------------
     ``__cpp_lib_constexpr_cmath``                     *unimplemented*
     ------------------------------------------------- -----------------
+    ``__cpp_lib_constexpr_memory``                    ``202202L``
+    ------------------------------------------------- -----------------
     ``__cpp_lib_constexpr_typeinfo``                  *unimplemented*
     ------------------------------------------------- -----------------
     ``__cpp_lib_invoke_r``                            *unimplemented*
diff --git a/libcxx/docs/ReleaseNotes.rst b/libcxx/docs/ReleaseNotes.rst
--- a/libcxx/docs/ReleaseNotes.rst
+++ b/libcxx/docs/ReleaseNotes.rst
@@ -38,6 +38,7 @@
 Implemented Papers
 ------------------
 - P2499R0 - ``string_view`` range constructor should be ``explicit``
+- P2273R3 - Making ``std::unique_ptr`` constexpr
 
 Improvements and New Features
 -----------------------------
diff --git a/libcxx/docs/Status/Cxx2bPapers.csv b/libcxx/docs/Status/Cxx2bPapers.csv
--- a/libcxx/docs/Status/Cxx2bPapers.csv
+++ b/libcxx/docs/Status/Cxx2bPapers.csv
@@ -44,7 +44,7 @@
 "`P1206R7 <https://wg21.link/P1206R7>`__","LWG","``ranges::to``: A function to convert any range to a container","February 2022","",""
 "`P1413R3 <https://wg21.link/P1413R3>`__","LWG","Deprecate ``std::aligned_storage`` and ``std::aligned_union``","February 2022","",""
 "`P2255R3 <https://wg21.link/P2255R3>`__","LWG","A type trait to detect reference binding to temporary","February 2022","",""
-"`P2273R3 <https://wg21.link/P2273R3>`__","LWG","Making ``std::unique_ptr`` constexpr","February 2022","",""
+"`P2273R3 <https://wg21.link/P2273R3>`__","LWG","Making ``std::unique_ptr`` constexpr","February 2022","|Complete|","16.0"
 "`P2387R3 <https://wg21.link/P2387R3>`__","LWG","Pipe support for user-defined range adaptors","February 2022","",""
 "`P2440R1 <https://wg21.link/P2440R1>`__","LWG","``ranges::iota``, ``ranges::shift_left`` and ``ranges::shift_right``","February 2022","",""
 "`P2441R2 <https://wg21.link/P2441R2>`__","LWG","``views::join_view``","February 2022","",""
diff --git a/libcxx/include/__config b/libcxx/include/__config
--- a/libcxx/include/__config
+++ b/libcxx/include/__config
@@ -849,6 +849,12 @@
 #    define _LIBCPP_CONSTEXPR_AFTER_CXX17
 #  endif
 
+#  if _LIBCPP_STD_VER > 20
+#    define _LIBCPP_CONSTEXPR_CXX23 constexpr
+#  else
+#    define _LIBCPP_CONSTEXPR_CXX23
+#  endif
+
 #  if __has_cpp_attribute(nodiscard) || defined(_LIBCPP_COMPILER_MSVC)
 #    define _LIBCPP_NODISCARD [[nodiscard]]
 #  elif defined(_LIBCPP_COMPILER_CLANG_BASED) && !defined(_LIBCPP_CXX03_LANG)
diff --git a/libcxx/include/__memory/unique_ptr.h b/libcxx/include/__memory/unique_ptr.h
--- a/libcxx/include/__memory/unique_ptr.h
+++ b/libcxx/include/__memory/unique_ptr.h
@@ -37,12 +37,13 @@
   _LIBCPP_INLINE_VISIBILITY default_delete() {}
 #endif
   template <class _Up>
-  _LIBCPP_INLINE_VISIBILITY
+  _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_CXX23
   default_delete(const default_delete<_Up>&,
                  typename enable_if<is_convertible<_Up*, _Tp*>::value>::type* =
                      0) _NOEXCEPT {}
 
