Index: clang/include/clang/AST/Decl.h
===================================================================
--- clang/include/clang/AST/Decl.h
+++ clang/include/clang/AST/Decl.h
@@ -907,6 +907,10 @@
     /// declared.
     unsigned ScopeDepthOrObjCQuals : 7;
 
+    /// If this ParmVarDecl is a parameter of a deduction guide. This ensures
+    /// that we don't profile it the same as the parameter of the constructor.
+    unsigned IsParamOfDeductionGuide : 1;
+
     /// The number of parameters preceding this parameter in the
     /// function parameter scope in which it was declared.
     unsigned ParameterIndex : NumParameterIndexBits;
@@ -1544,6 +1548,7 @@
     assert(ParmVarDeclBits.DefaultArgKind == DAK_None);
     assert(ParmVarDeclBits.IsKNRPromoted == false);
     assert(ParmVarDeclBits.IsObjCMethodParam == false);
+    assert(ParmVarDeclBits.IsParamOfDeductionGuide == false);
     setDefaultArg(DefArg);
   }
 
@@ -1611,6 +1616,13 @@
     ParmVarDeclBits.IsKNRPromoted = promoted;
   }
 
+  void setIsParamOfDeductionGuide(bool Value = true) {
+    ParmVarDeclBits.IsParamOfDeductionGuide = Value;
+  }
+  bool isParamOfDeductionGuide() const {
+    return ParmVarDeclBits.IsParamOfDeductionGuide;
+  }
+
   Expr *getDefaultArg();
   const Expr *getDefaultArg() const {
     return const_cast<ParmVarDecl *>(this)->getDefaultArg();
Index: clang/lib/AST/StmtProfile.cpp
===================================================================
--- clang/lib/AST/StmtProfile.cpp
+++ clang/lib/AST/StmtProfile.cpp
@@ -110,6 +110,7 @@
           VisitType(Parm->getType());
           ID.AddInteger(Parm->getFunctionScopeDepth());
           ID.AddInteger(Parm->getFunctionScopeIndex());
+          ID.AddBoolean(Parm->isParamOfDeductionGuide());
           return;
         }
 
Index: clang/lib/Sema/SemaTemplate.cpp
===================================================================
--- clang/lib/Sema/SemaTemplate.cpp
+++ clang/lib/Sema/SemaTemplate.cpp
@@ -1880,9 +1880,7 @@
                              MultiLevelTemplateArgumentList &Args) {
     TypeSourceInfo *OldDI = OldParam->getTypeSourceInfo();
     TypeSourceInfo *NewDI;
-    if (!Args.getNumLevels())
-      NewDI = OldDI;
-    else if (auto PackTL = OldDI->getTypeLoc().getAs<PackExpansionTypeLoc>()) {
+    if (auto PackTL = OldDI->getTypeLoc().getAs<PackExpansionTypeLoc>()) {
       // Expand out the one and only element in each inner pack.
       Sema::ArgumentPackSubstitutionIndexRAII SubstIndex(SemaRef, 0);
       NewDI =
@@ -1912,9 +1910,7 @@
     // constructor.
     ExprResult NewDefArg;
     if (OldParam->hasDefaultArg()) {
-      NewDefArg = Args.getNumLevels()
-                      ? SemaRef.SubstExpr(OldParam->getDefaultArg(), Args)
-                      : OldParam->getDefaultArg();
+      NewDefArg = SemaRef.SubstExpr(OldParam->getDefaultArg(), Args);
       if (NewDefArg.isInvalid())
         return nullptr;
     }
@@ -1929,6 +1925,8 @@
                                                 NewDefArg.get());
     NewParam->setScopeInfo(OldParam->getFunctionScopeDepth(),
                            OldParam->getFunctionScopeIndex());
+    NewParam->setIsParamOfDeductionGuide();
+    SemaRef.CurrentInstantiationScope->InstantiatedLocal(OldParam, NewParam);
     return NewParam;
   }
 
Index: clang/test/SemaCXX/cxx1z-class-template-argument-deduction.cpp
===================================================================
--- clang/test/SemaCXX/cxx1z-class-template-argument-deduction.cpp
+++ clang/test/SemaCXX/cxx1z-class-template-argument-deduction.cpp
@@ -348,6 +348,22 @@
   };
 }
 
+namespace rdar41330135 {
+template <int> struct A {};
+template <class T>
+struct S {
+  template <class U>
+  S(T a, U t, A<sizeof(t)>);
+};
+template <class T> struct D {
+  D(T t, A<sizeof(t)>);
+};
+int f() {
+  S s(0, 0, A<sizeof(int)>());
+  D d(0, A<sizeof(int)>());
+}
+}
+
 #else
 
 // expected-no-diagnostics