diff --git a/libc/utils/CMakeLists.txt b/libc/utils/CMakeLists.txt
--- a/libc/utils/CMakeLists.txt
+++ b/libc/utils/CMakeLists.txt
@@ -1,5 +1,6 @@
 add_subdirectory(CPP)
 add_subdirectory(HdrGen)
+add_subdirectory(LibcTidy)
 add_subdirectory(MPFRWrapper)
 add_subdirectory(testutils)
 add_subdirectory(UnitTest)
diff --git a/libc/utils/HdrGen/PublicAPICommand.h b/libc/utils/HdrGen/PublicAPICommand.h
--- a/libc/utils/HdrGen/PublicAPICommand.h
+++ b/libc/utils/HdrGen/PublicAPICommand.h
@@ -12,6 +12,7 @@
 #include "Command.h"
 
 #include "llvm/ADT/StringRef.h"
+#include "llvm/TableGen/Record.h"
 
 #include <string>
 #include <unordered_map>
@@ -38,4 +39,15 @@
 
 } // namespace llvm_libc
 
+inline bool isa(llvm::Record *Def, llvm::Record *TypeClass) {
+  llvm::RecordRecTy *RecordType = Def->getType();
+  llvm::ArrayRef<llvm::Record *> Classes = RecordType->getClasses();
+  // We want exact types. That is, we don't want the classes listed in
+  // spec.td to be subclassed. Hence, we do not want the record |Def|
+  // to be of more than one class type.
+  if (Classes.size() != 1)
+    return false;
+  return Classes[0] == TypeClass;
+}
+
 #endif // LLVM_LIBC_UTILS_HDRGEN_PUBLICAPICOMMAND_H
diff --git a/libc/utils/HdrGen/PublicAPICommand.cpp b/libc/utils/HdrGen/PublicAPICommand.cpp
--- a/libc/utils/HdrGen/PublicAPICommand.cpp
+++ b/libc/utils/HdrGen/PublicAPICommand.cpp
@@ -12,7 +12,6 @@
 #include "llvm/ADT/StringRef.h"
 #include "llvm/Support/SourceMgr.h"
 #include "llvm/TableGen/Error.h"
-#include "llvm/TableGen/Record.h"
 
 static const char NamedTypeClassName[] = "NamedType";
 static const char PtrTypeClassName[] = "PtrType";
@@ -23,17 +22,6 @@
 static const char StandardSpecClassName[] = "StandardSpec";
 static const char PublicAPIClassName[] = "PublicAPI";
 
-static bool isa(llvm::Record *Def, llvm::Record *TypeClass) {
-  llvm::RecordRecTy *RecordType = Def->getType();
-  llvm::ArrayRef<llvm::Record *> Classes = RecordType->getClasses();
-  // We want exact types. That is, we don't want the classes listed in
-  // spec.td to be subclassed. Hence, we do not want the record |Def|
-  // to be of more than one class type..
-  if (Classes.size() != 1)
-    return false;
-  return Classes[0] == TypeClass;
-}
-
 // Text blocks for macro definitions and type decls can be indented to
 // suit the surrounding tablegen listing. We need to dedent such blocks
 // before writing them out.
