diff --git a/clang/docs/ReleaseNotes.rst b/clang/docs/ReleaseNotes.rst
index 3645dff2e6fe8..29794f27d3005 100644
--- a/clang/docs/ReleaseNotes.rst
+++ b/clang/docs/ReleaseNotes.rst
@@ -272,6 +272,8 @@ C++23 Feature Support
 
 - Extend lifetime of temporaries in mem-default-init for P2718R0. Clang now fully
   supports `P2718R0 Lifetime extension in range-based for loops <https://wg21.link/P2718R0>`_.
+  
+- ``__cpp_explicit_this_parameter`` is now defined. (#GH82780)
 
 C++20 Feature Support
 ^^^^^^^^^^^^^^^^^^^^^
diff --git a/clang/lib/Frontend/InitPreprocessor.cpp b/clang/lib/Frontend/InitPreprocessor.cpp
index e20feedb840b5..29723b573e771 100644
--- a/clang/lib/Frontend/InitPreprocessor.cpp
+++ b/clang/lib/Frontend/InitPreprocessor.cpp
@@ -752,6 +752,7 @@ static void InitializeCPlusPlusFeatureTestMacros(const LangOptions &LangOpts,
     Builder.defineMacro("__cpp_if_consteval", "202106L");
     Builder.defineMacro("__cpp_multidimensional_subscript", "202211L");
     Builder.defineMacro("__cpp_auto_cast", "202110L");
+    Builder.defineMacro("__cpp_explicit_this_parameter", "202110L");
   }
 
   // We provide those C++23 features as extensions in earlier language modes, so
diff --git a/clang/test/Lexer/cxx-features.cpp b/clang/test/Lexer/cxx-features.cpp
index 5b88e00b71508..3a60318d3f231 100644
--- a/clang/test/Lexer/cxx-features.cpp
+++ b/clang/test/Lexer/cxx-features.cpp
@@ -81,7 +81,7 @@
 #error "wrong value for __cpp_named_character_escapes"
 #endif
 
-#if check(explicit_this_parameter, 0, 0, 0, 0, 0, 0, 0)
+#if check(explicit_this_parameter, 0, 0, 0, 0, 0, 202110L, 202110L)
 #error "wrong value for __cpp_explicit_this_parameter"
 #endif