Index: clang-tidy/cppcoreguidelines/CMakeLists.txt
===================================================================
--- clang-tidy/cppcoreguidelines/CMakeLists.txt
+++ clang-tidy/cppcoreguidelines/CMakeLists.txt
@@ -2,6 +2,7 @@
 
 add_clang_library(clangTidyCppCoreGuidelinesModule
   CppCoreGuidelinesTidyModule.cpp
+  EnumAllCapsCheck.cpp
   ProBoundsArrayToPointerDecayCheck.cpp
   ProBoundsConstantArrayIndexCheck.cpp
   ProBoundsPointerArithmeticCheck.cpp
Index: clang-tidy/cppcoreguidelines/CppCoreGuidelinesTidyModule.cpp
===================================================================
--- clang-tidy/cppcoreguidelines/CppCoreGuidelinesTidyModule.cpp
+++ clang-tidy/cppcoreguidelines/CppCoreGuidelinesTidyModule.cpp
@@ -11,6 +11,7 @@
 #include "../ClangTidyModule.h"
 #include "../ClangTidyModuleRegistry.h"
 #include "../misc/AssignOperatorSignatureCheck.h"
+#include "EnumAllCapsCheck.h"
 #include "ProBoundsArrayToPointerDecayCheck.h"
 #include "ProBoundsConstantArrayIndexCheck.h"
 #include "ProBoundsPointerArithmeticCheck.h"
@@ -29,6 +30,8 @@
 class CppCoreGuidelinesModule : public ClangTidyModule {
 public:
   void addCheckFactories(ClangTidyCheckFactories &CheckFactories) override {
+    CheckFactories.registerCheck<EnumAllCapsCheck>(
+        "cppcoreguidelines-enum-all-caps");
     CheckFactories.registerCheck<ProBoundsArrayToPointerDecayCheck>(
         "cppcoreguidelines-pro-bounds-array-to-pointer-decay");
     CheckFactories.registerCheck<ProBoundsConstantArrayIndexCheck>(
Index: clang-tidy/cppcoreguidelines/EnumAllCapsCheck.h
===================================================================
--- /dev/null
+++ clang-tidy/cppcoreguidelines/EnumAllCapsCheck.h
@@ -0,0 +1,36 @@
+//===--- EnumAllCapsCheck.h - clang-tidy-------------------------*- C++ -*-===//
+//
+//                     The LLVM Compiler Infrastructure
+//
+// This file is distributed under the University of Illinois Open Source
+// License. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+
+#ifndef LLVM_CLANG_TOOLS_EXTRA_CLANG_TIDY_CPPCOREGUIDELINES_ENUMALLCAPS_H
+#define LLVM_CLANG_TOOLS_EXTRA_CLANG_TIDY_CPPCOREGUIDELINES_ENUMALLCAPS_H
+
+#include "../ClangTidy.h"
+
+namespace clang {
+namespace tidy {
+namespace cppcoreguidelines {
+
+/// This check flags all ALL_CAPS enumerations
+///
+/// For the user-facing documentation see:
+/// http://clang.llvm.org/extra/clang-tidy/checks/cppcoreguidelines-enum-all-caps.html
+class EnumAllCapsCheck : public ClangTidyCheck {
+public:
+  EnumAllCapsCheck(StringRef Name, ClangTidyContext *Context)
+      : ClangTidyCheck(Name, Context) {}
+  void registerMatchers(ast_matchers::MatchFinder *Finder) override;
+  void check(const ast_matchers::MatchFinder::MatchResult &Result) override;
+};
+
+} // namespace cppcoreguidelines
+} // namespace tidy
+} // namespace clang
+
+#endif // LLVM_CLANG_TOOLS_EXTRA_CLANG_TIDY_CPPCOREGUIDELINES_ENUMALLCAPS_H
+
Index: clang-tidy/cppcoreguidelines/EnumAllCapsCheck.cpp
===================================================================
--- /dev/null
+++ clang-tidy/cppcoreguidelines/EnumAllCapsCheck.cpp
@@ -0,0 +1,55 @@
+//===--- EnumAllCapsCheck.cpp - clang-tidy---------------------------------===//
+//
+//                     The LLVM Compiler Infrastructure
+//
+// This file is distributed under the University of Illinois Open Source
