diff --git a/libcxx/include/__config b/libcxx/include/__config
index b4c081dcdff1b..357f77b7d27d6 100644
--- a/libcxx/include/__config
+++ b/libcxx/include/__config
@@ -1050,8 +1050,7 @@ typedef __char32_t char32_t;
 #    define _LIBCPP_CTAD_SUPPORTED_FOR_TYPE(_ClassName) static_assert(true, "")
 #  endif
 
-// TODO(LLVM 22): Remove the workaround
-#  if defined(__OBJC__) && (!defined(_LIBCPP_CLANG_VER) || _LIBCPP_CLANG_VER < 2001)
+#  if defined(__OBJC__) && defined(_LIBCPP_APPLE_CLANG_VER)
 #    define _LIBCPP_WORKAROUND_OBJCXX_COMPILER_INTRINSICS
 #  endif
 
@@ -1255,14 +1254,6 @@ typedef __char32_t char32_t;
 #    define _LIBCPP_DIAGNOSE_NULLPTR
 #  endif
 
-// TODO(LLVM 22): Remove this macro once LLVM19 support ends. __cpp_explicit_this_parameter has been set in LLVM20.
-// Clang-18 has support for deducing this, but it does not set the FTM.
-#  if defined(__cpp_explicit_this_parameter) || (defined(_LIBCPP_CLANG_VER) && _LIBCPP_CLANG_VER >= 1800)
-#    define _LIBCPP_HAS_EXPLICIT_THIS_PARAMETER 1
-#  else
-#    define _LIBCPP_HAS_EXPLICIT_THIS_PARAMETER 0
-#  endif
-
 #endif // __cplusplus
 
 #endif // _LIBCPP___CONFIG
diff --git a/libcxx/include/__configuration/abi.h b/libcxx/include/__configuration/abi.h
index c9936df30ff7f..38b85c6ac70de 100644
--- a/libcxx/include/__configuration/abi.h
+++ b/libcxx/include/__configuration/abi.h
@@ -61,14 +61,6 @@
 // According to the Standard, `bitset::operator[] const` returns bool
 #  define _LIBCPP_ABI_BITSET_VECTOR_BOOL_CONST_SUBSCRIPT_RETURN_BOOL
 
-// In LLVM 20, we've changed to take these ABI breaks unconditionally. These flags only exist in case someone is running
-// into the static_asserts we added to catch the ABI break and don't care that it is one.
-// TODO(LLVM 22): Remove these flags
-#  define _LIBCPP_ABI_LIST_REMOVE_NODE_POINTER_UB
-#  define _LIBCPP_ABI_TREE_REMOVE_NODE_POINTER_UB
-#  define _LIBCPP_ABI_FIX_UNORDERED_NODE_POINTER_UB
-#  define _LIBCPP_ABI_FORWARD_LIST_REMOVE_NODE_POINTER_UB
-
 // These flags are documented in ABIGuarantees.rst
 #  define _LIBCPP_ABI_ALTERNATE_STRING_LAYOUT
 #  define _LIBCPP_ABI_DO_NOT_EXPORT_BASIC_STRING_COMMON
diff --git a/libcxx/include/__format/format_arg.h b/libcxx/include/__format/format_arg.h
index ed5e76275ea87..19794f0f084ce 100644
--- a/libcxx/include/__format/format_arg.h
+++ b/libcxx/include/__format/format_arg.h
@@ -149,7 +149,7 @@ _LIBCPP_HIDE_FROM_ABI decltype(auto) __visit_format_arg(_Visitor&& __vis, basic_
   __libcpp_unreachable();
 }
 
-#  if _LIBCPP_STD_VER >= 26 && _LIBCPP_HAS_EXPLICIT_THIS_PARAMETER
+#  if _LIBCPP_STD_VER >= 26
 
 template <class _Rp, class _Visitor, class _Context>
 _LIBCPP_HIDE_FROM_ABI _Rp __visit_format_arg(_Visitor&& __vis, basic_format_arg<_Context> __arg) {
@@ -200,7 +200,7 @@ _LIBCPP_HIDE_FROM_ABI _Rp __visit_format_arg(_Visitor&& __vis, basic_format_arg<
   __libcpp_unreachable();
 }
 
-#  endif // _LIBCPP_STD_VER >= 26 && _LIBCPP_HAS_EXPLICIT_THIS_PARAMETER
+#  endif // _LIBCPP_STD_VER >= 26
 
 /// Contains the values used in basic_format_arg.
 ///
@@ -285,7 +285,7 @@ class _LIBCPP_NO_SPECIALIZATIONS basic_format_arg {
 
   _LIBCPP_HIDE_FROM_ABI explicit operator bool() const noexcept { return __type_ != __format::__arg_t::__none; }
 
-#  if _LIBCPP_STD_VER >= 26 && _LIBCPP_HAS_EXPLICIT_THIS_PARAMETER
+#  if _LIBCPP_STD_VER >= 26
 
   // This function is user facing, so it must wrap the non-standard types of
   // the "variant" in a handle to stay conforming. See __arg_t for more details.
@@ -329,7 +329,7 @@ class _LIBCPP_NO_SPECIALIZATIONS basic_format_arg {
     }
   }
 
