Index: lib/AST/ASTImporter.cpp
===================================================================
--- lib/AST/ASTImporter.cpp
+++ lib/AST/ASTImporter.cpp
@@ -1631,7 +1631,12 @@
   // We may already have a record of the same name; try to find and match it.
   RecordDecl *AdoptDecl = nullptr;
   RecordDecl *PrevDecl = nullptr;
-  if (!DC->isFunctionOrMethod()) {
+
+  // There are unnamed structures that are not anonymous.
+  // They cause wrong conflict detections due to the null string name.
+  bool isNotAnonymousButUnnamed = (!D->isAnonymousStructOrUnion() && SearchName.getAsString() == "");
+
+  if (!DC->isFunctionOrMethod() && !isNotAnonymousButUnnamed) {
     SmallVector<NamedDecl *, 4> ConflictingDecls;
     SmallVector<NamedDecl *, 2> FoundDecls;
     DC->getRedeclContext()->localUncachedLookup(SearchName, FoundDecls);
Index: unittests/AST/ASTImporterTest.cpp
===================================================================
--- unittests/AST/ASTImporterTest.cpp
+++ unittests/AST/ASTImporterTest.cpp
@@ -485,6 +485,65 @@
                                        has(atomicType()))))))))));
 }
 
+TEST(ImportDecl, ImportUnnamedRecordDecl) {
+  MatchVerifier<Decl> Verifier;
+  EXPECT_TRUE(
+        testImport(
+          "void declToImport() {"
+          "  struct Root {"
+          "    struct { int a; } A;"
+          "    struct { float b; } B;"
+          "  } root;"
+          "}",
+          Lang_C, "", Lang_C, Verifier,
+          functionDecl(
+            hasBody(
+              compoundStmt(
+                has(
+                  declStmt(
+                    has(
+                      recordDecl(
+                        has(
+                          recordDecl(
+                            has(
+                              fieldDecl(
+                                hasType(asString("int")))))),
+                        has(
+                          recordDecl(
+                            has(
+                              fieldDecl(
+                                hasType(asString("float"))))))
+                        )))))))));
+}
+
+TEST(ImportDecl, ImportAnonymousRecordDecl) {
+  MatchVerifier<Decl> Verifier;
+  EXPECT_TRUE(
+        testImport(
+          "void declToImport() {"
+          "  struct Root {"
+          "    union { char a;};"
+          "    union { int b;};"
+          "  } root;"
+          "}",
+          Lang_C, "", Lang_C, Verifier,
+          functionDecl(
+            hasBody(
+              compoundStmt(
+                has(
+                  declStmt(
+                    has(
+                      recordDecl(
+                        has(
+                          recordDecl(
+                            has(
+                              fieldDecl(hasType(asString("char")))))),
+                        has(
+                          recordDecl(
+                            has(
+                              fieldDecl(hasType(asString("int"))))))
+                        )))))))));
+}
 
 } // end namespace ast_matchers
 } // end namespace clang