diff --git a/libc/utils/LibcTidy/CMakeLists.txt b/libc/utils/LibcTidy/CMakeLists.txt
new file mode 100644
--- /dev/null
+++ b/libc/utils/LibcTidy/CMakeLists.txt
@@ -0,0 +1,18 @@
+set(LLVM_LINK_COMPONENTS support TableGen)
+include(${PROJECT_SOURCE_DIR}/../clang/cmake/modules/AddClang.cmake)
+
+include_directories(${PROJECT_BINARY_DIR}/tools/clang/include/)
+include_directories(${PROJECT_SOURCE_DIR}/../clang/include/)
+
+add_clang_executable(libc-tidy
+  LibcTidyTool.cpp
+  Main.cpp
+  TableGenUtil.cpp)
+
+target_link_libraries(libc-tidy
+  PRIVATE
+  clangTooling
+  clangBasic
+  clangASTMatchers)
+
+add_subdirectory(tests)
diff --git a/libc/utils/LibcTidy/EntrypointNameCheck.h b/libc/utils/LibcTidy/EntrypointNameCheck.h
new file mode 100644
--- /dev/null
+++ b/libc/utils/LibcTidy/EntrypointNameCheck.h
@@ -0,0 +1,72 @@
+//===-- EntrypointNameCheck.h -----------------------------------*- C++ -*-===//
+//
+// 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
+//
+//===----------------------------------------------------------------------===//
+
+#ifndef LLVM_LIBC_UTILS_LIBCTIDY_ENTRYPOINTNAMECHECK_H
+#define LLVM_LIBC_UTILS_LIBCTIDY_ENTRYPOINTNAMECHECK_H
+
+#include "clang/Lex/MacroArgs.h"
+#include "clang/Lex/PPCallbacks.h"
+
+#include "LibcTidyTool.h"
+
+using namespace clang;
+using namespace clang::ast_matchers;
+
+class EntrypointPPCallback : public PPCallbacks {
+public:
+  EntrypointPPCallback(LibcTidyCheck &check, MatchFinder &finder)
+      : check(check), finder(finder) {}
+
+  void MacroExpands(const Token &macroNameTok, const MacroDefinition &,
+                    SourceRange, const MacroArgs *args) override {
+    if (macroNameTok.getIdentifierInfo()->getName() != "LLVM_LIBC_ENTRYPOINT")
+      return;
+
+    // Get the name of the function passed to macro and register a matcher.
+    StringRef Name = args->getUnexpArgument(0)->getIdentifierInfo()->getName();
+    finder.addMatcher(functionDecl(hasName(Name)).bind("libc_entry"), &check);
+  }
+
+private:
+  LibcTidyCheck &check;
+  MatchFinder &finder;
+};
+
+class EntrypointNameCheck : public LibcTidyCheck {
+public:
+  EntrypointNameCheck(const llvm::StringSet<> &publicFunctions)
+      : publicFunctions(publicFunctions) {}
+
+  void registerPPCallbacks(Preprocessor &PP, MatchFinder &finder) override {
+    PP.addPPCallbacks(std::make_unique<EntrypointPPCallback>(*this, finder));
+  }
+
+  void run(const MatchFinder::MatchResult &result) override {
+    const auto *funcDecl = result.Nodes.getNodeAs<FunctionDecl>("libc_entry");
+    SourceLocation loc = funcDecl->getLocation();
+
+    // Ignore declarations from header files.
+    if (!result.SourceManager->isInMainFile(loc))
+      return;
+
+    StringRef funcName = funcDecl->getName();
+    if (publicFunctions.count(funcName) != 0)
+      return;
+
+    DiagnosticsEngine &DE = result.Context->getDiagnostics();
+    const unsigned ID =
+        DE.getCustomDiagID(DiagnosticsEngine::Error,
+                           "Entrypoint %0 is not a public libc function.");
+    DE.Report(loc, ID).AddString(funcName);
+  }
+
+private:
+  const llvm::StringSet<> &publicFunctions;
+};
+
+#endif // LLVM_LIBC_UTILS_LIBCTIDY_ENTRYPOINTNAMECHECK_H
diff --git a/libc/utils/LibcTidy/LibcTidyTool.h b/libc/utils/LibcTidy/LibcTidyTool.h
new file mode 100644
--- /dev/null
+++ b/libc/utils/LibcTidy/LibcTidyTool.h
@@ -0,0 +1,38 @@
+//===-- LibcTidyTool.h ------------------------------------------*- C++ -*-===//
+//
+// 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
+//
+//===----------------------------------------------------------------------===//
+
+#ifndef LLVM_LIBC_UTILS_LIBCTIDY_TOOL_H
+#define LLVM_LIBC_UTILS_LIBCTIDY_TOOL_H
+
+#include "clang/ASTMatchers/ASTMatchFinder.h"
+#include "clang/Frontend/FrontendActions.h"
+#include "clang/Tooling/Tooling.h"
+
+#include "llvm/ADT/StringSet.h"
