Index: lib/CodeGen/CGDebugInfo.cpp
===================================================================
--- lib/CodeGen/CGDebugInfo.cpp
+++ lib/CodeGen/CGDebugInfo.cpp
@@ -2475,8 +2475,9 @@
     case Type::SubstTemplateTypeParm:
       T = cast<SubstTemplateTypeParmType>(T)->getReplacementType();
       break;
-    case Type::Auto: {
-      QualType DT = cast<AutoType>(T)->getDeducedType();
+    case Type::Auto:
+    case Type::DeducedTemplateSpecialization: {
+      QualType DT = cast<DeducedType>(T)->getDeducedType();
       assert(!DT.isNull() && "Undeduced types shouldn't reach here.");
       T = DT;
       break;
Index: test/CodeGenCXX/debug-info-template-deduction-guide.cpp
===================================================================
--- /dev/null
+++ test/CodeGenCXX/debug-info-template-deduction-guide.cpp
@@ -0,0 +1,17 @@
+// RUN: %clang -S -emit-llvm -target x86_64-unknown_unknown -g %s -o - -std=c++1z | FileCheck %s
+
+// Verify that we don't crash when emitting debug information for objects
+// created from a deduced template specialization.
+
+template <class T>
+struct S {
+  S(T) {}
+};
+
+// CHECK: !DIGlobalVariable(name: "s1"
+// CHECK-SAME: type: [[TYPE_NUM:![0-9]+]]
+// CHECK: !DIGlobalVariable(name: "s2"
+// CHECK-SAME: type: [[TYPE_NUM]]
+// CHECK: [[TYPE_NUM]] = distinct !DICompositeType(tag: DW_TAG_structure_type, name: "S<int>",
+S s1(42);
+S<int> s2(42);