diff --git a/clang/lib/AST/ASTImporter.cpp b/clang/lib/AST/ASTImporter.cpp
--- a/clang/lib/AST/ASTImporter.cpp
+++ b/clang/lib/AST/ASTImporter.cpp
@@ -2256,7 +2256,8 @@
           if (!FromUT->isIncompleteType() && !FoundUT->isIncompleteType())
             return Importer.MapImported(D, FoundTypedef);
         }
-        // FIXME Handle redecl chain.
+        // FIXME Handle redecl chain. When you do that make consistent changes
+        // in ASTImporterLookupTable too.
         break;
       }
 
diff --git a/clang/lib/AST/ASTImporterLookupTable.cpp b/clang/lib/AST/ASTImporterLookupTable.cpp
--- a/clang/lib/AST/ASTImporterLookupTable.cpp
+++ b/clang/lib/AST/ASTImporterLookupTable.cpp
@@ -26,17 +26,30 @@
     LT.add(D);
     return true;
   }
+  // In most cases the FriendDecl contains the declaration of the befriended
+  // class as a child node, so it is discovered during the recursive
+  // visitation. However, there are cases when the befriended class is not a
+  // child, thus it must be fetched explicitly from the FriendDecl, and only
+  // then can we add it to the lookup table.
   bool VisitFriendDecl(FriendDecl *D) {
     if (D->getFriendType()) {
       QualType Ty = D->getFriendType()->getType();
-      // FIXME Can this be other than elaborated?
-      QualType NamedTy = cast<ElaboratedType>(Ty)->getNamedType();
-      if (!NamedTy->isDependentType()) {
-        if (const auto *RTy = dyn_cast<RecordType>(NamedTy))
+      if (isa<ElaboratedType>(Ty))
+        Ty = cast<ElaboratedType>(Ty)->getNamedType();
+      // A FriendDecl with a dependent type (e.g. ClassTemplateSpecialization)
+      // always has that decl as child node.
+      // However, there are non-dependent cases which does not have the
+      // type as a child node. We have to dig up that type now.
+      if (!Ty->isDependentType()) {
+        if (const auto *RTy = dyn_cast<RecordType>(Ty))
           LT.add(RTy->getAsCXXRecordDecl());
-        else if (const auto *SpecTy =
-                     dyn_cast<TemplateSpecializationType>(NamedTy)) {
+        else if (const auto *SpecTy = dyn_cast<TemplateSpecializationType>(Ty))
           LT.add(SpecTy->getAsCXXRecordDecl());
+        else if (isa<TypedefType>(Ty)) {
+          // We do not put friend typedefs to the lookup table because
+          // ASTImporter does not organize typedefs into redecl chains.
+        } else {
+          llvm_unreachable("Unhandled type of friend class");
         }
       }
     }
diff --git a/clang/unittests/AST/ASTImporterTest.cpp b/clang/unittests/AST/ASTImporterTest.cpp
--- a/clang/unittests/AST/ASTImporterTest.cpp
+++ b/clang/unittests/AST/ASTImporterTest.cpp
@@ -4246,13 +4246,27 @@
   ASSERT_EQ(Res.size(), 0u);
 }
 
+static QualType getUnderlyingType(const TypedefType *TDT) {
+  QualType T = TDT->getDecl()->getUnderlyingType();
+
+  if (const auto *Inner = dyn_cast<TypedefType>(T.getTypePtr()))
+    return getUnderlyingType(Inner);
+
+  return T;
+}
+
 static const RecordDecl * getRecordDeclOfFriend(FriendDecl *FD) {
   QualType Ty = FD->getFriendType()->getType();
-  QualType NamedTy = cast<ElaboratedType>(Ty)->getNamedType();
-  return cast<RecordType>(NamedTy)->getDecl();
+  if (auto *Inner = dyn_cast<TypedefType>(Ty.getTypePtr())) {
+    Ty = getUnderlyingType(Inner);
+  }
+  if (isa<ElaboratedType>(Ty))
+    Ty = cast<ElaboratedType>(Ty)->getNamedType();
+  return cast<RecordType>(Ty)->getDecl();
 }
 
-TEST_P(ASTImporterLookupTableTest, LookupFindsFwdFriendClassDecl) {
+TEST_P(ASTImporterLookupTableTest,
+       LookupFindsFwdFriendClassDeclWithElaboratedType) {
   TranslationUnitDecl *ToTU = getToTuDecl(
       R"(
       class Y { friend class F; };
@@ -4276,6 +4290,52 @@
   EXPECT_EQ(Res.size(), 0u);
 }
 
+TEST_P(ASTImporterLookupTableTest,
+       LookupFindsFwdFriendClassDeclWithUnelaboratedType) {
+  TranslationUnitDecl *ToTU = getToTuDecl(
+      R"(
+      class F;
+      class Y { friend F; };
+      )",
+      Lang_CXX11);
+
+  // In this case, the CXXRecordDecl is hidden, the FriendDecl is not a parent.
+  // So we must dig up the underlying CXXRecordDecl.
+  ASTImporterLookupTable LT(*ToTU);
+  auto *FriendD = FirstDeclMatcher<FriendDecl>().match(ToTU, friendDecl());
+  const RecordDecl *RD = getRecordDeclOfFriend(FriendD);
+  auto *Y = FirstDeclMatcher<CXXRecordDecl>().match(ToTU, cxxRecordDecl(hasName("Y")));
+
+  DeclarationName Name = RD->getDeclName();
+  auto Res = LT.lookup(ToTU, Name);
+  EXPECT_EQ(Res.size(), 1u);
+  EXPECT_EQ(*Res.begin(), RD);
+
+  Res = LT.lookup(Y, Name);
+  EXPECT_EQ(Res.size(), 0u);
+}
+
+TEST_P(ASTImporterLookupTableTest,
+       LookupFindsFriendClassDeclWithTypeAliasDoesNotAssert) {
+  TranslationUnitDecl *ToTU = getToTuDecl(
+      R"(
+      class F;
+      using alias_of_f = F;
+      class Y { friend alias_of_f; };
+      )",
+      Lang_CXX11);
+
+  // ASTImporterLookupTable constructor handles using declarations correctly,
+  // no assert is expected.
+  ASTImporterLookupTable LT(*ToTU);
+
+  auto *Alias = FirstDeclMatcher<TypeAliasDecl>().match(
+      ToTU, typeAliasDecl(hasName("alias_of_f")));
+  DeclarationName Name = Alias->getDeclName();
+  auto Res = LT.lookup(ToTU, Name);
+  EXPECT_EQ(Res.count(Alias), 1u);
+}
+
 TEST_P(ASTImporterLookupTableTest, LookupFindsFwdFriendClassTemplateDecl) {
   TranslationUnitDecl *ToTU = getToTuDecl(
       R"(