diff --git a/llvm/lib/Target/PowerPC/PPCInstrInfo.h b/llvm/lib/Target/PowerPC/PPCInstrInfo.h
--- a/llvm/lib/Target/PowerPC/PPCInstrInfo.h
+++ b/llvm/lib/Target/PowerPC/PPCInstrInfo.h
@@ -191,6 +191,10 @@
   // LI8.
   bool simplifyToLI(MachineInstr &MI, MachineInstr &DefMI,
                     unsigned OpNoForForwarding, MachineInstr **KilledDef) const;
+  // If the inst is imm-form and its register operand is produced by a ADDI, put
+  // the imm into the inst directly and remove the ADDI if possible.
+  bool transformToNewImmFormFedByAdd(MachineInstr &MI, MachineInstr &DefMI,
+                                     unsigned OpNoForForwarding) const;
   // If the inst is x-form and has imm-form and one of its operand is produced
   // by a LI, put the imm into the inst directly and remove the LI if possible.
   bool transformToImmFormFedByLI(MachineInstr &MI, const ImmInstrInfo &III,
@@ -221,7 +225,8 @@
   bool isImmElgibleForForwarding(const MachineOperand &ImmMO,
                                  const MachineInstr &DefMI,
                                  const ImmInstrInfo &III,
-                                 int64_t &Imm) const;
+                                 int64_t &Imm,
+                                 int64_t BaseImm = 0) const;
   bool isRegElgibleForForwarding(const MachineOperand &RegMO,
                                  const MachineInstr &DefMI,
                                  const MachineInstr &MI, bool KillDefMI,
diff --git a/llvm/lib/Target/PowerPC/PPCInstrInfo.cpp b/llvm/lib/Target/PowerPC/PPCInstrInfo.cpp
--- a/llvm/lib/Target/PowerPC/PPCInstrInfo.cpp
+++ b/llvm/lib/Target/PowerPC/PPCInstrInfo.cpp
@@ -2563,7 +2563,8 @@
   MachineRegisterInfo *MRI = &MI.getParent()->getParent()->getRegInfo();
   const TargetRegisterInfo *TRI = &getRegisterInfo();
   // If we're in SSA, get the defs through the MRI. Otherwise, only look
-  // within the basic block to see if the register is defined using an LI/LI8.
+  // within the basic block to see if the register is defined using an
+  // LI/LI8/ADDI/ADDI8.
   if (MRI->isSSA()) {
     for (int i = 1, e = MI.getNumOperands(); i < e; i++) {
       if (!MI.getOperand(i).isReg())
@@ -2574,9 +2575,16 @@
       unsigned TrueReg = TRI->lookThruCopyLike(Reg, MRI);
       if (Register::isVirtualRegister(TrueReg)) {
         DefMI = MRI->getVRegDef(TrueReg);
-        if (DefMI->getOpcode() == PPC::LI || DefMI->getOpcode() == PPC::LI8) {
+        if (DefMI->getOpcode() == PPC::LI || DefMI->getOpcode() == PPC::LI8 ||
+            DefMI->getOpcode() == PPC::ADDI ||
+            DefMI->getOpcode() == PPC::ADDI8) {
           OpNoForForwarding = i;
-          break;
+          // The ADDI and LI operand maybe exist in one instruction at same
+          // time. we prefer to fold LI operand as LI only has one Imm operand
+          // and is more possible to be converted. So if current DefMI is
+          // ADDI/ADDI8, we continue to find possible LI/LI8.
+          if (DefMI->getOpcode() == PPC::LI || DefMI->getOpcode() == PPC::LI8)
+            break;
         }
       }
     }
@@ -2647,10 +2655,6 @@
 
 void PPCInstrInfo::fixupIsDeadOrKill(MachineInstr &StartMI, MachineInstr &EndMI,
                                      unsigned RegNo) const {
-  const MachineRegisterInfo &MRI =
-      StartMI.getParent()->getParent()->getRegInfo();
-  if (MRI.isSSA())
-    return;
 
   // Instructions between [StartMI, EndMI] should be in same basic block.
   assert((StartMI.getParent() == EndMI.getParent()) &&
@@ -2973,6 +2977,13 @@
   if (KilledDef && KillFwdDefMI)
     *KilledDef = DefMI;
 
+  // If this is a imm instruction and its register operands is produced by ADDI,
+  // put the imm into imm inst directly.
+  if (RI.getMappedIdxOpcForImmOpc(MI.getOpcode()) !=
+          PPC::INSTRUCTION_LIST_END &&
+      transformToNewImmFormFedByAdd(MI, *DefMI, ForwardingOperand))
+    return true;
+
   ImmInstrInfo III;
   bool IsVFReg = MI.getOperand(0).isReg()
                      ? isVFRegister(MI.getOperand(0).getReg())
@@ -3513,6 +3524,10 @@
   RegMO = &DefMI.getOperand(1);
   ImmMO = &DefMI.getOperand(2);
 