-  _LIBCPP_INLINE_VISIBILITY void operator()(_Tp* __ptr) const _NOEXCEPT {
+  _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_CXX23
+  void operator()(_Tp* __ptr) const _NOEXCEPT {
     static_assert(sizeof(_Tp) >= 0, "cannot delete an incomplete type");
     static_assert(!is_void<_Tp>::value, "cannot delete an incomplete type");
     delete __ptr;
@@ -64,12 +65,12 @@
 #endif
 
   template <class _Up>
-  _LIBCPP_INLINE_VISIBILITY
+  _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_CXX23
   default_delete(const default_delete<_Up[]>&,
                  typename _EnableIfConvertible<_Up>::type* = 0) _NOEXCEPT {}
 
   template <class _Up>
-  _LIBCPP_INLINE_VISIBILITY
+  _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_CXX23
   typename _EnableIfConvertible<_Up>::type
   operator()(_Up* __ptr) const _NOEXCEPT {
     static_assert(sizeof(_Up) >= 0, "cannot delete an incomplete type");
@@ -174,18 +175,18 @@
 
   template <bool _Dummy = true,
             class = _EnableIfDeleterDefaultConstructible<_Dummy> >
-  _LIBCPP_INLINE_VISIBILITY
+  _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_CXX23
   explicit unique_ptr(pointer __p) _NOEXCEPT : __ptr_(__p, __value_init_tag()) {}
 
   template <bool _Dummy = true,
             class = _EnableIfDeleterConstructible<_LValRefType<_Dummy> > >
-  _LIBCPP_INLINE_VISIBILITY
+  _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_CXX23
   unique_ptr(pointer __p, _LValRefType<_Dummy> __d) _NOEXCEPT
       : __ptr_(__p, __d) {}
 
   template <bool _Dummy = true,
             class = _EnableIfDeleterConstructible<_GoodRValRefType<_Dummy> > >
-  _LIBCPP_INLINE_VISIBILITY
+  _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_CXX23
   unique_ptr(pointer __p, _GoodRValRefType<_Dummy> __d) _NOEXCEPT
       : __ptr_(__p, _VSTD::move(__d)) {
     static_assert(!is_reference<deleter_type>::value,
@@ -197,7 +198,7 @@
   _LIBCPP_INLINE_VISIBILITY
   unique_ptr(pointer __p, _BadRValRefType<_Dummy> __d) = delete;
 
-  _LIBCPP_INLINE_VISIBILITY
+  _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_CXX23
   unique_ptr(unique_ptr&& __u) _NOEXCEPT
       : __ptr_(__u.release(), _VSTD::forward<deleter_type>(__u.get_deleter())) {
   }
@@ -206,7 +207,7 @@
       class = _EnableIfMoveConvertible<unique_ptr<_Up, _Ep>, _Up>,
       class = _EnableIfDeleterConvertible<_Ep>
   >
-  _LIBCPP_INLINE_VISIBILITY
+  _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_CXX23
   unique_ptr(unique_ptr<_Up, _Ep>&& __u) _NOEXCEPT
       : __ptr_(__u.release(), _VSTD::forward<_Ep>(__u.get_deleter())) {}
 
@@ -220,7 +221,7 @@
       : __ptr_(__p.release(), __value_init_tag()) {}
 #endif
 
-  _LIBCPP_INLINE_VISIBILITY
+  _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_CXX23
   unique_ptr& operator=(unique_ptr&& __u) _NOEXCEPT {
     reset(__u.release());
     __ptr_.second() = _VSTD::forward<deleter_type>(__u.get_deleter());
@@ -231,7 +232,7 @@
       class = _EnableIfMoveConvertible<unique_ptr<_Up, _Ep>, _Up>,
       class = _EnableIfDeleterAssignable<_Ep>
   >
-  _LIBCPP_INLINE_VISIBILITY
+  _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_CXX23
   unique_ptr& operator=(unique_ptr<_Up, _Ep>&& __u) _NOEXCEPT {
     reset(__u.release());
     __ptr_.second() = _VSTD::forward<_Ep>(__u.get_deleter());
@@ -255,49 +256,49 @@
   unique_ptr& operator=(unique_ptr const&) = delete;
 #endif
 
