diff --git a/clang/lib/Sema/SemaDecl.cpp b/clang/lib/Sema/SemaDecl.cpp
--- a/clang/lib/Sema/SemaDecl.cpp
+++ b/clang/lib/Sema/SemaDecl.cpp
@@ -15539,6 +15539,34 @@
     // shouldn't be diagnosing.
     LookupName(Previous, S);
 
+    // Under MSVC, the 'enum' specifier can be used for typedef'd enums.
+    // Note that lookup only fails in C, not C++, so this if condition
+    // is only used for C code.
+    if (getLangOpts().MSVCCompat && (Kind == TTK_Enum) && Previous.empty() &&
+        (TUK == TUK_Reference)) {
+      LookupResult TypedefEnumLookup(*this, Name, NameLoc, LookupOrdinaryName,
+                                     Redecl);
+      LookupName(TypedefEnumLookup, S);
+
+      if (!TypedefEnumLookup.empty()) {
+        if (TypedefNameDecl *TD =
+                dyn_cast<TypedefNameDecl>(TypedefEnumLookup.getFoundDecl())) {
+          const Type *UnderlyingTypePtr =
+              TD->getUnderlyingType().getTypePtrOrNull();
+
+          if (UnderlyingTypePtr) {
+            if (EnumDecl *UnderlyingEnumDecl =
+                    dyn_cast<EnumDecl>(UnderlyingTypePtr->getAsTagDecl())) {
+              // We only allow this for anonymous enums
+              if (UnderlyingEnumDecl->getDeclName().isEmpty()) {
+                Previous.addDecl(UnderlyingEnumDecl);
+              }
+            }
+          }
+        }
+      }
+    }
+
     // When declaring or defining a tag, ignore ambiguities introduced
     // by types using'ed into this scope.
     if (Previous.isAmbiguous() &&
@@ -15721,9 +15749,12 @@
       if (TypedefNameDecl *TD = dyn_cast<TypedefNameDecl>(PrevDecl)) {
         if (const TagType *TT = TD->getUnderlyingType()->getAs<TagType>()) {
           TagDecl *Tag = TT->getDecl();
-          if (Tag->getDeclName() == Name &&
-              Tag->getDeclContext()->getRedeclContext()
-                          ->Equals(TD->getDeclContext()->getRedeclContext())) {
+          bool AnonymousEnumEligible = getLangOpts().MSVCCompat &&
+                                       (Kind == TTK_Enum) &&
+                                       Tag->getDeclName().isEmpty();
+          if ((Tag->getDeclName() == Name || AnonymousEnumEligible) &&
+              Tag->getDeclContext()->getRedeclContext()->Equals(
+                  TD->getDeclContext()->getRedeclContext())) {
             PrevDecl = Tag;
             Previous.clear();
             Previous.addDecl(Tag);
diff --git a/clang/test/Sema/enum-typedef-msvc.c b/clang/test/Sema/enum-typedef-msvc.c
new file mode 100644
--- /dev/null
+++ b/clang/test/Sema/enum-typedef-msvc.c
@@ -0,0 +1,15 @@
+// RUN: %clang_cc1 -fsyntax-only -verify %s
+// RUN: %clang_cc1 -fsyntax-only -verify -fms-compatibility -DUSE_MSVC_COMPAT %s
+
+typedef enum {
+  A
+} Foo;
+
+void func() {
+#ifdef USE_MSVC_COMPAT
+  enum Foo foo; // expected-no-diagnostics
+#else
+  enum Foo foo; // expected-error {{variable has incomplete type 'enum Foo'}} // expected-note {{forward declaration of 'enum Foo'}}
+#endif
+  (void)foo;
+}
diff --git a/clang/test/Sema/enum-typedef-msvc.cpp b/clang/test/Sema/enum-typedef-msvc.cpp
new file mode 100644
--- /dev/null
+++ b/clang/test/Sema/enum-typedef-msvc.cpp
@@ -0,0 +1,16 @@
+// RUN: %clang_cc1 -fsyntax-only -verify -fms-compatibility %s
+
+typedef enum {
+  First,
+  Second
+} MyEnum;
+
+class AMyInterface {
+  virtual void MyFunc(enum MyEnum *param) = 0;
+};
+
+class MyImpl : public AMyInterface {
+  virtual void MyFunc(enum MyEnum *param) override {}
+};
+
+// expected-no-diagnostics