+  // Before RA, ADDI first operand could be a frame index.
+  if (!RegMO->isReg())
+    return false;
+
   // This DefMI is elgible for forwarding if it is:
   // 1. add inst
   // 2. one of the operands is Imm/CPI/Global.
@@ -3561,7 +3576,8 @@
 bool PPCInstrInfo::isImmElgibleForForwarding(const MachineOperand &ImmMO,
                                              const MachineInstr &DefMI,
                                              const ImmInstrInfo &III,
-                                             int64_t &Imm) const {
+                                             int64_t &Imm,
+                                             int64_t BaseImm) const {
   assert(isAnImmediateOperand(ImmMO) && "ImmMO is NOT an immediate");
   if (DefMI.getOpcode() == PPC::ADDItocL) {
     // The operand for ADDItocL is CPI, which isn't imm at compiling time,
@@ -3584,10 +3600,10 @@
 
   if (ImmMO.isImm()) {
     // It is Imm, we need to check if the Imm fit the range.
-    int64_t Immediate = ImmMO.getImm();
     // Sign-extend to 64-bits.
-    Imm = ((uint64_t)Immediate & ~0x7FFFuLL) != 0 ?
-      (Immediate | 0xFFFFFFFFFFFF0000) : Immediate;
+    // DefMI may be folded with another imm form instruction, the result Imm is
+    // the sum of Imm of DefMI and BaseImm which is from imm form instruction.
+    Imm = SignExtend64<16>(ImmMO.getImm() + BaseImm);
 
     if (Imm % III.ImmMustBeMultipleOf)
       return false;
@@ -3840,6 +3856,99 @@
   return false;
 }
 
