--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/llvm/test/TableGen/subst.td	Thu Feb 13 15:10:13 2020 +0900
@@ -0,0 +1,67 @@
+// RUN: llvm-tblgen %s | FileCheck %s
+// XFAIL: vg_leak
+
+class Honorific<string t> {
+  string honorific = t;
+}
+
+def Mr : Honorific<"Mr.">;
+def Ms : Honorific<"Ms.">;
+def Mrs : Honorific<"Mrs.">;
+def TVAR : Honorific<"Bogus">;
+
+class Name<string n, Honorific t> {
+  string name = n;
+  Honorific honorific = t;
+}
+
+class AName<string name, Honorific honorific> : 
+  Name<!subst("FIRST", "John", !subst("LAST", "Smith", name)),
+       !subst(TVAR, Mr, honorific)>;
+
+def JohnSmith : AName<"FIRST LAST", TVAR>;
+def JaneSmith : AName<"Jane LAST", Ms>;
+def JohnSmithJones : AName<"FIRST LAST-Jones", Mr>;
+def JimmyJohnson : AName<"Jimmy Johnson", Mr>;
+
+// CHECK:      ------------- Classes -----------------
+// CHECK-NEXT: class AName<string AName:name = ?, Honorific AName:honorific = ?> {
+// CHECK-NEXT:   string name = !subst("FIRST", "John", !subst("LAST", "Smith", AName:name));
+// CHECK-NEXT:   Honorific honorific = !subst(TVAR, Mr, AName:honorific);
+// CHECK-NEXT: }
+// CHECK-NEXT: class Honorific<string Honorific:t = ?> {
+// CHECK-NEXT:   string honorific = Honorific:t;
+// CHECK-NEXT: }
+// CHECK-NEXT: class Name<string Name:n = ?, Honorific Name:t = ?> {
+// CHECK-NEXT:   string name = Name:n;
+// CHECK-NEXT:   Honorific honorific = Name:t;
+// CHECK-NEXT: }
+// CHECK-NEXT: ------------- Defs -----------------
+// CHECK-NEXT: def JaneSmith {
+// CHECK-NEXT:   string name = "Jane Smith";
+// CHECK-NEXT:   Honorific honorific = Ms;
+// CHECK-NEXT: }
+// CHECK-NEXT: def JimmyJohnson {
+// CHECK-NEXT:   string name = "Jimmy Johnson";
+// CHECK-NEXT:   Honorific honorific = Mr;
+// CHECK-NEXT: }
+// CHECK-NEXT: def JohnSmith {
+// CHECK-NEXT:   string name = "John Smith";
+// CHECK-NEXT:   Honorific honorific = Mr;
+// CHECK-NEXT: }
+// CHECK-NEXT: def JohnSmithJones {
+// CHECK-NEXT:   string name = "John Smith-Jones";
+// CHECK-NEXT:   Honorific honorific = Mr;
+// CHECK-NEXT: }
+// CHECK-NEXT: def Mr 
+// CHECK-NEXT:   string honorific = "Mr.";
+// CHECK-NEXT: }
+// CHECK-NEXT: def Mrs {
+// CHECK-NEXT:   string honorific = "Mrs.";
+// CHECK-NEXT: }
+// CHECK-NEXT: def Ms {
+// CHECK-NEXT:   string honorific = "Ms.";
+// CHECK-NEXT: }
+// CHECK-NEXT: def TVAR {
+// CHECK-NEXT:   string honorific = "Bogus";
+// CHECK-NEXT: }