-#  endif // _LIBCPP_STD_VER >= 26 && _LIBCPP_HAS_EXPLICIT_THIS_PARAMETER
+#  endif // _LIBCPP_STD_VER >= 26
 
 private:
   using char_type = typename _Context::char_type;
@@ -371,11 +371,8 @@ class basic_format_arg<_Context>::handle {
 // This function is user facing, so it must wrap the non-standard types of
 // the "variant" in a handle to stay conforming. See __arg_t for more details.
 template <class _Visitor, class _Context>
-#  if _LIBCPP_STD_VER >= 26 && _LIBCPP_HAS_EXPLICIT_THIS_PARAMETER
-_LIBCPP_DEPRECATED_IN_CXX26
-#  endif
-    _LIBCPP_HIDE_FROM_ABI decltype(auto)
-    visit_format_arg(_Visitor&& __vis, basic_format_arg<_Context> __arg) {
+_LIBCPP_DEPRECATED_IN_CXX26 _LIBCPP_HIDE_FROM_ABI decltype(auto)
+visit_format_arg(_Visitor&& __vis, basic_format_arg<_Context> __arg) {
   switch (__arg.__type_) {
 #  if _LIBCPP_HAS_INT128
   case __format::__arg_t::__i128: {
@@ -387,7 +384,7 @@ _LIBCPP_DEPRECATED_IN_CXX26
     typename __basic_format_arg_value<_Context>::__handle __h{__arg.__value_.__u128_};
     return std::invoke(std::forward<_Visitor>(__vis), typename basic_format_arg<_Context>::handle{__h});
   }
-#  endif // _LIBCPP_STD_VER >= 26 && _LIBCPP_HAS_EXPLICIT_THIS_PARAMETER
+#  endif // _LIBCPP_HAS_INT128
   default:
     return std::__visit_format_arg(std::forward<_Visitor>(__vis), __arg);
   }
diff --git a/libcxx/include/__format/format_context.h b/libcxx/include/__format/format_context.h
index e672ee7ad0581..1771dd34b82fb 100644
--- a/libcxx/include/__format/format_context.h
+++ b/libcxx/include/__format/format_context.h
@@ -175,13 +175,13 @@ class basic_format_context<typename __format::__retarget_buffer<_CharT>::__itera
                   __format::__determine_arg_t<basic_format_context, decltype(__arg)>(),
                   __basic_format_arg_value<basic_format_context>(__arg)};
           };
-#  if _LIBCPP_STD_VER >= 26 && _LIBCPP_HAS_EXPLICIT_THIS_PARAMETER
+#  if _LIBCPP_STD_VER >= 26
           return static_cast<_Context*>(__c)->arg(__id).visit(std::move(__visitor));
 #  else
           _LIBCPP_SUPPRESS_DEPRECATED_PUSH
           return std::visit_format_arg(std::move(__visitor), static_cast<_Context*>(__c)->arg(__id));
           _LIBCPP_SUPPRESS_DEPRECATED_POP
-#  endif // _LIBCPP_STD_VER >= 26 && _LIBCPP_HAS_EXPLICIT_THIS_PARAMETER
+#  endif // _LIBCPP_STD_VER >= 26
         }) {
   }
 
diff --git a/libcxx/include/__hash_table b/libcxx/include/__hash_table
index 5432abb4ab39d..e1897949a47e6 100644
--- a/libcxx/include/__hash_table
+++ b/libcxx/include/__hash_table
@@ -83,18 +83,6 @@ struct __hash_node_base {
   typedef _NodePtr __node_pointer;
   typedef __node_base_pointer __next_pointer;
 
-// TODO(LLVM 22): Remove this check
-#ifndef _LIBCPP_ABI_FIX_UNORDERED_NODE_POINTER_UB
-  static_assert(sizeof(__node_base_pointer) == sizeof(__node_pointer) && _LIBCPP_ALIGNOF(__node_base_pointer) ==
-                    _LIBCPP_ALIGNOF(__node_pointer),
-                "It looks like you are using std::__hash_table (an implementation detail for the unordered containers) "
-                "with a fancy pointer type that thas a different representation depending on whether it points to a "
-                "__hash_table base pointer or a __hash_table node pointer (both of which are implementation details of "
-                "the standard library). This means that your ABI is being broken between LLVM 19 and LLVM 20. If you "
-                "don't care about your ABI being broken, define the _LIBCPP_ABI_TREE_REMOVE_NODE_POINTER_UB macro to "
-                "silence this diagnostic.");
-#endif
-
   __next_pointer __next_;
 
   _LIBCPP_HIDE_FROM_ABI __next_pointer __ptr() _NOEXCEPT {
diff --git a/libcxx/include/__iterator/concepts.h b/libcxx/include/__iterator/concepts.h
index f38688734b38a..3b43920443636 100644
--- a/libcxx/include/__iterator/concepts.h
+++ b/libcxx/include/__iterator/concepts.h
@@ -117,15 +117,12 @@ template <class _Tp>
 concept __signed_integer_like = signed_integral<_Tp>;
 
 template <class _Ip>
-concept weakly_incrementable =
-    // TODO: remove this once the clang bug is fixed (https://llvm.org/PR48173).
-    !same_as<_Ip, bool> && // Currently, clang does not handle bool correctly.
-    movable<_Ip> && requires(_Ip __i) {
-      typename iter_difference_t<_Ip>;
-      requires __signed_integer_like<iter_difference_t<_Ip>>;
-      { ++__i } -> same_as<_Ip&>; // not required to be equality-preserving
-      __i++;                      // not required to be equality-preserving
-    };
+concept weakly_incrementable = movable<_Ip> && requires(_Ip __i) {
+  typename iter_difference_t<_Ip>;
+  requires __signed_integer_like<iter_difference_t<_Ip>>;
+  { ++__i } -> same_as<_Ip&>; // not required to be equality-preserving
+  __i++;                      // not required to be equality-preserving
+};
 
 // [iterator.concept.inc]
 template <class _Ip>
diff --git a/libcxx/include/__math/traits.h b/libcxx/include/__math/traits.h
index 00db2a8289fb3..ff22cee7305d7 100644
--- a/libcxx/include/__math/traits.h
+++ b/libcxx/include/__math/traits.h
@@ -25,33 +25,26 @@ namespace __math {
 
