diff --git a/lib/Target/MRegisterInfo.cpp b/lib/Target/MRegisterInfo.cpp
new file mode 100644
index 00000000000..c47bb45440b
--- /dev/null
+++ b/lib/Target/MRegisterInfo.cpp
@@ -0,0 +1,32 @@
+//===- MRegisterInfo.cpp - Target Register Information Implementation -----===//
+//
+// This file implements the MRegisterInfo interface.
+//
+//===----------------------------------------------------------------------===//
+
+#include "llvm/Target/MRegisterInfo.h"
+
+MRegisterInfo::MRegisterInfo(const MRegisterDesc *D, unsigned NR,
+                             regclass_iterator RCB, regclass_iterator RCE)
+  : Desc(D), NumRegs(NR), RegClassBegin(RCB), RegClassEnd(RCE) {
+  assert(NumRegs < FirstVirtualRegister &&
+         "Target has too many physical registers!");
+
+  PhysRegClasses = new const TargetRegisterClass*[NumRegs];
+  for (unsigned i = 0; i != NumRegs; ++i)
+    PhysRegClasses[i] = 0;
+
+  // Fill in the PhysRegClasses map
+  for (MRegisterInfo::regclass_iterator I = regclass_begin(),
+         E = regclass_end(); I != E; ++I)
+    for (unsigned i=0; i < (*I)->getNumRegs(); ++i) {
+      assert(PhysRegClasses[(*I)->getRegister(i)] == 0 &&
+             "Register in more than one class?");
+      PhysRegClasses[(*I)->getRegister(i)] = *I;
+    }
+}
+
+
+MRegisterInfo::~MRegisterInfo() {
+  delete[] PhysRegClasses;
+}