Index: clang-tools-extra/clang-tidy/abseil/AbseilTidyModule.cpp
===================================================================
--- clang-tools-extra/clang-tidy/abseil/AbseilTidyModule.cpp
+++ clang-tools-extra/clang-tidy/abseil/AbseilTidyModule.cpp
@@ -20,6 +20,7 @@
 #include "FasterStrsplitDelimiterCheck.h"
 #include "NoInternalDependenciesCheck.h"
 #include "NoNamespaceCheck.h"
+#include "PrefixedThreadAnnotationsCheck.h"
 #include "RedundantStrcatCallsCheck.h"
 #include "StringFindStartswithCheck.h"
 #include "StrCatAppendCheck.h"
@@ -55,6 +56,8 @@
     CheckFactories.registerCheck<NoInternalDependenciesCheck>(
         "abseil-no-internal-dependencies");
     CheckFactories.registerCheck<NoNamespaceCheck>("abseil-no-namespace");
+    CheckFactories.registerCheck<PrefixedThreadAnnotationsCheck>(
+        "abseil-prefixed-thread-annotations");
     CheckFactories.registerCheck<RedundantStrcatCallsCheck>(
         "abseil-redundant-strcat-calls");
     CheckFactories.registerCheck<StrCatAppendCheck>(
Index: clang-tools-extra/clang-tidy/abseil/CMakeLists.txt
===================================================================
--- clang-tools-extra/clang-tidy/abseil/CMakeLists.txt
+++ clang-tools-extra/clang-tidy/abseil/CMakeLists.txt
@@ -14,6 +14,7 @@
   FasterStrsplitDelimiterCheck.cpp
   NoInternalDependenciesCheck.cpp
   NoNamespaceCheck.cpp
+  PrefixedThreadAnnotationsCheck.cpp
   RedundantStrcatCallsCheck.cpp
   StrCatAppendCheck.cpp
   StringFindStartswithCheck.cpp
Index: clang-tools-extra/clang-tidy/abseil/PrefixedThreadAnnotationsCheck.h
===================================================================
--- /dev/null
+++ clang-tools-extra/clang-tidy/abseil/PrefixedThreadAnnotationsCheck.h
@@ -0,0 +1,37 @@
+//===--- PrefixedThreadAnnotationsCheck.h - clang-tidy ----------*- 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_CLANG_TOOLS_EXTRA_CLANG_TIDY_ABSEIL_PREFIXEDTHREADANNOTATIONSCHECK_H
+#define LLVM_CLANG_TOOLS_EXTRA_CLANG_TIDY_ABSEIL_PREFIXEDTHREADANNOTATIONSCHECK_H
+
+#include "../ClangTidyCheck.h"
+#include "clang/Lex/PPCallbacks.h"
+
+namespace clang {
+namespace tidy {
+namespace abseil {
+
+/// This check finds usages of deprecated Abseil thread annotation macros and
+/// migrates them to the new macros that are prefixed with `ABSL_`.
+///
+/// For the user-facing documentation see:
+/// http://clang.llvm.org/extra/clang-tidy/checks/abseil-prefixed-thread-annotations.html
+class PrefixedThreadAnnotationsCheck : public ClangTidyCheck {
+ public:
+  PrefixedThreadAnnotationsCheck(StringRef Name, ClangTidyContext *Context)
+      : ClangTidyCheck(Name, Context) {}
+
+  void registerPPCallbacks(const SourceManager &SM, Preprocessor *PP,
+                           Preprocessor *ModuleExpanderPP) override;
+};
+
+} // namespace abseil
+} // namespace tidy
+} // namespace clang
+
+#endif // LLVM_CLANG_TOOLS_EXTRA_CLANG_TIDY_ABSEIL_PREFIXEDTHREADANNOTATIONSCHECK_H
Index: clang-tools-extra/clang-tidy/abseil/PrefixedThreadAnnotationsCheck.cpp
===================================================================
--- /dev/null
+++ clang-tools-extra/clang-tidy/abseil/PrefixedThreadAnnotationsCheck.cpp
@@ -0,0 +1,58 @@
+//===--- PrefixedThreadAnnotationsCheck.cpp - clang-tidy ------------------===//
+//
+// 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 "PrefixedThreadAnnotationsCheck.h"
+
+namespace clang {
+namespace tidy {
+namespace abseil {
+
+constexpr char kAbseilThreadAnnotationsHeader[] =
+    "absl/base/internal/thread_annotations.h";
+
+namespace {
+
+class PrefixedThreadAnnotationsPPCallbacks : public PPCallbacks {
+ public:
+  PrefixedThreadAnnotationsPPCallbacks(ClangTidyCheck &Check,
+                                       const SourceManager &SM)
+      : Check(Check), SM(SM) {}
+
+  void MacroExpands(const Token &MacroNameTok, const MacroDefinition &MD,
+                    SourceRange Range, const MacroArgs *Args) override;
+
+ private:
+  ClangTidyCheck &Check;
+  const SourceManager &SM;
+};
+
+void PrefixedThreadAnnotationsPPCallbacks::MacroExpands(
+    const Token &MacroNameTok, const MacroDefinition &MD, SourceRange Range,
+    const MacroArgs *Args) {
+  llvm::StringRef actual_header =
+      SM.getFilename(MD.getMacroInfo()->getDefinitionLoc());
+  llvm::StringRef original_header =
+      llvm::StringRef(kAbseilThreadAnnotationsHeader);
+  if (actual_header.endswith(original_header)) {
+    FixItHint hint = FixItHint::CreateInsertion(Range.getBegin(), "ABSL_");
+    Check.diag(Range.getBegin(), "usage of unprefixed thread annotation")
+        << hint;
+  }
+}
+
+}  // End of anonymous namespace.
