diff --git a/clang-tools-extra/clangd/unittests/SemanticHighlightingTests.cpp b/clang-tools-extra/clangd/unittests/SemanticHighlightingTests.cpp
--- a/clang-tools-extra/clangd/unittests/SemanticHighlightingTests.cpp
+++ b/clang-tools-extra/clangd/unittests/SemanticHighlightingTests.cpp
@@ -780,6 +780,16 @@
             $LocalVariable_decl[[d]]($LocalVariable[[b]]) ]() {}();
         }
       )cpp",
+      // Enum base specifier
+      R"cpp(
+        using $Primitive_decl[[MyTypedef]] = int;
+        enum $Enum_decl[[MyEnum]] : $Primitive[[MyTypedef]] {};
+      )cpp",
+      // Enum base specifier
+      R"cpp(
+        typedef int $Primitive_decl[[MyTypedef]];
+        enum $Enum_decl[[MyEnum]] : $Primitive[[MyTypedef]] {};
+      )cpp",
   };
   for (const auto &TestCase : TestCases)
     // Mask off scope modifiers to keep the tests manageable.
diff --git a/clang-tools-extra/clangd/unittests/XRefsTests.cpp b/clang-tools-extra/clangd/unittests/XRefsTests.cpp
--- a/clang-tools-extra/clangd/unittests/XRefsTests.cpp
+++ b/clang-tools-extra/clangd/unittests/XRefsTests.cpp
@@ -880,6 +880,15 @@
         };
       )cpp",
 
+      R"cpp(// Enum base
+        typedef int $decl[[MyTypeDef]];
+        enum Foo : My^TypeDef {};
+      )cpp",
+      R"cpp(// Enum base
+        using $decl[[MyTypeDef]] = int;
+        enum Foo : My^TypeDef {};
+      )cpp",
+
       R"objc(
         @protocol Dog;
         @protocol $decl[[Dog]]
@@ -1953,6 +1962,16 @@
           [[f^oo]](s);
         }
       )cpp",
+
+      // Enum base
+      R"cpp(
+        typedef int $def[[MyTypeDef]];
+        enum MyEnum : [[MyTy^peDef]] { };
+      )cpp",
+      R"cpp(
+        using $def[[MyTypeDef]] = int;
+        enum MyEnum : [[MyTy^peDef]] { };
+      )cpp",
   };
   for (const char *Test : Tests)
     checkFindRefs(Test);
diff --git a/clang/include/clang/AST/RecursiveASTVisitor.h b/clang/include/clang/AST/RecursiveASTVisitor.h
--- a/clang/include/clang/AST/RecursiveASTVisitor.h
+++ b/clang/include/clang/AST/RecursiveASTVisitor.h
@@ -1863,6 +1863,9 @@
 DEF_TRAVERSE_DECL(EnumDecl, {
   TRY_TO(TraverseDeclTemplateParameterLists(D));
 
+  if (auto *TSI = D->getIntegerTypeSourceInfo())
+    TRY_TO(TraverseTypeLoc(TSI->getTypeLoc()));
+
   if (D->getTypeForDecl())
     TRY_TO(TraverseType(QualType(D->getTypeForDecl(), 0)));
 
diff --git a/clang/lib/Index/IndexTypeSourceInfo.cpp b/clang/lib/Index/IndexTypeSourceInfo.cpp
--- a/clang/lib/Index/IndexTypeSourceInfo.cpp
+++ b/clang/lib/Index/IndexTypeSourceInfo.cpp
@@ -7,8 +7,10 @@
 //===----------------------------------------------------------------------===//
 
 #include "IndexingContext.h"
+#include "clang/AST/Decl.h"
 #include "clang/AST/RecursiveASTVisitor.h"
 #include "llvm/ADT/ScopeExit.h"
+#include "llvm/Support/Casting.h"
 
 using namespace clang;
 using namespace index;
@@ -305,6 +307,9 @@
         for (const auto &I : CXXRD->bases()) {
           indexTypeSourceInfo(I.getTypeSourceInfo(), CXXRD, CXXRD, /*isBase=*/true);
         }
+      } else if (auto *ED = dyn_cast<EnumDecl>(D)) {
+        if (auto *TSI = ED->getIntegerTypeSourceInfo())
+          indexTypeSourceInfo(TSI, ED, ED, /*isBase=*/true);
       }
       indexDeclContext(D);
     }
diff --git a/clang/unittests/Index/IndexTests.cpp b/clang/unittests/Index/IndexTests.cpp
--- a/clang/unittests/Index/IndexTests.cpp
+++ b/clang/unittests/Index/IndexTests.cpp
@@ -377,6 +377,18 @@
                              Not(HasRole(SymbolRole::RelationBaseOf)))));
 }
 
+TEST(IndexTest, EnumBase) {
+  std::string Code = R"cpp(
+    typedef int MyTypedef;
+    enum Foo : MyTypedef {};
+  )cpp";
+  auto Index = std::make_shared<Indexer>();
+  tooling::runToolOnCode(std::make_unique<IndexAction>(Index), Code);
+  // A should not be the base of anything.
+  EXPECT_THAT(Index->Symbols,
+              Contains(AllOf(QName("MyTypedef"), HasRole(SymbolRole::Reference),
+                             WrittenAt(Position(3, 16)))));
+}
 } // namespace
 } // namespace index
 } // namespace clang