diff --git a/clang/include/clang/Basic/DiagnosticSemaKinds.td b/clang/include/clang/Basic/DiagnosticSemaKinds.td
index 7df963f7ba059..b496900fac06e 100644
--- a/clang/include/clang/Basic/DiagnosticSemaKinds.td
+++ b/clang/include/clang/Basic/DiagnosticSemaKinds.td
@@ -9431,15 +9431,15 @@ def ext_defaulted_comparison_constexpr_mismatch : Extension<
   "three-way comparison operator}0 that is "
   "declared %select{constexpr|consteval}2 but"
   "%select{|for which the corresponding implicit 'operator==' }0 "
-  "invokes a non-constexpr comparison function is a C++2b extension">,
-  InGroup<DiagGroup<"c++2b-default-comp-relaxed-constexpr">>;
-def warn_cxx2b_compat_defaulted_comparison_constexpr_mismatch : Warning<
+  "invokes a non-constexpr comparison function is a C++23 extension">,
+  InGroup<DiagGroup<"c++23-default-comp-relaxed-constexpr">>;
+def warn_cxx23_compat_defaulted_comparison_constexpr_mismatch : Warning<
   "defaulted definition of %select{%sub{select_defaulted_comparison_kind}1|"
   "three-way comparison operator}0 that is "
   "declared %select{constexpr|consteval}2 but"
   "%select{|for which the corresponding implicit 'operator==' }0 "
   "invokes a non-constexpr comparison function is incompatible with C++ "
-  "standards before C++2b">,
+  "standards before C++23">,
   InGroup<CXXPre23Compat>, DefaultIgnore;
 def note_defaulted_comparison_not_constexpr : Note<
   "non-constexpr comparison function would be used to compare "
diff --git a/clang/lib/Sema/SemaDeclCXX.cpp b/clang/lib/Sema/SemaDeclCXX.cpp
index 208e34a40e488..dcb3e676b0ba4 100644
--- a/clang/lib/Sema/SemaDeclCXX.cpp
+++ b/clang/lib/Sema/SemaDeclCXX.cpp
@@ -8830,7 +8830,7 @@ bool Sema::CheckExplicitlyDefaultedComparison(Scope *S, FunctionDecl *FD,
         !Info.Constexpr) {
       Diag(FD->getBeginLoc(),
            getLangOpts().CPlusPlus23
-               ? diag::warn_cxx2b_compat_defaulted_comparison_constexpr_mismatch
+               ? diag::warn_cxx23_compat_defaulted_comparison_constexpr_mismatch
                : diag::ext_defaulted_comparison_constexpr_mismatch)
           << FD->isImplicit() << (int)DCK << FD->isConsteval();
       DefaultedComparisonAnalyzer(*this, RD, FD, DCK,
diff --git a/clang/test/CXX/class/class.compare/class.compare.default/p3.cpp b/clang/test/CXX/class/class.compare/class.compare.default/p3.cpp
index a64b8b895f61d..166bd97e2731c 100644
--- a/clang/test/CXX/class/class.compare/class.compare.default/p3.cpp
+++ b/clang/test/CXX/class/class.compare/class.compare.default/p3.cpp
@@ -2,7 +2,7 @@
 // Also covers modifications made by P2448R2 and extension warnings
 
 // RUN: %clang_cc1 -std=c++2a -verify %s
-// RUN: %clang_cc1 -std=c++2a -Wc++2b-default-comp-relaxed-constexpr -verify=expected,extension %s
+// RUN: %clang_cc1 -std=c++2a -Wc++23-default-comp-relaxed-constexpr -verify=expected,extension %s
 
 namespace std {
   struct strong_ordering {
@@ -131,10 +131,10 @@ struct E {
   A a;
   C c; // extension-note 2{{non-constexpr comparison function would be used to compare member 'c'}}
   A b;
-  friend constexpr bool operator==(const E&, const E&) = default; // extension-warning {{declared constexpr but invokes a non-constexpr comparison function is a C++2b extension}}
+  friend constexpr bool operator==(const E&, const E&) = default; // extension-warning {{declared constexpr but invokes a non-constexpr comparison function is a C++23 extension}}
   friend constexpr bool operator!=(const E&, const E&) = default;
 
-  friend constexpr std::strong_ordering operator<=>(const E&, const E&) = default; // extension-warning {{declared constexpr but invokes a non-constexpr comparison function is a C++2b extension}}
+  friend constexpr std::strong_ordering operator<=>(const E&, const E&) = default; // extension-warning {{declared constexpr but invokes a non-constexpr comparison function is a C++23 extension}}
   friend constexpr bool operator<(const E&, const E&) = default;
   friend constexpr bool operator<=(const E&, const E&) = default;
   friend constexpr bool operator>(const E&, const E&) = default;
@@ -142,10 +142,10 @@ struct E {
 };
 
 struct E2 : A, C { // extension-note 2{{non-constexpr comparison function would be used to compare base class 'C'}}
-  friend constexpr bool operator==(const E2&, const E2&) = default; // extension-warning {{declared constexpr but invokes a non-constexpr comparison function is a C++2b extension}}
+  friend constexpr bool operator==(const E2&, const E2&) = default; // extension-warning {{declared constexpr but invokes a non-constexpr comparison function is a C++23 extension}}
   friend constexpr bool operator!=(const E2&, const E2&) = default;
 
