diff --git a/include/llvm/Target/Target.td b/include/llvm/Target/Target.td
index 87bd84ec84b..42747af41e4 100644
--- a/include/llvm/Target/Target.td
+++ b/include/llvm/Target/Target.td
@@ -495,7 +495,8 @@ def ptr_rc : PointerLikeRegClass<0>;
 
 /// unknown definition - Mark this operand as being of unknown type, causing
 /// it to be resolved by inference in the context it is used.
-def unknown;
+class unknown_class;
+def unknown : unknown_class;
 
 /// AsmOperandClass - Representation for the kinds of operands which the target
 /// specific parser can create and the assembly matcher may need to distinguish.
diff --git a/utils/TableGen/CodeGenDAGPatterns.cpp b/utils/TableGen/CodeGenDAGPatterns.cpp
index 8713a569162..0dcb4eed4e5 100644
--- a/utils/TableGen/CodeGenDAGPatterns.cpp
+++ b/utils/TableGen/CodeGenDAGPatterns.cpp
@@ -1535,7 +1535,7 @@ bool TreePatternNode::ApplyTypeConstraints(TreePattern &TP, bool NotRegisters) {
         const CodeGenRegisterClass &RC =
           CDP.getTargetInfo().getRegisterClass(RegClass);
         MadeChange |= UpdateNodeType(ResNo, RC.getValueTypes(), TP);
-      } else if (ResultNode->getName() == "unknown") {
+      } else if (ResultNode->isSubClassOf("unknown_class")) {
         // Nothing to do.
       } else {
         assert(ResultNode->isSubClassOf("RegisterClass") &&
@@ -1602,7 +1602,7 @@ bool TreePatternNode::ApplyTypeConstraints(TreePattern &TP, bool NotRegisters) {
         MadeChange |= Child->UpdateNodeType(ChildResNo, VT, TP);
       } else if (OperandNode->isSubClassOf("PointerLikeRegClass")) {
         MadeChange |= Child->UpdateNodeType(ChildResNo, MVT::iPTR, TP);
-      } else if (OperandNode->getName() == "unknown") {
+      } else if (OperandNode->isSubClassOf("unknown_class")) {
         // Nothing to do.
       } else
         llvm_unreachable("Unknown operand type!");
diff --git a/utils/TableGen/CodeGenInstruction.cpp b/utils/TableGen/CodeGenInstruction.cpp
index 38e2b832f2f..836279b89ab 100644
--- a/utils/TableGen/CodeGenInstruction.cpp
+++ b/utils/TableGen/CodeGenInstruction.cpp
@@ -101,7 +101,7 @@ CGIOperandList::CGIOperandList(Record *R) : TheDef(R) {
     } else if (Rec->isSubClassOf("RegisterClass")) {
       OperandType = "OPERAND_REGISTER";
     } else if (!Rec->isSubClassOf("PointerLikeRegClass") &&
-               Rec->getName() != "unknown")
+               !Rec->isSubClassOf("unknown_class"))
       throw "Unknown operand class '" + Rec->getName() +
       "' in '" + R->getName() + "' instruction!";