 // signbit
 
-// TODO(LLVM 22): Remove conditional once support for Clang 19 is dropped.
-#if defined(_LIBCPP_COMPILER_GCC) || __has_constexpr_builtin(__builtin_signbit)
-#  define _LIBCPP_SIGNBIT_CONSTEXPR _LIBCPP_CONSTEXPR_SINCE_CXX23
-#else
-#  define _LIBCPP_SIGNBIT_CONSTEXPR
-#endif
-
 // The universal C runtime (UCRT) in the WinSDK provides floating point overloads
 // for std::signbit(). By defining our overloads as templates, we can work around
 // this issue as templates are less preferred than non-template functions.
 template <class = void>
-[[__nodiscard__]] inline _LIBCPP_SIGNBIT_CONSTEXPR _LIBCPP_HIDE_FROM_ABI bool signbit(float __x) _NOEXCEPT {
+[[__nodiscard__]] inline _LIBCPP_CONSTEXPR_SINCE_CXX23 _LIBCPP_HIDE_FROM_ABI bool signbit(float __x) _NOEXCEPT {
   return __builtin_signbit(__x);
 }
 
 template <class = void>
-[[__nodiscard__]] inline _LIBCPP_SIGNBIT_CONSTEXPR _LIBCPP_HIDE_FROM_ABI bool signbit(double __x) _NOEXCEPT {
+[[__nodiscard__]] inline _LIBCPP_CONSTEXPR_SINCE_CXX23 _LIBCPP_HIDE_FROM_ABI bool signbit(double __x) _NOEXCEPT {
   return __builtin_signbit(__x);
 }
 
 template <class = void>
-[[__nodiscard__]] inline _LIBCPP_SIGNBIT_CONSTEXPR _LIBCPP_HIDE_FROM_ABI bool signbit(long double __x) _NOEXCEPT {
+[[__nodiscard__]] inline _LIBCPP_CONSTEXPR_SINCE_CXX23 _LIBCPP_HIDE_FROM_ABI bool signbit(long double __x) _NOEXCEPT {
   return __builtin_signbit(__x);
 }
 
 template <class _A1, __enable_if_t<is_integral<_A1>::value, int> = 0>
-[[__nodiscard__]] inline _LIBCPP_SIGNBIT_CONSTEXPR _LIBCPP_HIDE_FROM_ABI bool signbit(_A1 __x) _NOEXCEPT {
+[[__nodiscard__]] inline _LIBCPP_CONSTEXPR_SINCE_CXX23 _LIBCPP_HIDE_FROM_ABI bool signbit(_A1 __x) _NOEXCEPT {
   return __x < 0;
 }
 
diff --git a/libcxx/include/__ranges/transform_view.h b/libcxx/include/__ranges/transform_view.h
index ae85dfa452d72..ab1adf9cdbe68 100644
--- a/libcxx/include/__ranges/transform_view.h
+++ b/libcxx/include/__ranges/transform_view.h
@@ -13,7 +13,6 @@
 #include <__compare/three_way_comparable.h>
 #include <__concepts/constructible.h>
 #include <__concepts/convertible_to.h>
-#include <__concepts/copyable.h>
 #include <__concepts/derived_from.h>
 #include <__concepts/equality_comparable.h>
 #include <__concepts/invocable.h>
@@ -64,7 +63,7 @@ concept __regular_invocable_with_range_ref = regular_invocable<_Fn, range_refere
 template <class _View, class _Fn>
 concept __transform_view_constraints =
     view<_View> && is_object_v<_Fn> && regular_invocable<_Fn&, range_reference_t<_View>> &&
-    __is_referenceable_v<invoke_result_t<_Fn&, range_reference_t<_View>>>;
+    __referenceable<invoke_result_t<_Fn&, range_reference_t<_View>>>;
 
 #  if _LIBCPP_STD_VER >= 23
 template <input_range _View, move_constructible _Fn>
diff --git a/libcxx/include/__tree b/libcxx/include/__tree
index 0738c8c6a5e2b..694796922c914 100644
--- a/libcxx/include/__tree
+++ b/libcxx/include/__tree
@@ -823,18 +823,6 @@ public:
   using __node_allocator _LIBCPP_NODEBUG = __rebind_alloc<__alloc_traits, __node>;
   using __node_traits _LIBCPP_NODEBUG    = allocator_traits<__node_allocator>;
 
-// TODO(LLVM 22): Remove this check
-#ifndef _LIBCPP_ABI_TREE_REMOVE_NODE_POINTER_UB
-  static_assert(sizeof(__node_base_pointer) == sizeof(__end_node_pointer) && _LIBCPP_ALIGNOF(__node_base_pointer) ==
-                    _LIBCPP_ALIGNOF(__end_node_pointer),
-                "It looks like you are using std::__tree (an implementation detail for (multi)map/set) with a fancy "
-                "pointer type that thas a different representation depending on whether it points to a __tree base "
-                "pointer or a __tree node pointer (both of which are implementation details of the standard library). "
-                "This means that your ABI is being broken between LLVM 19 and LLVM 20. If you don't care about your "
-                "ABI being broken, define the _LIBCPP_ABI_TREE_REMOVE_NODE_POINTER_UB macro to silence this "
-                "diagnostic.");
-#endif
-
 private:
   // check for sane allocator pointer rebinding semantics. Rebinding the
   // allocator for a new pointer type should be exactly the same as rebinding
diff --git a/libcxx/include/__type_traits/reference_constructs_from_temporary.h b/libcxx/include/__type_traits/reference_constructs_from_temporary.h
index 2ff549b4e15ce..3d097ce90cb09 100644
--- a/libcxx/include/__type_traits/reference_constructs_from_temporary.h
+++ b/libcxx/include/__type_traits/reference_constructs_from_temporary.h
@@ -30,14 +30,8 @@ _LIBCPP_NO_SPECIALIZATIONS inline constexpr bool reference_constructs_from_tempo
 
 #endif
 
-#if __has_builtin(__reference_constructs_from_temporary)
 template <class _Tp, class _Up>
 inline const bool __reference_constructs_from_temporary_v = __reference_constructs_from_temporary(_Tp, _Up);
-#else
-// TODO(LLVM 22): Remove this as all supported compilers should have __reference_constructs_from_temporary implemented.
-template <class _Tp, class _Up>
-inline const bool __reference_constructs_from_temporary_v = __reference_binds_to_temporary(_Tp, _Up);
-#endif
 