-  _LIBCPP_INLINE_VISIBILITY
+  _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_CXX23
   ~unique_ptr() { reset(); }
 
-  _LIBCPP_INLINE_VISIBILITY
+  _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_CXX23
   unique_ptr& operator=(nullptr_t) _NOEXCEPT {
     reset();
     return *this;
   }
 
-  _LIBCPP_INLINE_VISIBILITY
+  _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_CXX23
   typename add_lvalue_reference<_Tp>::type
   operator*() const {
     return *__ptr_.first();
   }
-  _LIBCPP_INLINE_VISIBILITY
+  _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_CXX23
   pointer operator->() const _NOEXCEPT {
     return __ptr_.first();
   }
-  _LIBCPP_INLINE_VISIBILITY
+  _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_CXX23
   pointer get() const _NOEXCEPT {
     return __ptr_.first();
   }
-  _LIBCPP_INLINE_VISIBILITY
+  _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_CXX23
   deleter_type& get_deleter() _NOEXCEPT {
     return __ptr_.second();
   }
-  _LIBCPP_INLINE_VISIBILITY
+  _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_CXX23
   const deleter_type& get_deleter() const _NOEXCEPT {
     return __ptr_.second();
   }
-  _LIBCPP_INLINE_VISIBILITY
+  _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_CXX23
   explicit operator bool() const _NOEXCEPT {
     return __ptr_.first() != nullptr;
   }
 
-  _LIBCPP_INLINE_VISIBILITY
+  _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_CXX23
   pointer release() _NOEXCEPT {
     pointer __t = __ptr_.first();
     __ptr_.first() = pointer();
     return __t;
   }
 
-  _LIBCPP_INLINE_VISIBILITY
+  _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_CXX23
   void reset(pointer __p = pointer()) _NOEXCEPT {
     pointer __tmp = __ptr_.first();
     __ptr_.first() = __p;
@@ -305,7 +306,7 @@
       __ptr_.second()(__tmp);
   }
 
-  _LIBCPP_INLINE_VISIBILITY
+  _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_CXX23
   void swap(unique_ptr& __u) _NOEXCEPT {
     __ptr_.swap(__u.__ptr_);
   }
@@ -397,27 +398,27 @@
   template <class _Pp, bool _Dummy = true,
             class = _EnableIfDeleterDefaultConstructible<_Dummy>,
             class = _EnableIfPointerConvertible<_Pp> >
-  _LIBCPP_INLINE_VISIBILITY
+  _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_CXX23
   explicit unique_ptr(_Pp __p) _NOEXCEPT
       : __ptr_(__p, __value_init_tag()) {}
 
   template <class _Pp, bool _Dummy = true,
             class = _EnableIfDeleterConstructible<_LValRefType<_Dummy> >,
             class = _EnableIfPointerConvertible<_Pp> >
-  _LIBCPP_INLINE_VISIBILITY
+  _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_CXX23
   unique_ptr(_Pp __p, _LValRefType<_Dummy> __d) _NOEXCEPT
       : __ptr_(__p, __d) {}
 
   template <bool _Dummy = true,
             class = _EnableIfDeleterConstructible<_LValRefType<_Dummy> > >
-  _LIBCPP_INLINE_VISIBILITY
+  _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_CXX23
   unique_ptr(nullptr_t, _LValRefType<_Dummy> __d) _NOEXCEPT
       : __ptr_(nullptr, __d) {}
 
   template <class _Pp, bool _Dummy = true,
             class = _EnableIfDeleterConstructible<_GoodRValRefType<_Dummy> >,
             class = _EnableIfPointerConvertible<_Pp> >
-  _LIBCPP_INLINE_VISIBILITY
+  _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_CXX23
   unique_ptr(_Pp __p, _GoodRValRefType<_Dummy> __d) _NOEXCEPT
       : __ptr_(__p, _VSTD::move(__d)) {
     static_assert(!is_reference<deleter_type>::value,
@@ -426,7 +427,7 @@
 