+
+void PrefixedThreadAnnotationsCheck::registerPPCallbacks(
+    const SourceManager &SM, Preprocessor *PP, Preprocessor *ModuleExpanderPP) {
+  PP->addPPCallbacks(
+      llvm::make_unique<PrefixedThreadAnnotationsPPCallbacks>(*this, SM));
+}
+
+} // namespace abseil
+} // namespace tidy
+} // namespace clang
Index: clang-tools-extra/docs/ReleaseNotes.rst
===================================================================
--- clang-tools-extra/docs/ReleaseNotes.rst
+++ clang-tools-extra/docs/ReleaseNotes.rst
@@ -89,6 +89,12 @@
   Finds and fixes cases where ``absl::Duration`` values are being converted to
   numeric types and back again.
 
+- New :doc:`abseil-prefixed-thread-annotations
+  <clang-tidy/checks/abseil-prefixed-thread-annotations>` check.
+
+  Checks for usages of deprecated Abseil thread annotation macros and
+  migrates them to the new macros that are prefixed with `ABSL_`.
+
 - New :doc:`abseil-time-comparison
   <clang-tidy/checks/abseil-time-comparison>` check.
 
Index: clang-tools-extra/docs/clang-tidy/checks/abseil-prefixed-thread-annotations.rst
===================================================================
--- /dev/null
+++ clang-tools-extra/docs/clang-tidy/checks/abseil-prefixed-thread-annotations.rst
@@ -0,0 +1,28 @@
+.. title:: clang-tidy - abseil-prefixed-thread-annotations
+
+abseil-prefixed-thread-annotations
+==================================
+
+This check finds usages of deprecated Abseil thread annotation macros and
+migrates them to the new macros that are prefixed with `ABSL_`.
+
+Examples:
+
+.. code-block:: c++
+// Original - Usage of deprecated and unprefixed Abseil thread annotations.
+#include "absl/base/thread_annotations.h"
+
+class X {
+  // ...
+  private:
+    absl::Mutex m_;
+    int state_ GUARDED_BY(m_);
+};
+
+// Suggestion - Addition of ABSL_ prefix.
+class X {
+  // ...
+  private:
+    absl::Mutex m_;
+    int state_ ABSL_GUARDED_BY(m_);
+};
Index: clang-tools-extra/docs/clang-tidy/checks/list.rst
===================================================================
--- clang-tools-extra/docs/clang-tidy/checks/list.rst
+++ clang-tools-extra/docs/clang-tidy/checks/list.rst
@@ -15,6 +15,7 @@
    abseil-faster-strsplit-delimiter
    abseil-no-internal-dependencies
    abseil-no-namespace
+   abseil-prefixed-thread-annotations
    abseil-redundant-strcat-calls
    abseil-str-cat-append
    abseil-string-find-startswith
Index: clang-tools-extra/test/clang-tidy/Inputs/absl/base/internal/thread_annotations.h
===================================================================
--- /dev/null
+++ clang-tools-extra/test/clang-tidy/Inputs/absl/base/internal/thread_annotations.h
@@ -0,0 +1 @@
+#define SCOPED_LOCKABLE
Index: clang-tools-extra/test/clang-tidy/Inputs/absl/base/thread_annotations.h
===================================================================
--- /dev/null
+++ clang-tools-extra/test/clang-tidy/Inputs/absl/base/thread_annotations.h
@@ -0,0 +1,3 @@
+#include "absl/base/internal/thread_annotations.h"
+
+#define ABSL_SCOPED_LOCKABLE
Index: clang-tools-extra/test/clang-tidy/abseil-prefixed-thread-annotations.cpp
===================================================================
--- /dev/null
+++ clang-tools-extra/test/clang-tidy/abseil-prefixed-thread-annotations.cpp
@@ -0,0 +1,9 @@
+// RUN: %check_clang_tidy %s abseil-prefixed-thread-annotations %t -- -- -I%S/Inputs
+
+#include "absl/base/thread_annotations.h"
+
+class SCOPED_LOCKABLE X {};
+// CHECK-MESSAGES: :[[@LINE-1]]:7: warning: usage of unprefixed thread annotation [abseil-prefixed-thread-annotations]
+// CHECK-FIXES: class ABSL_SCOPED_LOCKABLE X {};
+
+class ABSL_SCOPED_LOCKABLE Y {};
Index: llvm/utils/gn/secondary/clang-tools-extra/clang-tidy/abseil/BUILD.gn
===================================================================
--- llvm/utils/gn/secondary/clang-tools-extra/clang-tidy/abseil/BUILD.gn
+++ llvm/utils/gn/secondary/clang-tools-extra/clang-tidy/abseil/BUILD.gn
@@ -25,6 +25,7 @@
     "FasterStrsplitDelimiterCheck.cpp",
     "NoInternalDependenciesCheck.cpp",
     "NoNamespaceCheck.cpp",
+    "PrefixedThreadAnnotationsCheck.cpp",
     "RedundantStrcatCallsCheck.cpp",
     "StrCatAppendCheck.cpp",
     "StringFindStartswithCheck.cpp",