 _LIBCPP_END_NAMESPACE_STD
 
diff --git a/libcxx/include/forward_list b/libcxx/include/forward_list
index df7da20cfb611..88d863f494e86 100644
--- a/libcxx/include/forward_list
+++ b/libcxx/include/forward_list
@@ -284,17 +284,6 @@ struct __forward_node_traits {
   typedef _NodePtr __node_pointer;
   typedef __forward_begin_node<_NodePtr> __begin_node;
   typedef __rebind_pointer_t<_NodePtr, __begin_node> __begin_node_pointer;
-
-// TODO(LLVM 22): Remove this check
-#  ifndef _LIBCPP_ABI_FORWARD_LIST_REMOVE_NODE_POINTER_UB
-  static_assert(sizeof(__begin_node_pointer) == sizeof(__node_pointer) && _LIBCPP_ALIGNOF(__begin_node_pointer) ==
-                    _LIBCPP_ALIGNOF(__node_pointer),
-                "It looks like you are using std::forward_list with a fancy pointer type that thas a different "
-                "representation depending on whether it points to a forward_list base pointer or a forward_list node "
-                "pointer (both of which are implementation details of the standard library). This means that your ABI "
-                "is being broken between LLVM 19 and LLVM 20. If you don't care about your ABI being broken, define "
-                "the _LIBCPP_ABI_FORWARD_LIST_REMOVE_NODE_POINTER_UB macro to silence this diagnostic.");
-#  endif
 };
 
 template <class _NodePtr>
diff --git a/libcxx/include/list b/libcxx/include/list
index c5c2a8508999c..0ff85d2ebcb86 100644
--- a/libcxx/include/list
+++ b/libcxx/include/list
@@ -276,17 +276,6 @@ template <class _Tp, class _VoidPtr>
 struct __list_node_pointer_traits {
   typedef __rebind_pointer_t<_VoidPtr, __list_node<_Tp, _VoidPtr> > __node_pointer;
   typedef __rebind_pointer_t<_VoidPtr, __list_node_base<_Tp, _VoidPtr> > __base_pointer;
-
-// TODO(LLVM 22): Remove this check
-#  ifndef _LIBCPP_ABI_LIST_REMOVE_NODE_POINTER_UB
-  static_assert(sizeof(__node_pointer) == sizeof(__node_pointer) && _LIBCPP_ALIGNOF(__base_pointer) ==
-                    _LIBCPP_ALIGNOF(__node_pointer),
-                "It looks like you are using std::list with a fancy pointer type that thas a different representation "
-                "depending on whether it points to a list base pointer or a list node pointer (both of which are "
-                "implementation details of the standard library). This means that your ABI is being broken between "
-                "LLVM 19 and LLVM 20. If you don't care about your ABI being broken, define the "
-                "_LIBCPP_ABI_LIST_REMOVE_NODE_POINTER_UB macro to silence this diagnostic.");
-#  endif
 };
 
 template <class _Tp, class _VoidPtr>
diff --git a/libcxx/include/tuple b/libcxx/include/tuple
index 5f3bb72e0678b..466f501b5f4f8 100644
--- a/libcxx/include/tuple
+++ b/libcxx/include/tuple
@@ -301,7 +301,7 @@ _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX14 bool __tuple_compare_equal(c
 template <class _Tp, class _Up, class _IndexSeq = make_index_sequence<tuple_size_v<_Tp>>>
 inline constexpr bool __can_tuple_compare_equal = false;
 
-// TODO(LLVM 22): Remove `tuple_size_v<_Tp> == tuple_size_v<_Up>` here once once LLVM-20 support ends
+// TODO(LLVM 23): Remove `tuple_size_v<_Tp> == tuple_size_v<_Up>` here once once LLVM-20 support ends
 // because the resolution of CWG2369 landed in LLVM-21.
 template <class _Tp, class _Up, size_t... _Is>
   requires(tuple_size_v<_Tp> == tuple_size_v<_Up>)
@@ -328,7 +328,7 @@ concept __tuple_like_no_tuple = __tuple_like<_Tp> && !__is_tuple_v<_Tp>;
 template <class _Tp, class _Up, class _IndexSeq>
 struct __tuple_common_comparison_category_impl {};
 
-// TODO(LLVM 22): Remove `tuple_size_v<_Tp> == tuple_size_v<_Up>` here once once LLVM-20 support ends
+// TODO(LLVM 23): Remove `tuple_size_v<_Tp> == tuple_size_v<_Up>` here once once LLVM-20 support ends
 // because the resolution of CWG2369 landed in LLVM-21.
 template <class _Tp, class _Up, size_t... _Is>
   requires(tuple_size_v<_Tp> == tuple_size_v<_Up>) && requires {
diff --git a/libcxx/include/variant b/libcxx/include/variant
index 9beef146f203c..8e958581a6b07 100644
--- a/libcxx/include/variant
+++ b/libcxx/include/variant
@@ -1299,7 +1299,7 @@ public:
     __impl_.__swap(__that.__impl_);
   }
 
-#    if _LIBCPP_STD_VER >= 26 && _LIBCPP_HAS_EXPLICIT_THIS_PARAMETER
+#    if _LIBCPP_STD_VER >= 26
   // Helper class to implement [variant.visit]/10
   //   Constraints: The call to visit does not use an explicit template-argument-list
   //   that begins with a type template-argument.
diff --git a/libcxx/test/libcxx-03/utilities/meta/is_referenceable.compile.pass.cpp b/libcxx/test/libcxx-03/utilities/meta/is_referenceable.compile.pass.cpp
index 093bbae289723..f39d1a5da41af 100644
--- a/libcxx/test/libcxx-03/utilities/meta/is_referenceable.compile.pass.cpp
+++ b/libcxx/test/libcxx-03/utilities/meta/is_referenceable.compile.pass.cpp
@@ -7,7 +7,7 @@
 //===----------------------------------------------------------------------===//
 //
 
-// __is_referenceable_v<Tp>
+// __libcpp_is_referenceable<Tp>
 //
 // [defns.referenceable] defines "a referenceable type" as:
 // An object type, a function type that does not have cv-qualifiers
diff --git a/libcxx/test/libcxx/numerics/c.math/constexpr-cxx23-clang.pass.cpp b/libcxx/test/libcxx/numerics/c.math/constexpr-cxx23-clang.pass.cpp
index 3f17f21e8c108..20887b8cf2678 100644
--- a/libcxx/test/libcxx/numerics/c.math/constexpr-cxx23-clang.pass.cpp
+++ b/libcxx/test/libcxx/numerics/c.math/constexpr-cxx23-clang.pass.cpp
@@ -220,16 +220,9 @@ int main(int, char**) {
   ASSERT_CONSTEXPR_CXX23(std::isnormal(-1.0) == 1);
   ASSERT_CONSTEXPR_CXX23(std::isnormal(-1.0L) == 1);
 