-  friend constexpr std::strong_ordering operator<=>(const E2&, const E2&) = default; // extension-warning {{declared constexpr but invokes a non-constexpr comparison function is a C++2b extension}}
+  friend constexpr std::strong_ordering operator<=>(const E2&, const E2&) = default; // extension-warning {{declared constexpr but invokes a non-constexpr comparison function is a C++23 extension}}
   friend constexpr bool operator<(const E2&, const E2&) = default;
   friend constexpr bool operator<=(const E2&, const E2&) = default;
   friend constexpr bool operator>(const E2&, const E2&) = default;
@@ -154,13 +154,13 @@ struct E2 : A, C { // extension-note 2{{non-constexpr comparison function would
 
 struct F {
   friend bool operator==(const F&, const F&); // extension-note {{non-constexpr comparison function declared here}}
-  friend constexpr bool operator!=(const F&, const F&) = default; // extension-warning {{declared constexpr but invokes a non-constexpr comparison function is a C++2b extension}}
+  friend constexpr bool operator!=(const F&, const F&) = default; // extension-warning {{declared constexpr but invokes a non-constexpr comparison function is a C++23 extension}}
 
   friend std::strong_ordering operator<=>(const F&, const F&); // extension-note 4{{non-constexpr comparison function declared here}}
-  friend constexpr bool operator<(const F&, const F&) = default; // extension-warning {{declared constexpr but invokes a non-constexpr comparison function is a C++2b extension}}
-  friend constexpr bool operator<=(const F&, const F&) = default; // extension-warning {{declared constexpr but invokes a non-constexpr comparison function is a C++2b extension}}
-  friend constexpr bool operator>(const F&, const F&) = default; // extension-warning {{declared constexpr but invokes a non-constexpr comparison function is a C++2b extension}}
-  friend constexpr bool operator>=(const F&, const F&) = default; // extension-warning {{declared constexpr but invokes a non-constexpr comparison function is a C++2b extension}}
+  friend constexpr bool operator<(const F&, const F&) = default; // extension-warning {{declared constexpr but invokes a non-constexpr comparison function is a C++23 extension}}
+  friend constexpr bool operator<=(const F&, const F&) = default; // extension-warning {{declared constexpr but invokes a non-constexpr comparison function is a C++23 extension}}
+  friend constexpr bool operator>(const F&, const F&) = default; // extension-warning {{declared constexpr but invokes a non-constexpr comparison function is a C++23 extension}}
+  friend constexpr bool operator>=(const F&, const F&) = default; // extension-warning {{declared constexpr but invokes a non-constexpr comparison function is a C++23 extension}}
 };
 
 // No implicit 'constexpr' if it's not the first declaration.
diff --git a/clang/test/CXX/class/class.compare/class.compare.default/p4.cpp b/clang/test/CXX/class/class.compare/class.compare.default/p4.cpp
index fdb89f3da5352..fab2abb7dee00 100644
--- a/clang/test/CXX/class/class.compare/class.compare.default/p4.cpp
+++ b/clang/test/CXX/class/class.compare/class.compare.default/p4.cpp
@@ -1,5 +1,5 @@
 // RUN: %clang_cc1 -std=c++2a -verify %s
-// RUN: %clang_cc1 -std=c++2a -Wc++2b-default-comp-relaxed-constexpr -verify=expected,extension %s
+// RUN: %clang_cc1 -std=c++2a -Wc++23-default-comp-relaxed-constexpr -verify=expected,extension %s
 
 // This test is for [class.compare.default]p3 as modified and renumbered to p4
 // by P2002R0.
@@ -84,7 +84,7 @@ struct H {
 
 struct I {
   H h; // extension-note {{non-constexpr comparison function would be used to compare member 'h'}}
-  constexpr std::strong_ordering operator<=>(const I&) const = default; // extension-warning {{implicit 'operator=='  invokes a non-constexpr comparison function is a C++2b extension}}
+  constexpr std::strong_ordering operator<=>(const I&) const = default; // extension-warning {{implicit 'operator=='  invokes a non-constexpr comparison function is a C++23 extension}}
 };
 
 struct J {
@@ -150,7 +150,7 @@ namespace GH61238 {
 template <typename A> struct my_struct {
     A value; // extension-note {{non-constexpr comparison function would be used to compare member 'value'}}
 
-    constexpr friend bool operator==(const my_struct &, const my_struct &) noexcept = default; // extension-warning {{declared constexpr but invokes a non-constexpr comparison function is a C++2b extension}}
+    constexpr friend bool operator==(const my_struct &, const my_struct &) noexcept = default; // extension-warning {{declared constexpr but invokes a non-constexpr comparison function is a C++23 extension}}
 };
 
 struct non_constexpr_type {