diff --git a/llvm/lib/Target/RISCV/RISCVFrameLowering.cpp b/llvm/lib/Target/RISCV/RISCVFrameLowering.cpp
--- a/llvm/lib/Target/RISCV/RISCVFrameLowering.cpp
+++ b/llvm/lib/Target/RISCV/RISCVFrameLowering.cpp
@@ -329,7 +329,6 @@
                                            MachineInstr::MIFlag Flag) const {
   assert(Amount != 0 && "Did not need to adjust stack pointer for RVV.");
 
-  const RISCVInstrInfo *TII = STI.getInstrInfo();
   const Register SPReg = getSPReg(STI);
 
   // Optimize compile time offset case
@@ -348,20 +347,9 @@
     return;
   }
 
-  unsigned Opc = RISCV::ADD;
-  if (Amount < 0) {
-    Amount = -Amount;
-    Opc = RISCV::SUB;
-  }
-  // 1. Multiply the number of v-slots to the length of registers
-  Register FactorRegister =
-      MF.getRegInfo().createVirtualRegister(&RISCV::GPRRegClass);
-  TII->getVLENFactoredAmount(MF, MBB, MBBI, DL, FactorRegister, Amount, Flag);
-  // 2. SP = SP - RVV stack size
-  BuildMI(MBB, MBBI, DL, TII->get(Opc), SPReg)
-      .addReg(SPReg)
-      .addReg(FactorRegister, RegState::Kill)
-      .setMIFlag(Flag);
+  const RISCVRegisterInfo &RI = *STI.getRegisterInfo();
+  RI.adjustReg(MBB, MBBI, DL, SPReg, SPReg, StackOffset::getScalable(Amount),
+               Flag);
 }
 
 void RISCVFrameLowering::emitPrologue(MachineFunction &MF,
diff --git a/llvm/lib/Target/RISCV/RISCVRegisterInfo.h b/llvm/lib/Target/RISCV/RISCVRegisterInfo.h
--- a/llvm/lib/Target/RISCV/RISCVRegisterInfo.h
+++ b/llvm/lib/Target/RISCV/RISCVRegisterInfo.h
@@ -49,8 +49,9 @@
                  MaybeAlign RequiredAlign, bool KillSrcReg) const;
 
   // Update DestReg to have the value of SrcReg plus an Offset.
-  void adjustReg(MachineBasicBlock::iterator II, Register DestReg,
-                 Register SrcReg, StackOffset Offset) const;
+  void adjustReg(MachineBasicBlock &MBB, MachineBasicBlock::iterator II,
+                 const DebugLoc &DL, Register DestReg, Register SrcReg,
+                 StackOffset Offset, MachineInstr::MIFlag Flag) const;
 
   bool eliminateFrameIndex(MachineBasicBlock::iterator MI, int SPAdj,
                            unsigned FIOperandNum,
diff --git a/llvm/lib/Target/RISCV/RISCVRegisterInfo.cpp b/llvm/lib/Target/RISCV/RISCVRegisterInfo.cpp
--- a/llvm/lib/Target/RISCV/RISCVRegisterInfo.cpp
+++ b/llvm/lib/Target/RISCV/RISCVRegisterInfo.cpp
@@ -220,18 +220,19 @@
       .setMIFlag(Flag);
 }
 
-void RISCVRegisterInfo::adjustReg(MachineBasicBlock::iterator II, Register DestReg,
-                                  Register SrcReg, StackOffset Offset) const {
+void RISCVRegisterInfo::adjustReg(MachineBasicBlock &MBB,
+                                  MachineBasicBlock::iterator II,
+                                  const DebugLoc &DL, Register DestReg,
+                                  Register SrcReg, StackOffset Offset,
+                                  MachineInstr::MIFlag Flag) const {
 
   if (DestReg == SrcReg && !Offset.getFixed() && !Offset.getScalable())
     return;
 
-  MachineInstr &MI = *II;
-  MachineFunction &MF = *MI.getParent()->getParent();
+  MachineFunction &MF = *MBB.getParent();
+  MachineRegisterInfo &MRI = MF.getRegInfo();
   const RISCVSubtarget &ST = MF.getSubtarget<RISCVSubtarget>();
   const RISCVInstrInfo *TII = ST.getInstrInfo();
-  DebugLoc DL = MI.getDebugLoc();
-  MachineBasicBlock &MBB = *MI.getParent();
 
   bool SrcRegIsKill = false;
 
@@ -243,16 +244,20 @@
       ScalableAdjOpc = RISCV::SUB;
     }
     // Get vlenb and multiply vlen with the number of vector registers.
-    TII->getVLENFactoredAmount(MF, MBB, II, DL, DestReg, ScalableValue);
+    Register ScratchReg = DestReg;
+    if (DestReg == SrcReg)
+      ScratchReg = MRI.createVirtualRegister(&RISCV::GPRRegClass);
+    TII->getVLENFactoredAmount(MF, MBB, II, DL, ScratchReg, ScalableValue, Flag);
     BuildMI(MBB, II, DL, TII->get(ScalableAdjOpc), DestReg)
-      .addReg(SrcReg).addReg(DestReg, RegState::Kill);
+      .addReg(SrcReg).addReg(ScratchReg, RegState::Kill)
+      .setMIFlag(Flag);
     SrcReg = DestReg;
     SrcRegIsKill = true;
   }
 
   if (Offset.getFixed())
     adjustReg(MBB, II, DL, DestReg, SrcReg, Offset.getFixed(),
-              MachineInstr::NoFlags, None, SrcRegIsKill);
+              Flag, None, SrcRegIsKill);
 }
 
 
@@ -313,7 +318,8 @@
       DestReg = MI.getOperand(0).getReg();
     else
       DestReg = MRI.createVirtualRegister(&RISCV::GPRRegClass);
-    adjustReg(II, DestReg, FrameReg, Offset);
+    adjustReg(*II->getParent(), II, DL, DestReg, FrameReg, Offset,
+              MachineInstr::NoFlags);
     MI.getOperand(FIOperandNum).ChangeToRegister(DestReg, /*IsDef*/false,
                                                  /*IsImp*/false,
                                                  /*IsKill*/true);