-// TODO(LLVM 22): Remove `__has_constexpr_builtin` conditional once support for Clang 19 is dropped.
-#if !__has_constexpr_builtin(__builtin_signbit)
-  ASSERT_NOT_CONSTEXPR_CXX23(std::signbit(-1.0f) == 1);
-  ASSERT_NOT_CONSTEXPR_CXX23(std::signbit(-1.0) == 1);
-  ASSERT_NOT_CONSTEXPR_CXX23(std::signbit(-1.0L) == 1);
-#else
   ASSERT_CONSTEXPR_CXX23(std::signbit(-1.0f) == 1);
   ASSERT_CONSTEXPR_CXX23(std::signbit(-1.0) == 1);
   ASSERT_CONSTEXPR_CXX23(std::signbit(-1.0L) == 1);
-#endif
 
   ASSERT_NOT_CONSTEXPR_CXX23(std::isgreater(-1.0f, 0.0f) == 0);
   ASSERT_NOT_CONSTEXPR_CXX23(std::isgreater(-1.0, 0.0) == 0);
diff --git a/libcxx/test/libcxx/utilities/expected/expected.expected/transform_error.mandates.verify.cpp b/libcxx/test/libcxx/utilities/expected/expected.expected/transform_error.mandates.verify.cpp
index 09ebd0069b3a9..3e9bdd98cd394 100644
--- a/libcxx/test/libcxx/utilities/expected/expected.expected/transform_error.mandates.verify.cpp
+++ b/libcxx/test/libcxx/utilities/expected/expected.expected/transform_error.mandates.verify.cpp
@@ -8,15 +8,6 @@
 
 // UNSUPPORTED: c++03, c++11, c++14, c++17, c++20
 
-// With clang-cl, some warnings have a 'which is a Microsoft extension' suffix
-// which break the tests. But #102851 will turn it into an error, making the test pass.
-// However, upstream libcxx buildbots do not build clang from source while testing, so
-// this tests still expected to fail on these bots.
-//
-// TODO(LLVM 22): Remove '0-1' from 'expected-error-re@*:* 0-1 {{union member {{.*}} has reference type {{.*}}}}'
-// and remove 'expected-warning-re@*:* 0-1 {{union member {{.*}} has reference type {{.*}}, which is a Microsoft extension}}'
-// once LLVM 22 releases. See https://llvm.org/PR104885.
-
 // Test the mandates
 
 // template<class F> constexpr auto transform_error(F&& f) &;
@@ -55,41 +46,39 @@ void test() {
   {
     std::expected<int, int> e;
     e.transform_error(return_unexpected<int&>); // expected-error-re@*:* {{static assertion failed {{.*}}The result of {{.*}} must be a valid template argument for unexpected}}
-    // expected-error-re@*:* 0-1 {{no matching constructor for initialization of{{.*}}}}
     // expected-error-re@*:* {{static assertion failed {{.*}}[expected.object.general] A program that instantiates the definition of template expected<T, E> for {{.*}} is ill-formed.}}
-    // expected-error-re@*:* 0-1 {{union member {{.*}} has reference type {{.*}}}}
+    // expected-error-re@*:* {{union member {{.*}} has reference type {{.*}}}}
 
     e.transform_error(return_no_object<int&>); // expected-error-re@*:* {{static assertion failed {{.*}}The result of {{.*}} must be a valid template argument for unexpected}}
-    // expected-error-re@*:* 0-1 {{no matching constructor for initialization of{{.*}}}}
+    // expected-error-re@*:* {{no matching constructor for initialization of{{.*}}}}
     // expected-error-re@*:* {{static assertion failed {{.*}}[expected.object.general] A program that instantiates the definition of template expected<T, E> for {{.*}} is ill-formed.}}
-    // expected-warning-re@*:* 0-1 {{union member {{.*}} has reference type {{.*}}, which is a Microsoft extension}}
   }
 
   // Test const& overload
   {
     const std::expected<int, int> e;
     e.transform_error(return_unexpected<const int &>); // expected-error-re@*:* {{static assertion failed {{.*}}The result of {{.*}} must be a valid template argument for unexpected}}
-    // expected-error-re@*:* 0-2 {{no matching constructor for initialization of{{.*}}}}
+    // expected-error-re@*:* {{no matching constructor for initialization of{{.*}}}}
     e.transform_error(return_no_object<const int &>); // expected-error-re@*:* {{static assertion failed {{.*}}The result of {{.*}} must be a valid template argument for unexpected}}
-    // expected-error-re@*:* 0-2 {{no matching constructor for initialization of{{.*}}}}
+    // expected-error-re@*:* {{no matching constructor for initialization of{{.*}}}}
   }
 
   // Test && overload
   {
     std::expected<int, int> e;
     std::move(e).transform_error(return_unexpected<int&&>); // expected-error-re@*:* {{static assertion failed {{.*}}The result of {{.*}} must be a valid template argument for unexpected}}
-    // expected-error-re@*:* 0-2 {{no matching constructor for initialization of{{.*}}}}
+    // expected-error-re@*:* {{no matching constructor for initialization of{{.*}}}}
     std::move(e).transform_error(return_no_object<int&&>); // expected-error-re@*:* {{static assertion failed {{.*}}The result of {{.*}} must be a valid template argument for unexpected}}
-    // expected-error-re@*:* 0-2 {{no matching constructor for initialization of{{.*}}}}
+    // expected-error-re@*:* {{no matching constructor for initialization of{{.*}}}}
   }
 