+// License. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+
+#include "EnumAllCapsCheck.h"
+#include "clang/AST/ASTContext.h"
+#include "clang/ASTMatchers/ASTMatchFinder.h"
+
+#include <cctype>
+#include <string>
+#include <algorithm>
+
+using namespace clang::ast_matchers;
+
+namespace clang {
+namespace tidy {
+namespace cppcoreguidelines {
+
+void EnumAllCapsCheck::registerMatchers(MatchFinder *Finder) {
+  Finder->addMatcher(enumConstantDecl().bind("enum"), this);
+}
+
+void EnumAllCapsCheck::check(const MatchFinder::MatchResult &Result) {
+  const auto *MatchedDecl = Result.Nodes.getNodeAs<EnumConstantDecl>("enum");
+  unsigned AlphabeticLetters = 0;
+  bool AllCapsed = true;
+  for (auto symbol : MatchedDecl->getName()) {
+    if (std::isalpha(symbol)) {
+      AlphabeticLetters++;
+      if (!std::isupper(symbol)) {
+        AllCapsed = false;
+      }
+    }
+  }
+  if (!AllCapsed) {
+    return;
+  }
+  if (AlphabeticLetters <= 1) {
+    return;
+  }
+  std::string HintedLowercaseName = MatchedDecl->getName();
+  std::transform(HintedLowercaseName.begin(), HintedLowercaseName.end(),
+                 HintedLowercaseName.begin(), ::tolower);
+  diag(MatchedDecl->getLocation(), "Don’t use ALL_CAPS for enumerators")
+      << FixItHint::CreateInsertion(MatchedDecl->getLocation(),
+                                    HintedLowercaseName);
+}
+}
+} // namespace tidy
+} // namespace clang
Index: docs/clang-tidy/checks/cppcoreguidelines-enum-all-caps.rst
===================================================================
--- /dev/null
+++ docs/clang-tidy/checks/cppcoreguidelines-enum-all-caps.rst
@@ -0,0 +1,9 @@
+cppcoreguidelines-enum-all-caps
+=============================
+
+This check flags all ALL_CAPS enumerations.
+
+Enumerations should not be named using ALL_CAPS to avoid clashes with macros.
+
+This rule is part of the "Enumerations" profile of the C++ Core Guidelines, see
+https://github.com/isocpp/CppCoreGuidelines/blob/master/CppCoreGuidelines.md#-enum5-dont-use-all_caps-for-enumerators
Index: docs/clang-tidy/checks/list.rst
===================================================================
--- docs/clang-tidy/checks/list.rst
+++ docs/clang-tidy/checks/list.rst
@@ -6,6 +6,7 @@
    cert-static-object-exception
    cert-thrown-exception-type
    cert-variadic-function-def
+   cppcoreguidelines-enum-all-caps
    cppcoreguidelines-pro-bounds-array-to-pointer-decay
    cppcoreguidelines-pro-bounds-constant-array-index
    cppcoreguidelines-pro-bounds-pointer-arithmetic
Index: test/clang-tidy/cppcoreguidelines-enum-all-caps.cpp
===================================================================
--- /dev/null
+++ test/clang-tidy/cppcoreguidelines-enum-all-caps.cpp
@@ -0,0 +1,20 @@
+// RUN: clang-tidy -checks=cppcoreguidelines-enum-all-caps %s
+
+enum color {
+RED = 0xFF0000,
+// CHECK-MESSAGES: :[[@LINE-1]]:6: warning: Don’t use ALL_CAPS for enumerators [cppcoreguidelines-enum-all-caps]
+// CHECK-FIXES: red
+BLUE_COLOR = 0x0000FF,
+// CHECK-MESSAGES: :[[@LINE-1]]:6: warning: Don’t use ALL_CAPS for enumerators [cppcoreguidelines-enum-all-caps]
+// CHECK-FIXES: blue_color
+COOL_GREEN_123
+// CHECK-MESSAGES: :[[@LINE-1]]:6: warning: Don’t use ALL_CAPS for enumerators [cppcoreguidelines-enum-all-caps]
+// CHECK-FIXES: cool_green_123
+};
+
+// These are OK
+enum star_wars_character {
+  Chewbacca = 0,
+  Yoda = 1,
+  Darth_Vader = 2
+};