diff --git a/llvm/lib/Target/RISCV/RISCVTargetTransformInfo.cpp b/llvm/lib/Target/RISCV/RISCVTargetTransformInfo.cpp
--- a/llvm/lib/Target/RISCV/RISCVTargetTransformInfo.cpp
+++ b/llvm/lib/Target/RISCV/RISCVTargetTransformInfo.cpp
@@ -11,6 +11,7 @@
 #include "llvm/Analysis/TargetTransformInfo.h"
 #include "llvm/CodeGen/BasicTTIImpl.h"
 #include "llvm/CodeGen/TargetLowering.h"
+#include "llvm/IR/PatternMatch.h"
 #include <cmath>
 using namespace llvm;
 
@@ -38,6 +39,34 @@
                                     getST()->getFeatureBits());
 }
 
+// Recognize (ashr (add (shl X, 32), C << 32), 32) which DAGCombine can turn
+// into (addw X, C). If we hoist the constant, DAGCombine can't see the pattern.
+// The shl could also be a mul with -(1 << 32). The add can also be a sub with
+// a constant left hand side. We assume InstCombine canonicalized the add/sub.
+static bool isShiftedADDWOrSUBW(Instruction *Inst, const APInt &Imm) {
+  using namespace PatternMatch;
+  if (Inst->getOpcode() != Instruction::Add &&
+      Inst->getOpcode() != Instruction::Sub)
+    return false;
+  // Needs to be a 64-bit immediate with at least 32 trailing zeros.
+  if (Imm.getBitWidth() != 64 || Imm.countTrailingZeros() < 32)
+    return false;
+  unsigned ShlIdx = Inst->getOpcode() == Instruction::Add ? 0 : 1;
+  Value *ShlOp = Inst->getOperand(ShlIdx);
+  // Non-immediate source should be a shl by 32 or a mul by -(1 << 32).
+  if (!match(ShlOp, m_Shl(m_Value(), m_SpecificInt(32))) &&
+      !match(ShlOp, m_Mul(m_Value(), m_SpecificInt(-1ULL << 32))))
+    return false;
+  BasicBlock *BB = Inst->getParent();
+  // Need to be in the same basic block.
+  if (cast<Instruction>(ShlOp)->getParent() != BB)
+    return false;
+  // User should be an ashr by 32.
+  return Inst->hasOneUse() &&
+         match(*Inst->user_begin(), m_AShr(m_Value(), m_SpecificInt(32))) &&
+         cast<Instruction>(*Inst->user_begin())->getParent() == BB;
+}
+
 InstructionCost RISCVTTIImpl::getIntImmCostInst(unsigned Opcode, unsigned Idx,
                                                 const APInt &Imm, Type *Ty,
                                                 TTI::TargetCostKind CostKind,
@@ -91,6 +120,9 @@
     break;
   }
 
+  if (Inst && ST->is64Bit() && isShiftedADDWOrSUBW(Inst, Imm))
+    return TTI::TCC_Free;
+
   if (Takes12BitImm) {
     // Check immediate is the correct argument...
     if (Instruction::isCommutative(Opcode) || Idx == ImmArgIdx) {
diff --git a/llvm/test/Transforms/ConstantHoisting/RISCV/immediates.ll b/llvm/test/Transforms/ConstantHoisting/RISCV/immediates.ll
--- a/llvm/test/Transforms/ConstantHoisting/RISCV/immediates.ll
+++ b/llvm/test/Transforms/ConstantHoisting/RISCV/immediates.ll
@@ -1,5 +1,5 @@
 ; RUN: opt -mtriple=riscv32-unknown-elf -S -consthoist < %s | FileCheck %s
-; RUN: opt -mtriple=riscv64-unknown-elf -S -consthoist < %s | FileCheck %s
+; RUN: opt -mtriple=riscv64-unknown-elf -S -consthoist < %s | FileCheck %s --check-prefixes=CHECK,RV64
 
 ; Check that we don't hoist immediates with small values.
 define i64 @test1(i64 %a) nounwind {
@@ -81,3 +81,61 @@
   %2 = mul i64 %1, -4294967296
   ret i64 %2
 }
+
+; The mul is equivalent to (neg (shl X, 32)). The mul+add+ashr can be replaced
+; with subw using a much smaller constant.
+define i64 @test10(i64 %a) nounwind {
+; RV64-LABEL: test10
+; RV64: add i64 %1, 4294967296
+; RV64: add i64 %4, 4294967296
+  %1 = mul i64 %a, -4294967296
+  %2 = add i64 %1, 4294967296
+  %3 = ashr i64 %1, 32
+  %4 = mul i64 %3, -4294967296
+  %5 = add i64 %4, 4294967296
+  %6 = ashr i64 %5, 32
+  ret i64 %6
+}
+
+; The mul is equivalent to (neg (shl X, 32)). The mul+sub+ashr can be replaced
+; with addw using a much smaller constant.
+define i64 @test11(i64 %a) nounwind {
+; RV64-LABEL: test11
+; RV64: sub i64 4294967296, %1
+; RV64: sub i64 4294967296, %4
+  %1 = mul i64 %a, -4294967296
+  %2 = sub i64 4294967296, %1
+  %3 = ashr i64 %1, 32
+  %4 = mul i64 %3, -4294967296
+  %5 = sub i64 4294967296, %4
+  %6 = ashr i64 %5, 32
+  ret i64 %6
+}
+
+; The shl+add+ashr can be replaced with subw using a much smaller constant.
+define i64 @test12(i64 %a) nounwind {
+; RV64-LABEL: test12
+; RV64: add i64 %1, 4294967296
+; RV64: add i64 %4, 4294967296
+  %1 = shl i64 %a, 32
+  %2 = add i64 %1, 4294967296
+  %3 = ashr i64 %1, 32
+  %4 = shl i64 %3, 32
+  %5 = add i64 %4, 4294967296
+  %6 = ashr i64 %5, 32
+  ret i64 %6
+}
+
+; The shl+shl+ashr can be replaced with addw using a much smaller constant.
+define i64 @test13(i64 %a) nounwind {
+; RV64-LABEL: test13
+; RV64: sub i64 4294967296, %1
+; RV64: sub i64 4294967296, %4
+  %1 = shl i64 %a, 32
+  %2 = sub i64 4294967296, %1
+  %3 = ashr i64 %1, 32
+  %4 = shl i64 %3, 32
+  %5 = sub i64 4294967296, %4
+  %6 = ashr i64 %5, 32
+  ret i64 %6
+}