   template <bool _Dummy = true,
             class = _EnableIfDeleterConstructible<_GoodRValRefType<_Dummy> > >
-  _LIBCPP_INLINE_VISIBILITY
+  _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_CXX23
   unique_ptr(nullptr_t, _GoodRValRefType<_Dummy> __d) _NOEXCEPT
       : __ptr_(nullptr, _VSTD::move(__d)) {
     static_assert(!is_reference<deleter_type>::value,
@@ -439,12 +440,12 @@
   _LIBCPP_INLINE_VISIBILITY
   unique_ptr(_Pp __p, _BadRValRefType<_Dummy> __d) = delete;
 
-  _LIBCPP_INLINE_VISIBILITY
+  _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_CXX23
   unique_ptr(unique_ptr&& __u) _NOEXCEPT
       : __ptr_(__u.release(), _VSTD::forward<deleter_type>(__u.get_deleter())) {
   }
 
-  _LIBCPP_INLINE_VISIBILITY
+  _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_CXX23
   unique_ptr& operator=(unique_ptr&& __u) _NOEXCEPT {
     reset(__u.release());
     __ptr_.second() = _VSTD::forward<deleter_type>(__u.get_deleter());
@@ -455,7 +456,7 @@
       class = _EnableIfMoveConvertible<unique_ptr<_Up, _Ep>, _Up>,
       class = _EnableIfDeleterConvertible<_Ep>
   >
-  _LIBCPP_INLINE_VISIBILITY
+  _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_CXX23
   unique_ptr(unique_ptr<_Up, _Ep>&& __u) _NOEXCEPT
       : __ptr_(__u.release(), _VSTD::forward<_Ep>(__u.get_deleter())) {
   }
@@ -464,7 +465,7 @@
       class = _EnableIfMoveConvertible<unique_ptr<_Up, _Ep>, _Up>,
       class = _EnableIfDeleterAssignable<_Ep>
   >
-  _LIBCPP_INLINE_VISIBILITY
+  _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_CXX23
   unique_ptr&
   operator=(unique_ptr<_Up, _Ep>&& __u) _NOEXCEPT {
     reset(__u.release());
@@ -477,40 +478,40 @@
   unique_ptr& operator=(unique_ptr const&) = delete;
 #endif
 public:
-  _LIBCPP_INLINE_VISIBILITY
+  _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_CXX23
   ~unique_ptr() { reset(); }
 
-  _LIBCPP_INLINE_VISIBILITY
+  _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_CXX23
   unique_ptr& operator=(nullptr_t) _NOEXCEPT {
     reset();
     return *this;
   }
 
-  _LIBCPP_INLINE_VISIBILITY
+  _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_CXX23
   typename add_lvalue_reference<_Tp>::type
   operator[](size_t __i) const {
     return __ptr_.first()[__i];
   }
-  _LIBCPP_INLINE_VISIBILITY
+  _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_CXX23
   pointer get() const _NOEXCEPT {
     return __ptr_.first();
   }
 
-  _LIBCPP_INLINE_VISIBILITY
+  _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_CXX23
   deleter_type& get_deleter() _NOEXCEPT {
     return __ptr_.second();
   }
 
-  _LIBCPP_INLINE_VISIBILITY
+  _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_CXX23
   const deleter_type& get_deleter() const _NOEXCEPT {
     return __ptr_.second();
   }
-  _LIBCPP_INLINE_VISIBILITY
+  _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_CXX23
   explicit operator bool() const _NOEXCEPT {
     return __ptr_.first() != nullptr;
   }
 