+
+class LibcTidyCheck : public clang::ast_matchers::MatchFinder::MatchCallback {
+public:
+  virtual void registerPPCallbacks(clang::Preprocessor &PP,
+                                   clang::ast_matchers::MatchFinder &finder){};
+  virtual void registerMatchers(clang::ast_matchers::MatchFinder &finder){};
+};
+
+class LibcTidyActionFactory : public clang::tooling::FrontendActionFactory {
+public:
+  LibcTidyActionFactory(clang::ast_matchers::MatchFinder &finder,
+                        std::vector<std::unique_ptr<LibcTidyCheck>> &checks)
+      : finder(finder), checks(checks) {}
+
+  std::unique_ptr<clang::FrontendAction> create() override;
+
+private:
+  clang::ast_matchers::MatchFinder &finder;
+  std::vector<std::unique_ptr<LibcTidyCheck>> &checks;
+};
+
+#endif // LLVM_LIBC_UTILS_LIBCTIDY_TOOL_H
diff --git a/libc/utils/LibcTidy/LibcTidyTool.cpp b/libc/utils/LibcTidy/LibcTidyTool.cpp
new file mode 100644
--- /dev/null
+++ b/libc/utils/LibcTidy/LibcTidyTool.cpp
@@ -0,0 +1,42 @@
+//===-- LibcTidyTool.cpp --------------------------------------------------===//
+//
+// 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
+//
+//===----------------------------------------------------------------------===//
+
+#include "clang/ASTMatchers/ASTMatchers.h"
+#include "clang/Frontend/CompilerInstance.h"
+
+#include "llvm/Support/Debug.h"
+#include "llvm/Support/raw_ostream.h"
+
+#include "LibcTidyTool.h"
+
+using namespace clang;
+using namespace clang::ast_matchers;
+
+class LibcTidyAction : public ASTFrontendAction {
+public:
+  LibcTidyAction(MatchFinder &finder,
+                 std::vector<std::unique_ptr<LibcTidyCheck>> &checks)
+      : finder(finder), checks(checks) {}
+
+  std::unique_ptr<ASTConsumer> CreateASTConsumer(CompilerInstance &compiler,
+                                                 llvm::StringRef) override {
+    Preprocessor &PP = compiler.getPreprocessor();
+    for (auto &check : checks)
+      check->registerPPCallbacks(PP, finder);
+
+    return finder.newASTConsumer();
+  }
+
+private:
+  MatchFinder &finder;
+  std::vector<std::unique_ptr<LibcTidyCheck>> &checks;
+};
+
+std::unique_ptr<FrontendAction> LibcTidyActionFactory::create() {
+  return std::make_unique<LibcTidyAction>(finder, checks);
+}
diff --git a/libc/utils/LibcTidy/Main.cpp b/libc/utils/LibcTidy/Main.cpp
new file mode 100644
--- /dev/null
+++ b/libc/utils/LibcTidy/Main.cpp
@@ -0,0 +1,71 @@
+//===-- Main.cpp ----------------------------------------------------------===//
+//
+// 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
+//
+//===----------------------------------------------------------------------===//
+
+#include "clang/Tooling/CommonOptionsParser.h"
+#include "clang/Tooling/Tooling.h"
+
+#include "llvm/Support/CommandLine.h"
+#include "llvm/TableGen/Main.h"
+
+#include "EntrypointNameCheck.h"
+#include "LibcTidyTool.h"
+#include "TableGenUtil.h"
+
+using namespace clang;
+
+static llvm::cl::OptionCategory LibCTidyCategory("libc-tidy options");
+
+static llvm::cl::opt<std::string> TableGenFilePathOption(
+    "tablegen-filepath",
+    llvm::cl::desc(
+        "The filepath to the '.td' file containing libc public api functions"),
+    llvm::cl::Required, llvm::cl::cat(LibCTidyCategory));
+
+static llvm::cl::opt<std::string> TableGenIncludeDirOption(
+    "tablegen-includedir",
+    llvm::cl::desc("The include dir to pass to tablegen."), llvm::cl::Required,
+    llvm::cl::cat(LibCTidyCategory));
+
+llvm::StringSet<> publicFunctions;
+
+bool TidyTableGenMain(llvm::raw_ostream &OS, llvm::RecordKeeper &records) {
+  publicFunctions = getAllLibcFunctions(records);
+  return false;
+}
+
+int main(int argc, const char **argv) {
+  // Both clang tooling and TableGen expect positional arguments. So instead we
+  // remove and manually provide the arguments below for TableGenMain.
