diff --git a/clang/docs/ReleaseNotes.rst b/clang/docs/ReleaseNotes.rst
index 9bedbf7a1e7621..7fb21dbadea005 100644
--- a/clang/docs/ReleaseNotes.rst
+++ b/clang/docs/ReleaseNotes.rst
@@ -469,6 +469,7 @@ C2x Feature Support
   support for functions without prototypes, which no longer exist in C2x.
 - Implemented `WG14 N2841 No function declarators without prototypes <https://www9.open-std.org/jtc1/sc22/wg14/www/docs/n2841.htm>`_
   and `WG14 N2432 Remove support for function definitions with identifier lists <https://www9.open-std.org/jtc1/sc22/wg14/www/docs/n2432.pdf>`_.
+- Implemented `WG14 N2836 Identifier Syntax using Unicode Standard Annex 31 <https://www.open-std.org/jtc1/sc22/wg14/www/docs/n2836.pdf>`_.
 
 C++ Language Changes in Clang
 -----------------------------
diff --git a/clang/lib/Lex/Lexer.cpp b/clang/lib/Lex/Lexer.cpp
index b3aac9df65465c..a4cff403e739c6 100644
--- a/clang/lib/Lex/Lexer.cpp
+++ b/clang/lib/Lex/Lexer.cpp
@@ -1462,11 +1462,11 @@ static bool isAllowedIDChar(uint32_t C, const LangOptions &LangOpts) {
     return false;
   } else if (LangOpts.DollarIdents && '$' == C) {
     return true;
-  } else if (LangOpts.CPlusPlus) {
+  } else if (LangOpts.CPlusPlus || LangOpts.C2x) {
     // A non-leading codepoint must have the XID_Continue property.
     // XIDContinueRanges doesn't contains characters also in XIDStartRanges,
     // so we need to check both tables.
-    // '_' doesn't have the XID_Continue property but is allowed in C++.
+    // '_' doesn't have the XID_Continue property but is allowed in C and C++.
     static const llvm::sys::UnicodeCharSet XIDStartChars(XIDStartRanges);
     static const llvm::sys::UnicodeCharSet XIDContinueChars(XIDContinueRanges);
     return C == '_' || XIDStartChars.contains(C) ||
@@ -1486,7 +1486,7 @@ static bool isAllowedInitiallyIDChar(uint32_t C, const LangOptions &LangOpts) {
   if (LangOpts.AsmPreprocessor) {
     return false;
   }
-  if (LangOpts.CPlusPlus) {
+  if (LangOpts.CPlusPlus || LangOpts.C2x) {
     static const llvm::sys::UnicodeCharSet XIDStartChars(XIDStartRanges);
     // '_' doesn't have the XID_Start property but is allowed in C++.
     return C == '_' || XIDStartChars.contains(C);
diff --git a/clang/test/Lexer/unicode.c b/clang/test/Lexer/unicode.c
index efbd63fb00630d..8d5295ef338b4d 100644
--- a/clang/test/Lexer/unicode.c
+++ b/clang/test/Lexer/unicode.c
@@ -1,5 +1,6 @@
 // RUN: %clang_cc1 -fsyntax-only -verify -x c -std=c11 %s
-// RUN: %clang_cc1 -fsyntax-only -verify -x c++ -std=c++11 %s
+// RUN: %clang_cc1 -fsyntax-only -verify=expected,c2x -x c -std=c2x %s
+// RUN: %clang_cc1 -fsyntax-only -verify=expected,cxx -x c++ -std=c++11 %s
 // RUN: %clang_cc1 -std=c99 -E -DPP_ONLY=1 %s | FileCheck %s --strict-whitespace
 // RUN: %clang_cc1 -E -DPP_ONLY=1 %s | FileCheck %s --strict-whitespace
 
@@ -31,7 +32,7 @@ CHECK : The preprocessor should not complain about Unicode characters like ©.
 extern int X\UAAAAAAAA; // expected-error {{not allowed in an identifier}}
 int Y = '\UAAAAAAAA'; // expected-error {{invalid universal character}}
 
-#ifdef __cplusplus
+#if defined(__cplusplus) || (defined(__STDC_VERSION__) && __STDC_VERSION__ >= 202000L)
 
 extern int ༀ;
 extern int 𑩐;
@@ -46,7 +47,8 @@ extern int _\N{TANGSALETTERGA}; // expected-error {{'TANGSALETTERGA' is not a va
 
 
 // This character doesn't have the XID_Start property
-extern int  \U00016AC0; // TANGSA DIGIT ZERO  // expected-error {{expected unqualified-id}}
+extern int  \U00016AC0; // TANGSA DIGIT ZERO  // cxx-error {{expected unqualified-id}} \
+                                              // c2x-error {{expected identifier or '('}}
 
 extern int 🌹; // expected-error {{unexpected character <U+1F339>}} \
                   expected-warning {{declaration does not declare anything}}
diff --git a/clang/www/c_status.html b/clang/www/c_status.html
index 17d18d8724f8d6..f3076d345237a1 100644
--- a/clang/www/c_status.html
+++ b/clang/www/c_status.html
@@ -1024,7 +1024,7 @@ <h2 id="c2x">C2x implementation status</h2>
     <tr>
       <td>Identifier Syntax using Unicode Standard Annex 31</td>
       <td><a href="https://www.open-std.org/jtc1/sc22/wg14/www/docs/n2836.pdf">N2836</a></td>
-      <td class="none" align="center">No</td>
+      <td class="unreleased" align="center">Clang 15</td>
     </tr>
     <tr>
       <td>No function declarators without prototypes</td>