-  _LIBCPP_INLINE_VISIBILITY
+  _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_CXX23
   pointer release() _NOEXCEPT {
     pointer __t = __ptr_.first();
     __ptr_.first() = pointer();
@@ -518,7 +519,7 @@
   }
 
   template <class _Pp>
-  _LIBCPP_INLINE_VISIBILITY
+  _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_CXX23
   typename enable_if<
       _CheckArrayPointerConversion<_Pp>::value
   >::type
@@ -529,7 +530,7 @@
       __ptr_.second()(__tmp);
   }
 
-  _LIBCPP_INLINE_VISIBILITY
+  _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_CXX23
   void reset(nullptr_t = nullptr) _NOEXCEPT {
     pointer __tmp = __ptr_.first();
     __ptr_.first() = nullptr;
@@ -537,7 +538,7 @@
       __ptr_.second()(__tmp);
   }
 
-  _LIBCPP_INLINE_VISIBILITY
+  _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_CXX23
   void swap(unique_ptr& __u) _NOEXCEPT {
     __ptr_.swap(__u.__ptr_);
   }
@@ -545,7 +546,7 @@
 };
 
 template <class _Tp, class _Dp>
-inline _LIBCPP_INLINE_VISIBILITY
+inline _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_CXX23
 typename enable_if<
     __is_swappable<_Dp>::value,
     void
@@ -553,17 +554,17 @@
 swap(unique_ptr<_Tp, _Dp>& __x, unique_ptr<_Tp, _Dp>& __y) _NOEXCEPT {__x.swap(__y);}
 
 template <class _T1, class _D1, class _T2, class _D2>
-inline _LIBCPP_INLINE_VISIBILITY
+inline _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_CXX23
 bool
 operator==(const unique_ptr<_T1, _D1>& __x, const unique_ptr<_T2, _D2>& __y) {return __x.get() == __y.get();}
 
 template <class _T1, class _D1, class _T2, class _D2>
-inline _LIBCPP_INLINE_VISIBILITY
+inline _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_CXX23
 bool
 operator!=(const unique_ptr<_T1, _D1>& __x, const unique_ptr<_T2, _D2>& __y) {return !(__x == __y);}
 
 template <class _T1, class _D1, class _T2, class _D2>
-inline _LIBCPP_INLINE_VISIBILITY
+inline _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_CXX23
 bool
 operator< (const unique_ptr<_T1, _D1>& __x, const unique_ptr<_T2, _D2>& __y)
 {
@@ -574,22 +575,22 @@
 }
 
 template <class _T1, class _D1, class _T2, class _D2>
-inline _LIBCPP_INLINE_VISIBILITY
+inline _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_CXX23
 bool
 operator> (const unique_ptr<_T1, _D1>& __x, const unique_ptr<_T2, _D2>& __y) {return __y < __x;}
 
 template <class _T1, class _D1, class _T2, class _D2>
-inline _LIBCPP_INLINE_VISIBILITY
+inline _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_CXX23
 bool
 operator<=(const unique_ptr<_T1, _D1>& __x, const unique_ptr<_T2, _D2>& __y) {return !(__y < __x);}
 
 template <class _T1, class _D1, class _T2, class _D2>
-inline _LIBCPP_INLINE_VISIBILITY
+inline _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_CXX23
 bool
 operator>=(const unique_ptr<_T1, _D1>& __x, const unique_ptr<_T2, _D2>& __y) {return !(__x < __y);}
 
 template <class _T1, class _D1>
-inline _LIBCPP_INLINE_VISIBILITY
+inline _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_CXX23
 bool
 operator==(const unique_ptr<_T1, _D1>& __x, nullptr_t) _NOEXCEPT
 {
@@ -597,7 +598,7 @@
 }
 
 template <class _T1, class _D1>
-inline _LIBCPP_INLINE_VISIBILITY
+inline _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_CXX23
 bool
 operator==(nullptr_t, const unique_ptr<_T1, _D1>& __x) _NOEXCEPT
 {
@@ -605,7 +606,7 @@
 }
 
 template <class _T1, class _D1>
-inline _LIBCPP_INLINE_VISIBILITY
+inline _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_CXX23
 bool
 operator!=(const unique_ptr<_T1, _D1>& __x, nullptr_t) _NOEXCEPT
 {
@@ -613,7 +614,7 @@
 }
 