+  llvm::cl::Option *tblGenFileOpt =
+      llvm::cl::TopLevelSubCommand->PositionalOpts.pop_back_val();
+  llvm::cl::Option *tblGenIncludeOpt =
+      llvm::cl::TopLevelSubCommand->OptionsMap["I"];
+
+  tooling::CommonOptionsParser OptionsParser(argc, argv, LibCTidyCategory);
+  tooling::ClangTool Tool(OptionsParser.getCompilations(),
+                          OptionsParser.getSourcePathList());
+
+  // Manually pass our option values to TableGenMain's options.
+  llvm::cl::ProvidePositionalOption(tblGenFileOpt, TableGenFilePathOption, 0);
+  llvm::cl::ProvidePositionalOption(tblGenIncludeOpt, TableGenIncludeDirOption,
+                                    0);
+
+  TableGenMain(argv[0], &TidyTableGenMain);
+
+  MatchFinder finder;
+
+  // Checks
+  std::vector<std::unique_ptr<LibcTidyCheck>> checks;
+  checks.emplace_back(std::make_unique<EntrypointNameCheck>(publicFunctions));
+
+  for (auto &check : checks)
+    check->registerMatchers(finder);
+
+  LibcTidyActionFactory factory(finder, checks);
+  return Tool.run(&factory);
+}
diff --git a/libc/utils/LibcTidy/TableGenUtil.h b/libc/utils/LibcTidy/TableGenUtil.h
new file mode 100644
--- /dev/null
+++ b/libc/utils/LibcTidy/TableGenUtil.h
@@ -0,0 +1,18 @@
+//===-- TableGenUtil.h ------------------------------------------*- C++ -*-===//
+//
+// 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
+//
+//===----------------------------------------------------------------------===//
+
+#ifndef LLVM_LIBC_UTILS_LIBCTIDY_TABLEGENUTIL_H
+#define LLVM_LIBC_UTILS_LIBCTIDY_TABLEGENUTIL_H
+
+#include "llvm/ADT/StringSet.h"
+#include "llvm/Support/Error.h"
+#include "llvm/TableGen/Record.h"
+
+llvm::StringSet<> getAllLibcFunctions(llvm::RecordKeeper &records);
+
+#endif // LLVM_LIBC_UTILS_LIBCTIDY_TABLEGENUTIL_H
diff --git a/libc/utils/LibcTidy/TableGenUtil.cpp b/libc/utils/LibcTidy/TableGenUtil.cpp
new file mode 100644
--- /dev/null
+++ b/libc/utils/LibcTidy/TableGenUtil.cpp
@@ -0,0 +1,26 @@
+//===-- TableGenUtil.cpp --------------------------------------------------===//
+//
+// 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
+//
+//===----------------------------------------------------------------------===//
+
+#include "TableGenUtil.h"
+#include "../HdrGen/PublicAPICommand.h"
+
+llvm::StringSet<> getAllLibcFunctions(llvm::RecordKeeper &records) {
+  llvm::StringSet<> funcNames;
+
+  llvm::Record *publicAPIClass = records.getClass("PublicAPI");
+  const auto &defsMap = records.getDefs();
+  for (const auto &pair : defsMap) {
+    llvm::Record *def = pair.second.get();
+    if (!isa(def, publicAPIClass))
+      continue;
+
+    auto functionNameList = def->getValueAsListOfStrings("Functions");
+    funcNames.insert(functionNameList.begin(), functionNameList.end());
+  }
+  return funcNames;
+}
diff --git a/libc/utils/LibcTidy/tests/.clang-format b/libc/utils/LibcTidy/tests/.clang-format
new file mode 100644
--- /dev/null
+++ b/libc/utils/LibcTidy/tests/.clang-format
@@ -0,0 +1,2 @@
+BasedOnStyle: LLVM
+ColumnLimit: 0
diff --git a/libc/utils/LibcTidy/tests/CMakeLists.txt b/libc/utils/LibcTidy/tests/CMakeLists.txt
new file mode 100644
--- /dev/null
+++ b/libc/utils/LibcTidy/tests/CMakeLists.txt
@@ -0,0 +1,8 @@
+add_lit_testsuite(check-libc-tidy "Libc-Tidy Regression Tests."