+bool PPCInstrInfo::transformToNewImmFormFedByAdd(
+    MachineInstr &MI, MachineInstr &DefMI, unsigned OpNoForForwarding) const {
+  MachineRegisterInfo *MRI = &MI.getParent()->getParent()->getRegInfo();
+  bool PostRA = !MRI->isSSA();
+  // FIXME: extend this to post-ra. Need to do some change in getForwardingDefMI
+  // for post-ra.
+  if (PostRA)
+    return false;
+
+  // Only handle load/store.
+  if (!MI.mayLoadOrStore())
+    return false;
+
+  unsigned XFormOpcode = RI.getMappedIdxOpcForImmOpc(MI.getOpcode());
+
+  assert((XFormOpcode != PPC::INSTRUCTION_LIST_END) &&
+         "MI must have x-form opcode");
+
+  // get Imm Form info.
+  ImmInstrInfo III;
+  bool IsVFReg = MI.getOperand(0).isReg()
+                     ? isVFRegister(MI.getOperand(0).getReg())
+                     : false;
+
+  if (!instrHasImmForm(XFormOpcode, IsVFReg, III, PostRA))
+    return false;
+
+  if (!III.IsSummingOperands)
+    return false;
+
+  if (OpNoForForwarding != III.OpNoForForwarding)
+    return false;
+
+  MachineOperand ImmOperandMI = MI.getOperand(III.ImmOpNo);
+  if (!ImmOperandMI.isImm())
+    return false;
+
+  // Check DefMI.
+  MachineOperand *ImmMO = nullptr;
+  MachineOperand *RegMO = nullptr;
+  if (!isDefMIElgibleForForwarding(DefMI, III, ImmMO, RegMO))
+    return false;
+  assert(ImmMO && RegMO && "Imm and Reg operand must have been set");
+
+  // Check Imm.
+  // Set ImmBase from imm instruction as base and get new Imm inside
+  // isImmElgibleForForwarding.
+  int64_t ImmBase = ImmOperandMI.getImm();
+  int64_t Imm = 0;
+  if (!isImmElgibleForForwarding(*ImmMO, DefMI, III, Imm, ImmBase))
+    return false;
+
+  // Get killed info in case fixup needed after transformation.
+  unsigned ForwardKilledOperandReg = ~0U;
+  if (MI.getOperand(III.OpNoForForwarding).isKill())
+    ForwardKilledOperandReg = MI.getOperand(III.OpNoForForwarding).getReg();
+
+  // Do the transform
+  LLVM_DEBUG(dbgs() << "Replacing instruction:\n");
+  LLVM_DEBUG(MI.dump());
+  LLVM_DEBUG(dbgs() << "Fed by:\n");
+  LLVM_DEBUG(DefMI.dump());
+
+  MI.getOperand(III.OpNoForForwarding).setReg(RegMO->getReg());
+  MI.getOperand(III.OpNoForForwarding).setIsKill(RegMO->isKill());
+  MI.getOperand(III.ImmOpNo).setImm(Imm);
+
+  // FIXME: fix kill/dead flag if MI and DefMI are not in same basic block.
+  if (DefMI.getParent() == MI.getParent()) {
+    // Check if reg is killed between MI and DefMI.
+    auto IsKilledFor = [&](unsigned Reg) {
+      MachineBasicBlock::const_reverse_iterator It = MI;
+      MachineBasicBlock::const_reverse_iterator E = DefMI;
+      It++;
+      for (; It != E; ++It) {
+        if (It->killsRegister(Reg))
+          return true;
+      }
+      return false;
+    };
+
+    // Update kill flag
+    if (RegMO->isKill() || IsKilledFor(RegMO->getReg()))
+      fixupIsDeadOrKill(DefMI, MI, RegMO->getReg());
+    if (ForwardKilledOperandReg != ~0U)
+      fixupIsDeadOrKill(DefMI, MI, ForwardKilledOperandReg);
+  }
+
+  LLVM_DEBUG(dbgs() << "With:\n");
+  LLVM_DEBUG(MI.dump());
+  return true;
+}
+
 // If an X-Form instruction is fed by an add-immediate and one of its operands
 // is the literal zero, attempt to forward the source of the add-immediate to
 // the corresponding D-Form instruction with the displacement coming from
diff --git a/llvm/test/CodeGen/PowerPC/convert-ri-addi-to-ri.mir b/llvm/test/CodeGen/PowerPC/convert-ri-addi-to-ri.mir
new file mode 100644
--- /dev/null
+++ b/llvm/test/CodeGen/PowerPC/convert-ri-addi-to-ri.mir
@@ -0,0 +1,67 @@
+# RUN: llc -mtriple=powerpc64le-unknown-linux-gnu -verify-machineinstrs \
+# RUN:   -run-pass ppc-mi-peepholes -ppc-convert-rr-to-ri %s -o - | FileCheck %s
+
+---
+name: foldNewDformStore
+# CHECK: name: foldNewDformStore
+tracksRegLiveness: true
+body:             |
+  bb.0.entry:
+    liveins: $x3
+
+    %0:g8rc_and_g8rc_nox0 = COPY $x3
+    %1:g8rc_and_g8rc_nox0 = ADDI8 %0:g8rc_and_g8rc_nox0, 144
+    %2:g8rc = LI8 0
+    ; CHECK: STD killed %2, 160, %0
+    STD killed %2:g8rc, 16, %1:g8rc_and_g8rc_nox0
+    BLR8 implicit $lr8, implicit $rm
+...
+---
+name: foldNewDformStoreAlignNotMatch
+# CHECK: name: foldNewDformStoreAlignNotMatch
+tracksRegLiveness: true
+body:             |
+  bb.0.entry:
+    liveins: $x3
+
+    %0:g8rc_and_g8rc_nox0 = COPY $x3
+    %1:g8rc_and_g8rc_nox0 = ADDI8 %0:g8rc_and_g8rc_nox0, 141
+    %2:g8rc = LI8 0
+    ; CHECK: STD killed %2, 16, %1
+    STD killed %2:g8rc, 16, %1:g8rc_and_g8rc_nox0
+    BLR8 implicit $lr8, implicit $rm
+...
+---
+name: foldNewDformStoreKilledFlag
+# CHECK: name: foldNewDformStoreKilledFlag
+tracksRegLiveness: true
+body:             |
+  bb.0.entry:
+    liveins: $x3
+
+    %0:g8rc_and_g8rc_nox0 = COPY $x3
+    %1:g8rc_and_g8rc_nox0 = ADDI8 %0:g8rc_and_g8rc_nox0, 144
+    %2:g8rc = LI8 0
+    ; CHECK: STD %1, 0, %0
+    STD %1:g8rc_and_g8rc_nox0, 0, killed %0:g8rc_and_g8rc_nox0
+    ; CHECK: STD killed %2, 160, killed %0
+    STD killed %2:g8rc, 16, %1:g8rc_and_g8rc_nox0
+    BLR8 implicit $lr8, implicit $rm
+...
+---
+name: foldNewDformPreferLIOperand
+# CHECK: name: foldNewDformPreferLIOperand
+tracksRegLiveness: true
+body:             |
+  bb.0.entry:
+  liveins: $x3
+  %0:g8rc_and_g8rc_nox0 = COPY $x3
+  %1:g8rc = ADDI8 %0:g8rc_and_g8rc_nox0, 1
+  %2:g8rc = LI8 1
+  ; CHECK: SUBFIC8 killed %1, 1, implicit-def $carry
+  %3:g8rc = SUBFC8 killed %1:g8rc, %2:g8rc, implicit-def $carry
+  %4:g8rc = SUBFE8 %2:g8rc, %2:g8rc, implicit-def dead $carry, implicit $carry
+  %5:g8rc = NEG8 killed %4:g8rc
+  $x3 = COPY %5:g8rc
+  BLR8 implicit $lr8, implicit $rm, implicit $x3
+...