Index: include/llvm/Target/TargetRegisterInfo.h
===================================================================
--- include/llvm/Target/TargetRegisterInfo.h
+++ include/llvm/Target/TargetRegisterInfo.h
@@ -863,6 +863,17 @@
                                    int SPAdj, unsigned FIOperandNum,
                                    RegScavenger *RS = nullptr) const = 0;
 
+  /// Return the assembly name for \p Reg.
+  virtual std::string getRegAsmName(unsigned Reg) const {
+    // FIXME: We are assuming that the assembly name is equal to the TableGen
+    // name converted to lower case
+    //
+    // The TableGen name is the name of the definition for this register in the
+    // target's tablegen files.  For example, the TableGen name of
+    // def EAX : Register <...>; is "EAX"
+    return StringRef(getName(Reg)).lower();
+  }
+
   //===--------------------------------------------------------------------===//
   /// Subtarget Hooks
 
Index: lib/CodeGen/SelectionDAG/TargetLowering.cpp
===================================================================
--- lib/CodeGen/SelectionDAG/TargetLowering.cpp
+++ lib/CodeGen/SelectionDAG/TargetLowering.cpp
@@ -2275,7 +2275,7 @@
 
     for (TargetRegisterClass::iterator I = RC->begin(), E = RC->end();
          I != E; ++I) {
-      if (RegName.equals_lower(RI->getName(*I))) {
+      if (RegName.equals(RI->getRegAsmName(*I))) {
         std::pair<unsigned, const TargetRegisterClass*> S =
           std::make_pair(*I, RC);