+  ${CMAKE_CURRENT_BINARY_DIR}
+  DEPENDS libc-tidy FileCheck not
+  EXCLUDE_FROM_CHECK_ALL)
+
+configure_lit_site_cfg(
+  ${CMAKE_CURRENT_SOURCE_DIR}/lit.site.cfg.in
+  ${CMAKE_CURRENT_BINARY_DIR}/lit.site.cfg)
diff --git a/libc/utils/LibcTidy/tests/EntrypointNameTest.cpp b/libc/utils/LibcTidy/tests/EntrypointNameTest.cpp
new file mode 100644
--- /dev/null
+++ b/libc/utils/LibcTidy/tests/EntrypointNameTest.cpp
@@ -0,0 +1,21 @@
+// RUN: not libc-tidy %s --tablegen-filepath "%S/mock_api.td" \
+// RUN: --tablegen-includedir "%S/../../../" -- 2>&1 | FileCheck %s
+
+#define LLVM_LIBC_ENTRYPOINT(name) name
+#define SOMETHING_ELSE(name) name
+
+namespace __llvm_libc {
+
+// Entrypoint is valid if the function is a public libc function.
+void LLVM_LIBC_ENTRYPOINT(libc_api_func)(char *param) {}
+// CHECK-NOT: error: Entrypoint libc_api_func is not a public libc function.
+
+// Functions defined with different macros are ignored.
+void SOMETHING_ELSE(different_macro)(char *param) {}
+// CHECK-NOT: error: Entrypoint different_macro is not a public libc function.
+
+// Entrypoint is invalid if the function is not a public libc function.
+void LLVM_LIBC_ENTRYPOINT(non_api_func)(char *param) {}
+// CHECK: :[[@LINE-1]]:27: error: Entrypoint non_api_func is not a public libc function.
+
+} // namespace __llvm_libc
diff --git a/libc/utils/LibcTidy/tests/lit.site.cfg.in b/libc/utils/LibcTidy/tests/lit.site.cfg.in
new file mode 100644
--- /dev/null
+++ b/libc/utils/LibcTidy/tests/lit.site.cfg.in
@@ -0,0 +1,8 @@
+import os
+import lit.formats
+
+config.name = 'libc-tidy'
+config.test_format = lit.formats.ShTest()
+config.test_source_root = "@CMAKE_CURRENT_SOURCE_DIR@"
+config.suffixes = ['.cpp']
+config.environment['PATH'] = "@LLVM_TOOLS_DIR@"
diff --git a/libc/utils/LibcTidy/tests/mock_api.td b/libc/utils/LibcTidy/tests/mock_api.td
new file mode 100644
--- /dev/null
+++ b/libc/utils/LibcTidy/tests/mock_api.td
@@ -0,0 +1,7 @@
+include "config/public_api.td"
+
+def FakeAPI : PublicAPI<"fakeapi.h"> {
+  let Functions = [
+    "libc_api_func",
+  ];
+}