Index: llvm/include/llvm/CodeGen/TargetRegisterInfo.h
===================================================================
--- llvm/include/llvm/CodeGen/TargetRegisterInfo.h
+++ llvm/include/llvm/CodeGen/TargetRegisterInfo.h
@@ -578,6 +578,14 @@
     return false;
   }
 
+  // Return true if the register is needed for returning from the
+  // function and so must be preserved in the callee even if preserved
+  // by the caller
+  virtual bool isNeededForReturn(MCRegister PhysReg,
+                                 const MachineFunction &MF) const {
+    return false;
+  }
+
   /// Prior to adding the live-out mask to a stackmap or patchpoint
   /// instruction, provide the target the opportunity to adjust it (mainly to
   /// remove pseudo-registers that should be ignored).
Index: llvm/lib/CodeGen/TargetFrameLoweringImpl.cpp
===================================================================
--- llvm/lib/CodeGen/TargetFrameLoweringImpl.cpp
+++ llvm/lib/CodeGen/TargetFrameLoweringImpl.cpp
@@ -92,10 +92,9 @@
 
   // When interprocedural register allocation is enabled caller saved registers
   // are preferred over callee saved registers.
-  if (MF.getTarget().Options.EnableIPRA &&
-      isSafeForNoCSROpt(MF.getFunction()) &&
-      isProfitableForNoCSROpt(MF.getFunction()))
-    return;
+  bool NoCSR = (MF.getTarget().Options.EnableIPRA &&
+                isSafeForNoCSROpt(MF.getFunction()) &&
+                isProfitableForNoCSROpt(MF.getFunction()));
 
   // Get the callee saved register list...
   const MCPhysReg *CSRegs = MF.getRegInfo().getCalleeSavedRegs();
@@ -124,10 +123,12 @@
   // Functions which call __builtin_unwind_init get all their registers saved.
   bool CallsUnwindInit = MF.callsUnwindInit();
   const MachineRegisterInfo &MRI = MF.getRegInfo();
+  const TargetRegisterInfo *RI = MF.getSubtarget().getRegisterInfo();
   for (unsigned i = 0; CSRegs[i]; ++i) {
     unsigned Reg = CSRegs[i];
     if (CallsUnwindInit || MRI.isPhysRegModified(Reg))
-      SavedRegs.set(Reg);
+      if (!NoCSR || !MRI.isAllocatable(Reg) || RI->isNeededForReturn(Reg, MF))
+        SavedRegs.set(Reg);
   }
 }
 
Index: llvm/lib/Target/Mips/MipsRegisterInfo.h
===================================================================
--- llvm/lib/Target/Mips/MipsRegisterInfo.h
+++ llvm/lib/Target/Mips/MipsRegisterInfo.h
@@ -72,6 +72,9 @@
   /// Return GPR register class.
   virtual const TargetRegisterClass *intRegClass(unsigned Size) const = 0;
 
+  virtual bool isNeededForReturn(MCRegister PhysReg,
+                                 const MachineFunction &MF) const override;
+
 private:
   virtual void eliminateFI(MachineBasicBlock::iterator II, unsigned OpNo,
                            int FrameIndex, uint64_t StackSize,
Index: llvm/lib/Target/Mips/MipsRegisterInfo.cpp
===================================================================
--- llvm/lib/Target/Mips/MipsRegisterInfo.cpp
+++ llvm/lib/Target/Mips/MipsRegisterInfo.cpp
@@ -244,6 +244,11 @@
   return true;
 }
 
+bool MipsRegisterInfo::isNeededForReturn(MCRegister PhysReg,
+                                         const MachineFunction &MF) const {
+  return PhysReg == Mips::RA || PhysReg == Mips::RA_64;
+}
+
 // FrameIndex represent objects inside a abstract stack.
 // We must replace FrameIndex with an stack/frame pointer
 // direct reference.