 template <class _T1, class _D1>
-inline _LIBCPP_INLINE_VISIBILITY
+inline _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_CXX23
 bool
 operator!=(nullptr_t, const unique_ptr<_T1, _D1>& __x) _NOEXCEPT
 {
@@ -621,7 +622,7 @@
 }
 
 template <class _T1, class _D1>
-inline _LIBCPP_INLINE_VISIBILITY
+inline _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_CXX23
 bool
 operator<(const unique_ptr<_T1, _D1>& __x, nullptr_t)
 {
@@ -630,7 +631,7 @@
 }
 
 template <class _T1, class _D1>
-inline _LIBCPP_INLINE_VISIBILITY
+inline _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_CXX23
 bool
 operator<(nullptr_t, const unique_ptr<_T1, _D1>& __x)
 {
@@ -639,7 +640,7 @@
 }
 
 template <class _T1, class _D1>
-inline _LIBCPP_INLINE_VISIBILITY
+inline _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_CXX23
 bool
 operator>(const unique_ptr<_T1, _D1>& __x, nullptr_t)
 {
@@ -647,7 +648,7 @@
 }
 
 template <class _T1, class _D1>
-inline _LIBCPP_INLINE_VISIBILITY
+inline _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_CXX23
 bool
 operator>(nullptr_t, const unique_ptr<_T1, _D1>& __x)
 {
@@ -655,7 +656,7 @@
 }
 
 template <class _T1, class _D1>
-inline _LIBCPP_INLINE_VISIBILITY
+inline _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_CXX23
 bool
 operator<=(const unique_ptr<_T1, _D1>& __x, nullptr_t)
 {
@@ -663,7 +664,7 @@
 }
 
 template <class _T1, class _D1>
-inline _LIBCPP_INLINE_VISIBILITY
+inline _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_CXX23
 bool
 operator<=(nullptr_t, const unique_ptr<_T1, _D1>& __x)
 {
@@ -671,7 +672,7 @@
 }
 
 template <class _T1, class _D1>
-inline _LIBCPP_INLINE_VISIBILITY
+inline _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_CXX23
 bool
 operator>=(const unique_ptr<_T1, _D1>& __x, nullptr_t)
 {
@@ -679,7 +680,7 @@
 }
 
 template <class _T1, class _D1>
-inline _LIBCPP_INLINE_VISIBILITY
+inline _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_CXX23
 bool
 operator>=(nullptr_t, const unique_ptr<_T1, _D1>& __x)
 {
@@ -707,7 +708,7 @@
 };
 
 template<class _Tp, class... _Args>
-inline _LIBCPP_INLINE_VISIBILITY
+inline _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_CXX23
 typename __unique_if<_Tp>::__unique_single
 make_unique(_Args&&... __args)
 {
@@ -715,7 +716,7 @@
 }
 