   // Test const&& overload
   {
     const std::expected<int, int> e;
     std::move(e).transform_error(return_unexpected<const int&&>); // expected-error-re@*:* {{static assertion failed {{.*}}The result of {{.*}} must be a valid template argument for unexpected}}
-    // expected-error-re@*:* 0-2 {{no matching constructor for initialization of{{.*}}}}
+    // expected-error-re@*:* {{no matching constructor for initialization of{{.*}}}}
     std::move(e).transform_error(return_no_object<const int&&>); // expected-error-re@*:* {{static assertion failed {{.*}}The result of {{.*}} must be a valid template argument for unexpected}}
-    // expected-error-re@*:* 0-2 {{no matching constructor for initialization of{{.*}}}}
+    // expected-error-re@*:* {{no matching constructor for initialization of{{.*}}}}
   }
 }
 // clang-format on
diff --git a/libcxx/test/libcxx/utilities/expected/expected.void/transform_error.mandates.verify.cpp b/libcxx/test/libcxx/utilities/expected/expected.void/transform_error.mandates.verify.cpp
index 9fd7452af64fb..c5acc27af03ea 100644
--- a/libcxx/test/libcxx/utilities/expected/expected.void/transform_error.mandates.verify.cpp
+++ b/libcxx/test/libcxx/utilities/expected/expected.void/transform_error.mandates.verify.cpp
@@ -8,16 +8,6 @@
 
 // UNSUPPORTED: c++03, c++11, c++14, c++17, c++20
 
-// With clang-cl, some warnings have a 'which is a Microsoft extension' suffix
-// which break the tests. But #102851 will turn it into an error, making the test pass.
-// However, upstream libcxx buildbots do not build clang from source while testing, so
-// this tests still expected to fail on these bots.
-//
-// TODO(LLVM 22): Remove '0-1' from 'expected-error-re@*:* 0-1 {{union member {{.*}} has reference type {{.*}}}}'
-// and remove 'expected-warning-re@*:* 0-1 {{union member {{.*}} has reference type {{.*}}, which is a Microsoft extension}}'
-// and remove 'expected-error-re@*:* 0-1 {{call to deleted constructor of {{.*}}}}'
-// once LLVM 22 releases. See See https://llvm.org/PR104885.
-
 // Test the mandates
 
 // template<class F> constexpr auto transform_error(F&& f) &;
@@ -56,43 +46,36 @@ void test() {
   {
     std::expected<void, int> e;
     e.transform_error(return_unexpected<int&>); // expected-error-re@*:* {{static assertion failed {{.*}}The result of {{.*}} must be a valid template argument for unexpected}}
-    // expected-error-re@*:* 0-1 {{no matching constructor for initialization of{{.*}}}}
+    // expected-error-re@*:* {{no matching constructor for initialization of{{.*}}}}
     // expected-error-re@*:* {{static assertion failed {{.*}}A program that instantiates expected<T, E> with a E that is not a valid argument for unexpected<E> is ill-formed}}
-    // expected-error-re@*:* 0-1 {{call to deleted constructor of {{.*}}}}
-    // expected-error-re@*:* 0-1 {{union member {{.*}} has reference type {{.*}}}}
+    // expected-error-re@*:* {{union member {{.*}} has reference type {{.*}}}}
 
     e.transform_error(return_no_object<int&>); // expected-error-re@*:* {{static assertion failed {{.*}}The result of {{.*}} must be a valid template argument for unexpected}}
-    // expected-error-re@*:* 0-1 {{no matching constructor for initialization of{{.*}}}}
+    // expected-error-re@*:* {{no matching constructor for initialization of{{.*}}}}
     // expected-error-re@*:* {{static assertion failed {{.*}}A program that instantiates expected<T, E> with a E that is not a valid argument for unexpected<E> is ill-formed}}
-    // expected-warning-re@*:* 0-1 {{union member {{.*}} has reference type {{.*}}, which is a Microsoft extension}}
   }
 
   // Test const& overload
   {
     const std::expected<void, int> e;
     e.transform_error(return_unexpected<const int &>); // expected-error-re@*:* {{static assertion failed {{.*}}The result of {{.*}} must be a valid template argument for unexpected}}
-    // expected-error-re@*:* 0-1 {{no matching constructor for initialization of{{.*}}}}
+    // expected-error-re@*:* {{no matching constructor for initialization of{{.*}}}}
     e.transform_error(return_no_object<const int &>); // expected-error-re@*:* {{static assertion failed {{.*}}The result of {{.*}} must be a valid template argument for unexpected}}
-    // expected-error-re@*:* 0-1 {{no matching constructor for initialization of{{.*}}}}
-    // expected-error-re@*:* 0-1 {{call to deleted constructor of {{.*}}}}
+    // expected-error-re@*:* {{no matching constructor for initialization of{{.*}}}}
   }
 
   // Test && overload
   {
     std::expected<void, int> e;
     std::move(e).transform_error(return_unexpected<int&&>); // expected-error-re@*:* {{static assertion failed {{.*}}The result of {{.*}} must be a valid template argument for unexpected}}
-    // expected-error-re@*:* 0-1 {{no matching constructor for initialization of{{.*}}}}
     std::move(e).transform_error(return_no_object<int&&>); // expected-error-re@*:* {{static assertion failed {{.*}}The result of {{.*}} must be a valid template argument for unexpected}}
-    // expected-error-re@*:* 0-1 {{no matching constructor for initialization of{{.*}}}}
   }
 
   // Test const&& overload
   {
     const std::expected<void, int> e;
     std::move(e).transform_error(return_unexpected<const int&&>); // expected-error-re@*:* {{static assertion failed {{.*}}The result of {{.*}} must be a valid template argument for unexpected}}
-    // expected-error-re@*:* 0-1 {{no matching constructor for initialization of{{.*}}}}
     std::move(e).transform_error(return_no_object<const int&&>); // expected-error-re@*:* {{static assertion failed {{.*}}The result of {{.*}} must be a valid template argument for unexpected}}
-    // expected-error-re@*:* 0-1 {{no matching constructor for initialization of{{.*}}}}
   }
 }
 // clang-format on
diff --git a/libcxx/test/std/utilities/format/format.arguments/format.arg/visit.pass.cpp b/libcxx/test/std/utilities/format/format.arguments/format.arg/visit.pass.cpp
index 20e0a5ed66bd0..68fe8b6de41d6 100644
--- a/libcxx/test/std/utilities/format/format.arguments/format.arg/visit.pass.cpp
+++ b/libcxx/test/std/utilities/format/format.arguments/format.arg/visit.pass.cpp
@@ -8,8 +8,6 @@
 
