diff --git a/clang-tools-extra/clang-tidy/check_suffix.py b/clang-tools-extra/clang-tidy/check_suffix.py
new file mode 100644
index 0000000000000..37b35844f24e9
--- /dev/null
+++ b/clang-tools-extra/clang-tidy/check_suffix.py
@@ -0,0 +1,138 @@
+#!/usr/bin/env python3
+#
+# ===-----------------------------------------------------------------------===#
+#
+# Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+# See https://llvm.org/LICENSE.txt for license information.
+# SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+#
+# ===-----------------------------------------------------------------------===#
+
+import os
+import sys
+
+# This script verifies that all clang-tidy checks' header/source filenames end
+# with the "Check" suffix.
+
+FOLDERS = [
+    "abseil",
+    "altera",
+    "android",
+    "boost",
+    "bugprone",
+    "cert",
+    "concurrency",
+    "cppcoreguidelines",
+    "custom",
+    "darwin",
+    "fuchsia",
+    "google",
+    "hicpp",
+    "linuxkernel",
+    "llvm",
+    "llvmlibc",
+    "misc",
+    "modernize",
+    "mpi",
+    "objc",
+    "openmp",
+    "performance",
+    "portability",
+    "readability",
+    "zircon",
+]
+
+GLOBAL_IGNORES = {
+    "CMakeLists.txt",
+}
+
+# Per-folder ignores. Paths listed here are matched by basename; entries that
+# refer to directories should be skipped from traversal.
+PER_FOLDER_IGNORES = {
+    "abseil": {"AbseilMatcher.h", "DurationRewriter.h", "DurationRewriter.cpp"},
+    "cert": {"LICENSE.TXT"},
+    "hicpp": {"LICENSE.TXT"},
+    "llvmlibc": {"NamespaceConstants.h"},
+    "misc": {"ConfusableTable"},
+    "modernize": {
+        "IntegralLiteralExpressionMatcher.h",
+        "IntegralLiteralExpressionMatcher.cpp",
+        "LoopConvertUtils.h",
+        "LoopConvertUtils.cpp",
+    },
+}
+
+
+def get_module_name(folder: str) -> str:
+    """Return the tidy module filename for a folder."""
+    special_cases = {
+        "hicpp": "HICPPTidyModule.cpp",
+        "cppcoreguidelines": "CppCoreGuidelinesTidyModule.cpp",
+        "linuxkernel": "LinuxKernelTidyModule.cpp",
+        "llvmlibc": "LLVMLibcTidyModule.cpp",
+        "mpi": "MPITidyModule.cpp",
+        "objc": "ObjCTidyModule.cpp",
+        "openmp": "OpenMPTidyModule.cpp",
+        "llvm": "LLVMTidyModule.cpp",
+        "cert": "CERTTidyModule.cpp",
+    }
+    return special_cases.get(folder, f"{folder.capitalize()}TidyModule.cpp")
+
+
+def should_skip(folder: str, path_basename: str) -> bool:
+    """Whether a file/dir should be ignored for a folder."""
+    if path_basename in GLOBAL_IGNORES:
+        return True
+    ignores = PER_FOLDER_IGNORES.get(folder, set())
+    return path_basename in ignores
+
+
+def iter_candidate_files(clang_tidy_path: str):
+    """Yield all .h/.cpp files to check."""
+    for folder in FOLDERS:
+        folder_path = os.path.join(clang_tidy_path, folder)
+        if not os.path.isdir(folder_path):
+            continue
+
+        module_file = get_module_name(folder)
+
+        for root, dirs, files in os.walk(folder_path):
+            dirs[:] = [d for d in dirs if not should_skip(folder, d)]
+
+            for name in files:
+                if name == module_file or should_skip(folder, name):
+                    continue
+                if not (name.endswith(".h") or name.endswith(".cpp")):
+                    continue
+                rel = os.path.relpath(os.path.join(root, name), clang_tidy_path)
+                yield rel
+
+
+def find_missing_suffix_files(clang_tidy_path: str) -> list:
+    """Return a list of .h/.cpp files for checks missing the 'Check' suffix."""
+    missing: list = []
+    for rel in iter_candidate_files(clang_tidy_path):
+        base = os.path.splitext(os.path.basename(rel))[0]
+        if not base.endswith("Check"):
+            missing.append(rel)
+    return missing
+
+
+def main() -> None:
+    clang_tidy_path = os.path.dirname(os.path.abspath(__file__))
+    missing_files = find_missing_suffix_files(clang_tidy_path)
+
+    if missing_files:
+        print("Found checks missing the 'Check' suffix:")
+        for file_path in sorted(missing_files):
+            print(file_path)
+    else:
+        print("No checks found missing the 'Check' suffix.")
+
+    if missing_files:
+        sys.exit(1)
+    sys.exit(0)
+
+
+if __name__ == "__main__":
+    main()
diff --git a/clang-tools-extra/test/clang-tidy/infrastructure/check-suffix.test b/clang-tools-extra/test/clang-tidy/infrastructure/check-suffix.test
new file mode 100644
index 0000000000000..445d682aae005
--- /dev/null
+++ b/clang-tools-extra/test/clang-tidy/infrastructure/check-suffix.test
@@ -0,0 +1 @@
+// RUN: %python %S/../../../clang-tidy/check_suffix.py
diff --git a/clang-tools-extra/test/lit.cfg.py b/clang-tools-extra/test/lit.cfg.py
index c1da37d61bd61..c39ea29329674 100644
--- a/clang-tools-extra/test/lit.cfg.py
+++ b/clang-tools-extra/test/lit.cfg.py
@@ -57,6 +57,7 @@
 if config.clang_tidy_custom_check:
     config.available_features.add("custom-check")
 python_exec = shlex.quote(config.python_executable)
+config.substitutions.append(("%python", python_exec))
 check_clang_tidy = os.path.join(
     config.test_source_root, "clang-tidy", "check_clang_tidy.py"
 )