diff --git a/clang-tools-extra/clang-tidy/utils/HeaderFileExtensionsUtils.cpp b/clang-tools-extra/clang-tidy/utils/HeaderFileExtensionsUtils.cpp
diff --git a/clang-tools-extra/clang-tidy/utils/HeaderFileExtensionsUtils.h b/clang-tools-extra/clang-tidy/utils/HeaderFileExtensionsUtils.h
diff --git a/clang-tools-extra/clang-tidy/utils/HeaderGuard.cpp b/clang-tools-extra/clang-tidy/utils/HeaderGuard.cpp
@@ -273,13 +273,13 @@ void HeaderGuardCheck::registerPPCallbacks(const SourceManager &SM,
 }
 
 bool HeaderGuardCheck::shouldSuggestEndifComment(StringRef FileName) {
-  return utils::isHeaderFileExtension(FileName, HeaderFileExtensions);
+  return utils::isFileExtension(FileName, HeaderFileExtensions);
 }
 
 bool HeaderGuardCheck::shouldFixHeaderGuard(StringRef FileName) { return true; }
 
 bool HeaderGuardCheck::shouldSuggestToAddHeaderGuard(StringRef FileName) {
-  return utils::isHeaderFileExtension(FileName, HeaderFileExtensions);
+  return utils::isFileExtension(FileName, HeaderFileExtensions);
 }
 
 std::string HeaderGuardCheck::formatEndIf(StringRef HeaderGuard) {

diff --git a/clang-tools-extra/clang-tidy/utils/HeaderGuard.h b/clang-tools-extra/clang-tidy/utils/HeaderGuard.h
@@ -10,27 +10,29 @@
 #define LLVM_CLANG_TOOLS_EXTRA_CLANG_TIDY_UTILS_HEADERGUARD_H
 
 #include "../ClangTidy.h"
-#include "../utils/HeaderFileExtensionsUtils.h"
+#include "../utils/FileExtensionsUtils.h"
 
 namespace clang {
 namespace tidy {
 namespace utils {
 
 /// Finds and fixes header guards.
 /// The check supports these options:
-///   - `HeaderFileExtensions`: a comma-separated list of filename extensions of
-///     header files (The filename extension should not contain "." prefix).
-///     ",h,hh,hpp,hxx" by default.
+///   - `HeaderFileExtensions`: a semicolon-separated list of filename
+///     extensions of header files (The filename extension should not contain
+///     "." prefix). ";h;hh;hpp;hxx" by default.
+///
 ///     For extension-less header files, using an empty string or leaving an
-///     empty string between "," if there are other filename extensions.
+///     empty string between ";" if there are other filename extensions.
 class HeaderGuardCheck : public ClangTidyCheck {
 public:
   HeaderGuardCheck(StringRef Name, ClangTidyContext *Context)
       : ClangTidyCheck(Name, Context),
         RawStringHeaderFileExtensions(Options.getLocalOrGlobal(
             "HeaderFileExtensions", utils::defaultHeaderFileExtensions())) {
-    utils::parseHeaderFileExtensions(RawStringHeaderFileExtensions,
-                                     HeaderFileExtensions, ',');
+    utils::parseFileExtensions(RawStringHeaderFileExtensions,
+                               HeaderFileExtensions,
+                               utils::defaultFileExtensionDelimiters());
   }
   void registerPPCallbacks(const SourceManager &SM, Preprocessor *PP,
                            Preprocessor *ModuleExpanderPP) override;
@@ -54,7 +56,7 @@ class HeaderGuardCheck : public ClangTidyCheck {
 
 private:
   std::string RawStringHeaderFileExtensions;
-  utils::HeaderFileExtensionsSet HeaderFileExtensions;
+  utils::FileExtensionsSet HeaderFileExtensions;
 };
 
 } // namespace utils

diff --git a/clang-tools-extra/docs/ReleaseNotes.rst b/clang-tools-extra/docs/ReleaseNotes.rst
@@ -125,6 +125,11 @@ Changes in existing checks
   check now detects in class initializers and constructor initializers which
   are deemed to be redundant.
 
+- Checks supporting the ``HeaderFileExtensions`` flag now support ``;`` as a
+  delimiter in addition to ``,``, with the latter being deprecated as of this
+  release. This simplifies how one specifies the options on the command line:
+  ``--config="{CheckOptions: [{ key: HeaderFileExtensions, value: h;;hpp;hxx }]}"``
+
 Renamed checks
 ^^^^^^^^^^^^^^