 // UNSUPPORTED: c++03, c++11, c++14, c++17, c++20, c++23
 // UNSUPPORTED: GCC-ALWAYS_INLINE-FIXME
-// The tested functionality needs deducing this.
-// XFAIL: apple-clang
 
 // <format>
 
diff --git a/libcxx/test/std/utilities/format/format.arguments/format.arg/visit.return_type.pass.cpp b/libcxx/test/std/utilities/format/format.arguments/format.arg/visit.return_type.pass.cpp
index 8a79dd4d50f20..4ae63e896caed 100644
--- a/libcxx/test/std/utilities/format/format.arguments/format.arg/visit.return_type.pass.cpp
+++ b/libcxx/test/std/utilities/format/format.arguments/format.arg/visit.return_type.pass.cpp
@@ -8,8 +8,6 @@
 
 // UNSUPPORTED: c++03, c++11, c++14, c++17, c++20, c++23
 // UNSUPPORTED: GCC-ALWAYS_INLINE-FIXME
-// The tested functionality needs deducing this.
-// XFAIL: apple-clang
 
 // <format>
 
diff --git a/libcxx/test/std/utilities/format/format.arguments/format.arg/visit_format_arg.deprecated.verify.cpp b/libcxx/test/std/utilities/format/format.arguments/format.arg/visit_format_arg.deprecated.verify.cpp
index 146ceba58872e..77df72d3c4c6c 100644
--- a/libcxx/test/std/utilities/format/format.arguments/format.arg/visit_format_arg.deprecated.verify.cpp
+++ b/libcxx/test/std/utilities/format/format.arguments/format.arg/visit_format_arg.deprecated.verify.cpp
@@ -8,7 +8,6 @@
 
 // UNSUPPORTED: c++03, c++11, c++14, c++17, c++20, c++23
 // UNSUPPORTED: GCC-ALWAYS_INLINE-FIXME
-// XFAIL: apple-clang
 
 // <format>
 
diff --git a/libcxx/test/std/utilities/format/format.arguments/format.arg/visit_format_arg.pass.cpp b/libcxx/test/std/utilities/format/format.arguments/format.arg/visit_format_arg.pass.cpp
index d99675a71f321..9b7c8a7f4f8b4 100644
--- a/libcxx/test/std/utilities/format/format.arguments/format.arg/visit_format_arg.pass.cpp
+++ b/libcxx/test/std/utilities/format/format.arguments/format.arg/visit_format_arg.pass.cpp
@@ -9,6 +9,8 @@
 // UNSUPPORTED: c++03, c++11, c++14, c++17
 // UNSUPPORTED: GCC-ALWAYS_INLINE-FIXME
 
+// ADDITIONAL_COMPILE_FLAGS: -D_LIBCPP_DISABLE_DEPRECATION_WARNINGS
+
 // <format>
 
 // template<class Visitor, class Context>
@@ -25,10 +27,6 @@
 #include "make_string.h"
 #include "min_allocator.h"
 
-#if TEST_STD_VER >= 26 && defined(TEST_HAS_EXPLICIT_THIS_PARAMETER)
-TEST_CLANG_DIAGNOSTIC_IGNORED("-Wdeprecated-declarations")
-#endif
-
 template <class Context, class To, class From>
 void test(From value) {
   auto store = std::make_format_args<Context>(value);
diff --git a/libcxx/test/std/utilities/format/format.arguments/format.args/get.pass.cpp b/libcxx/test/std/utilities/format/format.arguments/format.args/get.pass.cpp
index c7dd82d726b3a..cbddc4f437a53 100644
--- a/libcxx/test/std/utilities/format/format.arguments/format.args/get.pass.cpp
+++ b/libcxx/test/std/utilities/format/format.arguments/format.args/get.pass.cpp
@@ -32,7 +32,7 @@ void test(From value) {
     else
       assert(false);
   };
-#if TEST_STD_VER >= 26 && defined(TEST_HAS_EXPLICIT_THIS_PARAMETER)
+#if TEST_STD_VER >= 26
   format_args.get(0).visit(visitor);
 #else
   std::visit_format_arg(visitor, format_args.get(0));
@@ -47,7 +47,7 @@ void test_handle(T value) {
   std::basic_format_args<Context> format_args{store};
 
   auto visitor = [](auto a) { assert((std::is_same_v<decltype(a), typename std::basic_format_arg<Context>::handle>)); };
-#if TEST_STD_VER >= 26 && defined(TEST_HAS_EXPLICIT_THIS_PARAMETER)
+#if TEST_STD_VER >= 26
   format_args.get(0).visit(visitor);
 #else
   std::visit_format_arg(visitor, format_args.get(0));
@@ -73,7 +73,7 @@ void test_string_view(From value) {
     else
       assert(false);
   };
-#if TEST_STD_VER >= 26 && defined(TEST_HAS_EXPLICIT_THIS_PARAMETER)
+#if TEST_STD_VER >= 26
   format_args.get(0).visit(visitor);
 #else
   std::visit_format_arg(visitor, format_args.get(0));
diff --git a/libcxx/test/std/utilities/tuple/tuple.tuple/tuple.cnstr/PR20855_tuple_ref_binding_diagnostics.pass.cpp b/libcxx/test/std/utilities/tuple/tuple.tuple/tuple.cnstr/PR20855_tuple_ref_binding_diagnostics.pass.cpp
index d78de0eec8e53..0f6a6734264c3 100644
--- a/libcxx/test/std/utilities/tuple/tuple.tuple/tuple.cnstr/PR20855_tuple_ref_binding_diagnostics.pass.cpp
+++ b/libcxx/test/std/utilities/tuple/tuple.tuple/tuple.cnstr/PR20855_tuple_ref_binding_diagnostics.pass.cpp
@@ -16,17 +16,6 @@
 #include <tuple>
 #include <string>
 #include <cassert>
-#include "test_macros.h"
-
-#if TEST_HAS_BUILTIN(__reference_constructs_from_temporary)
-#  define ASSERT_REFERENCE_BINDS_TEMPORARY(...) static_assert(__reference_constructs_from_temporary(__VA_ARGS__), "")
-#  define ASSERT_NOT_REFERENCE_BINDS_TEMPORARY(...)                                                                    \
-    static_assert(!__reference_constructs_from_temporary(__VA_ARGS__), "")
-#else
-// TODO(LLVM 22): Remove this as all support compilers should have __reference_constructs_from_temporary implemented.
-#  define ASSERT_REFERENCE_BINDS_TEMPORARY(...) static_assert(__reference_binds_to_temporary(__VA_ARGS__), "")
-#  define ASSERT_NOT_REFERENCE_BINDS_TEMPORARY(...) static_assert(!__reference_binds_to_temporary(__VA_ARGS__), "")
-#endif
 
