diff --git a/clang/include/clang/AST/ASTStructuralEquivalence.h b/clang/include/clang/AST/ASTStructuralEquivalence.h
--- a/clang/include/clang/AST/ASTStructuralEquivalence.h
+++ b/clang/include/clang/AST/ASTStructuralEquivalence.h
@@ -69,15 +69,19 @@
   /// \c true if the last diagnostic came from ToCtx.
   bool LastDiagFromC2 = false;
 
+  /// Whether to ignore comparing the depth of NonTypeParmDecl
+  bool IgnoreDepth;
+
   StructuralEquivalenceContext(
       ASTContext &FromCtx, ASTContext &ToCtx,
       llvm::DenseSet<std::pair<Decl *, Decl *>> &NonEquivalentDecls,
-      StructuralEquivalenceKind EqKind,
-      bool StrictTypeSpelling = false, bool Complain = true,
-      bool ErrorOnTagTypeMismatch = false)
+      StructuralEquivalenceKind EqKind, bool StrictTypeSpelling = false,
+      bool Complain = true, bool ErrorOnTagTypeMismatch = false,
+      bool IgnoreDepth = false)
       : FromCtx(FromCtx), ToCtx(ToCtx), NonEquivalentDecls(NonEquivalentDecls),
         EqKind(EqKind), StrictTypeSpelling(StrictTypeSpelling),
-        ErrorOnTagTypeMismatch(ErrorOnTagTypeMismatch), Complain(Complain) {}
+        ErrorOnTagTypeMismatch(ErrorOnTagTypeMismatch), Complain(Complain),
+        IgnoreDepth(IgnoreDepth) {}
 
   DiagnosticBuilder Diag1(SourceLocation Loc, unsigned DiagID);
   DiagnosticBuilder Diag2(SourceLocation Loc, unsigned DiagID);
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
@@ -34,6 +34,7 @@
 #include "clang/AST/LambdaCapture.h"
 #include "clang/AST/NestedNameSpecifier.h"
 #include "clang/AST/OperationKinds.h"
+#include "clang/AST/ParentMapContext.h"
 #include "clang/AST/Stmt.h"
 #include "clang/AST/StmtCXX.h"
 #include "clang/AST/StmtObjC.h"
@@ -506,7 +507,8 @@
     template <typename T>
     bool hasSameVisibilityContextAndLinkage(T *Found, T *From);
 
-    bool IsStructuralMatch(Decl *From, Decl *To, bool Complain = true);
+    bool IsStructuralMatch(Decl *From, Decl *To, bool Complain = true,
+                           bool IgnoreDepth = true);
     ExpectedDecl VisitDecl(Decl *D);
     ExpectedDecl VisitImportDecl(ImportDecl *D);
     ExpectedDecl VisitEmptyDecl(EmptyDecl *D);
@@ -2243,7 +2245,8 @@
                                     : StructuralEquivalenceKind::Default;
 }
 
-bool ASTNodeImporter::IsStructuralMatch(Decl *From, Decl *To, bool Complain) {
+bool ASTNodeImporter::IsStructuralMatch(Decl *From, Decl *To, bool Complain,
+                                        bool IgnoreDepth) {
   // Eliminate a potential failure point where we attempt to re-import
   // something we're trying to import while completing ToRecord.
   Decl *ToOrigin = Importer.GetOriginalDecl(To);
@@ -2254,7 +2257,7 @@
   StructuralEquivalenceContext Ctx(
       Importer.getFromContext(), Importer.getToContext(),
       Importer.getNonEquivalentDecls(), getStructuralEquivalenceKind(Importer),
-      false, Complain);
+      false, Complain, false, IgnoreDepth);
   return Ctx.IsEquivalent(From, To);
 }
 
@@ -5822,7 +5825,11 @@
         if (!hasSameVisibilityContextAndLinkage(FoundTemplate, D))
           continue;
 
-        if (IsStructuralMatch(D, FoundTemplate)) {
+        // FIXME: sufficient conditon for 'IgnoreDepth'?
+        bool IgnoreDepth =
+            FoundTemplate->getFriendObjectKind() != Decl::FOK_None &&
+            !D->specializations().empty();
+        if (IsStructuralMatch(D, FoundTemplate, true, IgnoreDepth)) {
           ClassTemplateDecl *TemplateWithDef =
               getTemplateDefinition(FoundTemplate);
           if (D->isThisDeclarationADefinition() && TemplateWithDef)
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
@@ -1092,7 +1092,7 @@
   case Type::TemplateTypeParm: {
     const auto *Parm1 = cast<TemplateTypeParmType>(T1);
     const auto *Parm2 = cast<TemplateTypeParmType>(T2);
-    if (Parm1->getDepth() != Parm2->getDepth())
+    if (!Context.IgnoreDepth && Parm1->getDepth() != Parm2->getDepth())
       return false;
     if (Parm1->getIndex() != Parm2->getIndex())
       return false;
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
@@ -4212,6 +4212,56 @@
   EXPECT_TRUE(Imported->getPreviousDecl());
 }
 
+TEST_P(ImportFriendClasses, SkipComparingFriendTemplateDepth) {
+  Decl *ToTU = getToTuDecl(
+      R"(
+      template <class T, T U>
+      class A;
+
+      template <class T, T U>
+      class A {
+      public:
+        template <class P, P Q>
+        friend class A;
+
+        A(T x)  :x(x) {}
+
+      private:
+        T x;
+      };
+      )",
+      Lang_CXX11);
+
+  auto *Fwd = FirstDeclMatcher<ClassTemplateDecl>().match(
+      ToTU, classTemplateDecl(hasName("A")));
+  Decl *FromTU = getTuDecl(
+      R"(
+      template <class T, T U>
+      class A;
+
+      template <class T, T U>
+      class A {
+      public:
+        template <class P, P Q>
+        friend class A;
+
+        A(T x) : x(x) {}
+
+      private:
+        T x;
+      };
+
+      A<int,3> a1(0);
+      )",
+      Lang_CXX11, "input1.cc");
+  auto *FromA = FirstDeclMatcher<ClassTemplateDecl>().match(
+      FromTU, classTemplateDecl(hasName("A")));
+  auto *ToA = Import(FromA, Lang_CXX11);
+  EXPECT_TRUE(ToA);
+  EXPECT_EQ(Fwd->getTemplatedDecl()->getTypeForDecl(),
+            ToA->getTemplatedDecl()->getTypeForDecl());
+}
+
 TEST_P(ImportFriendClasses,
        ImportOfClassTemplateDefinitionShouldConnectToFwdFriend) {
   Decl *ToTU = getToTuDecl(