 template<class _Tp>
-inline _LIBCPP_INLINE_VISIBILITY
+inline _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_CXX23
 typename __unique_if<_Tp>::__unique_array_unknown_bound
 make_unique(size_t __n)
 {
diff --git a/libcxx/include/version b/libcxx/include/version
--- a/libcxx/include/version
+++ b/libcxx/include/version
@@ -61,7 +61,8 @@
 __cpp_lib_constexpr_dynamic_alloc                       201907L <memory>
 __cpp_lib_constexpr_functional                          201907L <functional>
 __cpp_lib_constexpr_iterator                            201811L <iterator>
-__cpp_lib_constexpr_memory                              201811L <memory>
+__cpp_lib_constexpr_memory                              202202L <memory>
+                                                        201811L // C++20
 __cpp_lib_constexpr_numeric                             201911L <numeric>
 __cpp_lib_constexpr_string                              201907L <string>
 __cpp_lib_constexpr_string_view                         201811L <string_view>
@@ -381,6 +382,8 @@
 // # define __cpp_lib_bind_back                            202202L
 # define __cpp_lib_byteswap                             202110L
 // # define __cpp_lib_constexpr_cmath                      202202L
+# undef  __cpp_lib_constexpr_memory
+# define __cpp_lib_constexpr_memory                     202202L
 // # define __cpp_lib_constexpr_typeinfo                   202106L
 // # define __cpp_lib_invoke_r                             202106L
 # define __cpp_lib_is_scoped_enum                       202011L
diff --git a/libcxx/test/std/language.support/support.limits/support.limits.general/memory.version.compile.pass.cpp b/libcxx/test/std/language.support/support.limits/support.limits.general/memory.version.compile.pass.cpp
--- a/libcxx/test/std/language.support/support.limits/support.limits.general/memory.version.compile.pass.cpp
+++ b/libcxx/test/std/language.support/support.limits/support.limits.general/memory.version.compile.pass.cpp
@@ -23,6 +23,7 @@
     __cpp_lib_atomic_value_initialization         201911L [C++20]
     __cpp_lib_constexpr_dynamic_alloc             201907L [C++20]
     __cpp_lib_constexpr_memory                    201811L [C++20]
+                                                  202202L [C++2b]
     __cpp_lib_enable_shared_from_this             201603L [C++17]
     __cpp_lib_make_unique                         201304L [C++14]
     __cpp_lib_out_ptr                             202106L [C++2b]
@@ -454,8 +455,8 @@
 # ifndef __cpp_lib_constexpr_memory
 #   error "__cpp_lib_constexpr_memory should be defined in c++2b"
 # endif
-# if __cpp_lib_constexpr_memory != 201811L
-#   error "__cpp_lib_constexpr_memory should have the value 201811L in c++2b"
+# if __cpp_lib_constexpr_memory != 202202L
+#   error "__cpp_lib_constexpr_memory should have the value 202202L in c++2b"
 # endif
 
 # ifndef __cpp_lib_enable_shared_from_this
diff --git a/libcxx/test/std/language.support/support.limits/support.limits.general/version.version.compile.pass.cpp b/libcxx/test/std/language.support/support.limits/support.limits.general/version.version.compile.pass.cpp
--- a/libcxx/test/std/language.support/support.limits/support.limits.general/version.version.compile.pass.cpp
+++ b/libcxx/test/std/language.support/support.limits/support.limits.general/version.version.compile.pass.cpp
@@ -58,6 +58,7 @@
     __cpp_lib_constexpr_functional                 201907L [C++20]
     __cpp_lib_constexpr_iterator                   201811L [C++20]
     __cpp_lib_constexpr_memory                     201811L [C++20]
+                                                   202202L [C++2b]
     __cpp_lib_constexpr_numeric                    201911L [C++20]
     __cpp_lib_constexpr_string                     201907L [C++20]
     __cpp_lib_constexpr_string_view                201811L [C++20]
@@ -3915,8 +3916,8 @@
 # ifndef __cpp_lib_constexpr_memory
 #   error "__cpp_lib_constexpr_memory should be defined in c++2b"
 # endif
-# if __cpp_lib_constexpr_memory != 201811L
-#   error "__cpp_lib_constexpr_memory should have the value 201811L in c++2b"
+# if __cpp_lib_constexpr_memory != 202202L
+#   error "__cpp_lib_constexpr_memory should have the value 202202L in c++2b"
 # endif
 
 # ifndef __cpp_lib_constexpr_numeric
diff --git a/libcxx/test/std/utilities/smartptr/unique.ptr/unique.ptr.special/cmp_nullptr.pass.cpp b/libcxx/test/std/utilities/smartptr/unique.ptr/unique.ptr.special/cmp_nullptr.pass.cpp
--- a/libcxx/test/std/utilities/smartptr/unique.ptr/unique.ptr.special/cmp_nullptr.pass.cpp
+++ b/libcxx/test/std/utilities/smartptr/unique.ptr/unique.ptr.special/cmp_nullptr.pass.cpp
@@ -8,7 +8,7 @@
 
