Index: clang/include/clang/AST/Type.h
===================================================================
--- clang/include/clang/AST/Type.h
+++ clang/include/clang/AST/Type.h
@@ -6456,8 +6456,15 @@
 }
 
 inline bool Type::isUndeducedType() const {
-  auto *DT = getContainedDeducedType();
-  return DT && !DT->isDeduced();
+  QualType Ty(this, 0);
+  while (auto *DT = Ty->getContainedDeducedType()) {
+    if (!DT->isDeduced())
+      return true;
+    Ty = DT->getDeducedType();
+    if (Ty.isNull())
+      return false;
+  }
+  return false;
 }
 
 /// Determines whether this is a type for which one can define
Index: clang/test/SemaTemplate/temp_arg_nontype_cxx1z.cpp
===================================================================
--- clang/test/SemaTemplate/temp_arg_nontype_cxx1z.cpp
+++ clang/test/SemaTemplate/temp_arg_nontype_cxx1z.cpp
@@ -335,3 +335,13 @@
   void g(int, int);
   using Int = A<int>::B<&g>::param2;
 }
+
+namespace rdar41852459 {
+template <auto V> struct G {};
+
+template <class T> struct S {
+  template <auto V> void f() {
+    G<V> x;
+  }
+};
+}