diff --git a/clang/lib/AST/ASTStructuralEquivalence.cpp b/clang/lib/AST/ASTStructuralEquivalence.cpp
--- a/clang/lib/AST/ASTStructuralEquivalence.cpp
+++ b/clang/lib/AST/ASTStructuralEquivalence.cpp
@@ -2057,8 +2057,13 @@
   if (!IsStructurallyEquivalent(D1->getIdentifier(), D2->getIdentifier()))
     return false;
 
-  if (!IsStructurallyEquivalent(D1->getClassInterface()->getIdentifier(),
-                                D2->getClassInterface()->getIdentifier()))
+  const ObjCInterfaceDecl *Intf1 = D1->getClassInterface(),
+                          *Intf2 = D2->getClassInterface();
+  if ((!Intf1 || !Intf2) && (Intf1 != Intf2))
+    return false;
+
+  if (Intf1 &&
+      !IsStructurallyEquivalent(Intf1->getIdentifier(), Intf2->getIdentifier()))
     return false;
 
   // Compare protocols.
@@ -2077,7 +2082,8 @@
     return false;
 
   // Compare ivars.
-  QualType D2Type = Context.ToCtx.getObjCInterfaceType(D2->getClassInterface());
+  QualType D2Type =
+      Intf2 ? Context.ToCtx.getObjCInterfaceType(Intf2) : QualType();
   ObjCCategoryDecl::ivar_iterator Ivar2 = D2->ivar_begin(),
                                   Ivar2End = D2->ivar_end();
   for (ObjCCategoryDecl::ivar_iterator Ivar1 = D1->ivar_begin(),
diff --git a/clang/unittests/AST/StructuralEquivalenceTest.cpp b/clang/unittests/AST/StructuralEquivalenceTest.cpp
--- a/clang/unittests/AST/StructuralEquivalenceTest.cpp
+++ b/clang/unittests/AST/StructuralEquivalenceTest.cpp
@@ -1143,6 +1143,18 @@
   EXPECT_FALSE(testStructuralMatch(t));
 }
 
+TEST_F(StructuralEquivalenceObjCCategoryTest, CategoriesWithoutInterfaces) {
+  auto t = makeDecls<ObjCCategoryDecl>("                  @interface A(X) @end",
+                                       "@interface A @end @interface A(X) @end",
+                                       Lang_OBJC, objcCategoryDecl());
+  EXPECT_FALSE(testStructuralMatch(t));
+
+  auto t2 = makeDecls<ObjCCategoryDecl>("@interface A(X) @end",
+                                        "@interface A(X) @end",
+                                        Lang_OBJC, objcCategoryDecl());
+  EXPECT_TRUE(testStructuralMatch(t2));
+}
+
 TEST_F(StructuralEquivalenceObjCCategoryTest, CategoryAndExtension) {
   auto t = makeDecls<ObjCCategoryDecl>("@interface A @end @interface A(X) @end",
                                        "@interface A @end @interface A() @end",