 // <memory>
 
-// shared_ptr
+// unique_ptr
 
 // template <class T, class D>
 //     bool operator==(const unique_ptr<T, D>& x, nullptr_t) noexcept;
@@ -37,36 +37,48 @@
 
 #include <memory>
 #include <cassert>
+#include <type_traits>
 
 #include "test_macros.h"
 
-void do_nothing(int*) {}
-
-int main(int, char**)
-{
-    const std::unique_ptr<int> p1(new int(1));
-    assert(!(p1 == nullptr));
-    assert(!(nullptr == p1));
+TEST_CONSTEXPR_CXX23 bool test() {
+  const std::unique_ptr<int> p1(new int(1));
+  assert(!(p1 == nullptr));
+  assert(!(nullptr == p1));
+#if TEST_STD_VER >= 23
+  // checks below have unspecified value so can't be used in compile time.
+  if (!std::is_constant_evaluated())
+#endif
+  {
     assert(!(p1 < nullptr));
-    assert( (nullptr < p1));
+    assert((nullptr < p1));
     assert(!(p1 <= nullptr));
-    assert( (nullptr <= p1));
-    assert( (p1 > nullptr));
+    assert((nullptr <= p1));
+    assert((p1 > nullptr));
     assert(!(nullptr > p1));
-    assert( (p1 >= nullptr));
+    assert((p1 >= nullptr));
     assert(!(nullptr >= p1));
+  }
+  const std::unique_ptr<int> p2;
+  assert((p2 == nullptr));
+  assert((nullptr == p2));
+  assert(!(p2 < nullptr));
+  assert(!(nullptr < p2));
+  assert((p2 <= nullptr));
+  assert((nullptr <= p2));
+  assert(!(p2 > nullptr));
+  assert(!(nullptr > p2));
+  assert((p2 >= nullptr));
+  assert((nullptr >= p2));
+
+  return true;
+}
 
-    const std::unique_ptr<int> p2;
-    assert( (p2 == nullptr));
-    assert( (nullptr == p2));
-    assert(!(p2 < nullptr));
-    assert(!(nullptr < p2));
-    assert( (p2 <= nullptr));
-    assert( (nullptr <= p2));
-    assert(!(p2 > nullptr));
-    assert(!(nullptr > p2));
-    assert( (p2 >= nullptr));
-    assert( (nullptr >= p2));
+int main(int, char**) {
+  assert(test());
+#if TEST_STD_VER >= 23
+  static_assert(test());
+#endif // TEST_STD_VER
 
   return 0;
 }
diff --git a/libcxx/test/support/test_macros.h b/libcxx/test/support/test_macros.h
--- a/libcxx/test/support/test_macros.h
+++ b/libcxx/test/support/test_macros.h
@@ -166,6 +166,12 @@
 # define TEST_CONSTEXPR_CXX20
 #endif
 
+#if TEST_STD_VER >= 23
+# define TEST_CONSTEXPR_CXX23 constexpr
+#else
+# define TEST_CONSTEXPR_CXX23
+#endif
+
 #define TEST_ALIGNAS_TYPE(...) TEST_ALIGNAS(TEST_ALIGNOF(__VA_ARGS__))
 
 #if !TEST_HAS_FEATURE(cxx_rtti) && !defined(__cpp_rtti) \
diff --git a/libcxx/utils/generate_feature_test_macro_components.py b/libcxx/utils/generate_feature_test_macro_components.py
--- a/libcxx/utils/generate_feature_test_macro_components.py
+++ b/libcxx/utils/generate_feature_test_macro_components.py
@@ -238,7 +238,7 @@
     "headers": ["iterator"],
   }, {
     "name": "__cpp_lib_constexpr_memory",
-    "values": { "c++20": 201811 },
+    "values": { "c++20": 201811, "c++2b": 202202 },
     "headers": ["memory"],
   }, {
     "name": "__cpp_lib_constexpr_numeric",