 template <class Tp>
 struct ConvertsTo {
@@ -42,17 +31,6 @@ struct ConvertsTo {
 struct Base {};
 struct Derived : Base {};
 
-
-static_assert(std::is_same<decltype("abc"), decltype(("abc"))>::value, "");
-ASSERT_REFERENCE_BINDS_TEMPORARY(std::string const&, decltype("abc"));
-ASSERT_REFERENCE_BINDS_TEMPORARY(std::string const&, decltype(("abc")));
-ASSERT_REFERENCE_BINDS_TEMPORARY(std::string const&, const char*&&);
-
-ASSERT_NOT_REFERENCE_BINDS_TEMPORARY(int&, const ConvertsTo<int&>&);
-ASSERT_NOT_REFERENCE_BINDS_TEMPORARY(const int&, ConvertsTo<int&>&);
-ASSERT_NOT_REFERENCE_BINDS_TEMPORARY(Base&, Derived&);
-
-
 static_assert(std::is_constructible<int&, std::reference_wrapper<int>>::value, "");
 static_assert(std::is_constructible<int const&, std::reference_wrapper<int>>::value, "");
 
diff --git a/libcxx/test/std/utilities/variant/variant.visit.member/robust_against_adl.pass.cpp b/libcxx/test/std/utilities/variant/variant.visit.member/robust_against_adl.pass.cpp
index 7be7c7ff9122b..38cf34a9c699c 100644
--- a/libcxx/test/std/utilities/variant/variant.visit.member/robust_against_adl.pass.cpp
+++ b/libcxx/test/std/utilities/variant/variant.visit.member/robust_against_adl.pass.cpp
@@ -7,7 +7,6 @@
 //===----------------------------------------------------------------------===//
 
 // UNSUPPORTED: c++03, c++11, c++14, c++17, c++20, c++23
-// XFAIL: apple-clang
 
 // <variant>
 
diff --git a/libcxx/test/std/utilities/variant/variant.visit.member/visit.pass.cpp b/libcxx/test/std/utilities/variant/variant.visit.member/visit.pass.cpp
index f68112d30fc35..aeb1297c136ae 100644
--- a/libcxx/test/std/utilities/variant/variant.visit.member/visit.pass.cpp
+++ b/libcxx/test/std/utilities/variant/variant.visit.member/visit.pass.cpp
@@ -7,8 +7,6 @@
 //===----------------------------------------------------------------------===//
 
 // UNSUPPORTED: c++03, c++11, c++14, c++17, c++20, c++23
-// The tested functionality needs deducing this.
-// XFAIL: apple-clang
 
 // <variant>
 
diff --git a/libcxx/test/std/utilities/variant/variant.visit.member/visit_return_type.pass.cpp b/libcxx/test/std/utilities/variant/variant.visit.member/visit_return_type.pass.cpp
index 90320ae518c34..7ca05908ab340 100644
--- a/libcxx/test/std/utilities/variant/variant.visit.member/visit_return_type.pass.cpp
+++ b/libcxx/test/std/utilities/variant/variant.visit.member/visit_return_type.pass.cpp
@@ -7,8 +7,6 @@
 //===----------------------------------------------------------------------===//
 
 // UNSUPPORTED: c++03, c++11, c++14, c++17, c++20, c++23
-// The tested functionality needs deducing this.
-// XFAIL: apple-clang
 
 // <variant>
 
diff --git a/libcxx/test/support/test_basic_format_arg.h b/libcxx/test/support/test_basic_format_arg.h
index f51f6e97cbed0..99cd558c3c5bf 100644
--- a/libcxx/test/support/test_basic_format_arg.h
+++ b/libcxx/test/support/test_basic_format_arg.h
@@ -21,7 +21,7 @@ bool test_basic_format_arg(std::basic_format_arg<Context> arg, T expected) {
     else
       return false;
   };
-#if TEST_STD_VER >= 26 && defined(TEST_HAS_EXPLICIT_THIS_PARAMETER)
+#if TEST_STD_VER >= 26
   return arg.visit(std::move(visitor));
 #else
   return std::visit_format_arg(std::move(visitor), arg);
diff --git a/libcxx/test/support/test_macros.h b/libcxx/test/support/test_macros.h
index c4e1600572456..8d88d6fad7d0b 100644
--- a/libcxx/test/support/test_macros.h
+++ b/libcxx/test/support/test_macros.h
@@ -531,13 +531,6 @@ inline Tp const& DoNotOptimize(Tp const& value) {
 #  define TEST_IF_AIX(arg_true, arg_false) arg_false
 #endif
 
-// Clang-18 has support for deducing this, but it does not set the FTM.
-#ifdef _LIBCPP_USE_FROZEN_CXX03_HEADERS
-// This is a C++20 featue, so we don't care whether the compiler could support it
-#elif defined(_LIBCPP_VERSION) && _LIBCPP_HAS_EXPLICIT_THIS_PARAMETER
-#  define TEST_HAS_EXPLICIT_THIS_PARAMETER
-#endif
-
 // Placement `operator new`/`operator new[]` are not yet constexpr in C++26
 // when using MS ABI, because they are from <vcruntime_new.h>.
 #if defined(__cpp_lib_constexpr_new) && __cpp_lib_constexpr_new >= 202406L