Index: lib/CodeGen/AsmPrinter/AsmPrinter.cpp
===================================================================
--- lib/CodeGen/AsmPrinter/AsmPrinter.cpp
+++ lib/CodeGen/AsmPrinter/AsmPrinter.cpp
@@ -27,6 +27,7 @@
 #include "llvm/CodeGen/MachineJumpTableInfo.h"
 #include "llvm/CodeGen/MachineLoopInfo.h"
 #include "llvm/CodeGen/MachineModuleInfoImpls.h"
+#include "llvm/CodeGen/MachineOperand.h"
 #include "llvm/IR/DataLayout.h"
 #include "llvm/IR/DebugInfo.h"
 #include "llvm/IR/Mangler.h"
@@ -625,6 +626,7 @@
 static void emitComments(const MachineInstr &MI, raw_ostream &CommentOS) {
   const MachineFunction *MF = MI.getParent()->getParent();
   const TargetInstrInfo *TII = MF->getSubtarget().getInstrInfo();
+  const TargetRegisterInfo *TRI = MF->getSubtarget().getRegisterInfo();
 
   // Check for spills and reloads
   int FI;
@@ -655,6 +657,23 @@
   // Check for spill-induced copies
   if (MI.getAsmPrinterFlag(MachineInstr::ReloadReuse))
     CommentOS << " Reload Reuse\n";
+
+  if (MI.isCall()) {
+    const uint32_t *CalleeRegMask;
+    CommentOS << "Call Preserved Registers: ";
+
+    for (const MachineOperand &MO : MI.operands())
+      if (MO.isRegMask()) {
+        CalleeRegMask = MO.getRegMask();
+        break;
+      }
+
+    for (unsigned PReg = 1, PRegE = TRI->getNumRegs(); PReg < PRegE; ++PReg) {
+      if (!MachineOperand::clobbersPhysReg(CalleeRegMask, PReg))
+        CommentOS << TRI->getName(PReg) << " ";
+    }
+    CommentOS << "\n";
+  }
 }
 
 /// emitImplicitDef - This method emits the specified machine instruction
Index: lib/CodeGen/RegUsageInfoCollector.cpp
===================================================================
--- lib/CodeGen/RegUsageInfoCollector.cpp
+++ lib/CodeGen/RegUsageInfoCollector.cpp
@@ -86,8 +86,7 @@
 
 bool RegUsageInfoCollector::runOnMachineFunction(MachineFunction &MF) {
   MachineRegisterInfo *MRI = &MF.getRegInfo();
-  TargetRegisterInfo *TRI =
-      (TargetRegisterInfo *)MF.getSubtarget().getRegisterInfo();
+  const TargetRegisterInfo *TRI = MF.getSubtarget().getRegisterInfo();
   const TargetMachine &TM = MF.getTarget();
 
   DEBUG(dbgs() << " -------------------- " << getPassName()
@@ -107,17 +106,31 @@
   PRUI->setTargetMachine(&TM);
 
   DEBUG(dbgs() << "Clobbered Registers: ");
-  for (unsigned PReg = 1, PRegE = TRI->getNumRegs(); PReg < PRegE; ++PReg) {
+  for (unsigned PReg = 1, PRegE = TRI->getNumRegs(); PReg < PRegE; ++PReg)
     if (!MRI->reg_nodbg_empty(PReg) && MRI->isPhysRegUsed(PReg))
       markRegClobbered(TRI, &RegMask[0], PReg);
-  }
 
   const uint32_t *CallPreservedMask =
       TRI->getCallPreservedMask(MF, MF.getFunction()->getCallingConv());
   // Set callee saved register as preserved.
-  for (unsigned index = 0; index < regMaskSize; index++) {
+  for (unsigned index = 0; index < regMaskSize; index++)
     RegMask[index] = RegMask[index] | CallPreservedMask[index];
+
+  for (MachineBasicBlock &MBB : MF) {
+    for (MachineInstr &MI : MBB) {
+      if (!MI.isCall())
+        continue;
+      for (MachineOperand &MO : MI.operands()) {
+        if (MO.isRegMask()) {
+          const uint32_t *CalleeRegMask = MO.getRegMask();
+          for (unsigned index = 0; index < regMaskSize; index++)
+            RegMask[index] = RegMask[index] & CalleeRegMask[index];
+          break;
+        }
+      }
+    }
   }
+
   for (unsigned PReg = 1, PRegE = TRI->getNumRegs(); PReg < PRegE; ++PReg) {
     if (MachineOperand::clobbersPhysReg(&(RegMask[0]), PReg))
       DEBUG(dbgs() << TRI->getName(PReg) << " ");