diff --git a/llvm/include/llvm/CodeGen/Register.h b/llvm/include/llvm/CodeGen/Register.h
--- a/llvm/include/llvm/CodeGen/Register.h
+++ b/llvm/include/llvm/CodeGen/Register.h
@@ -110,6 +110,15 @@
     return MCRegister(Reg);
   }
 
+  /// Utility to check-convert this value to a MCRegister. The caller is
+  /// expected to have already validated that this Register is, indeed,
+  /// physical.
+  MCRegister asMCReg() const {
+    assert(Reg == MCRegister::NoRegister ||
+           MCRegister::isPhysicalRegister(Reg));
+    return MCRegister(Reg);
+  }
+
   bool isValid() const { return Reg != MCRegister::NoRegister; }
 
   /// Comparisons between register objects
diff --git a/llvm/include/llvm/MC/MCRegister.h b/llvm/include/llvm/MC/MCRegister.h
--- a/llvm/include/llvm/MC/MCRegister.h
+++ b/llvm/include/llvm/MC/MCRegister.h
@@ -68,6 +68,12 @@
     return Reg;
   }
 
+  /// Check the provided unsigned value is a valid MCRegister.
+  static MCRegister from(unsigned Val) {
+    assert(Val == NoRegister || isPhysicalRegister(Val));
+    return MCRegister(Val);
+  }
+
   unsigned id() const {
     return Reg;
   }
diff --git a/llvm/include/llvm/MC/MCRegisterInfo.h b/llvm/include/llvm/MC/MCRegisterInfo.h
--- a/llvm/include/llvm/MC/MCRegisterInfo.h
+++ b/llvm/include/llvm/MC/MCRegisterInfo.h
@@ -675,6 +675,7 @@
 
   MCRegUnitIterator(MCRegister Reg, const MCRegisterInfo *MCRI) {
     assert(Reg && "Null register has no regunits");
+    assert(MCRegister::isPhysicalRegister(Reg.id()));
     // Decode the RegUnits MCRegisterDesc field.
     unsigned RU = MCRI->get(Reg).RegUnits;
     unsigned Scale = RU & 15;