diff --git a/llvm/lib/Target/RISCV/RISCVISelDAGToDAG.cpp b/llvm/lib/Target/RISCV/RISCVISelDAGToDAG.cpp
--- a/llvm/lib/Target/RISCV/RISCVISelDAGToDAG.cpp
+++ b/llvm/lib/Target/RISCV/RISCVISelDAGToDAG.cpp
@@ -74,6 +74,32 @@
   EVT VT = Node->getValueType(0);
 
   switch (Opcode) {
+  // Optimize the node (add r, imm) to (addi (addi r, imm0) imm1)
+  // if possible.
+  case ISD::ADD: {
+    // The second operand must be an immediate.
+    if (auto *ConstOp = dyn_cast<ConstantSDNode>(Node->getOperand(1))) {
+      // The immediate operand must not have other use.
+      if (!ConstOp->hasOneUse())
+        break;
+      // The immediate must be in range [-4095,-2049] or [2048,4094].
+      int64_t ImmVal = ConstOp->getSExtValue();
+      if (ImmVal < -4095 || (-2049 < ImmVal && ImmVal < 2048) || 4094 < ImmVal)
+        break;
+      // Break the immediate to Imm0+Imm1.
+      SDLoc DL(Node);
+      EVT VT = Node->getValueType(0);
+      SDValue ImmOp0 = CurDAG->getTargetConstant(ImmVal / 2, DL, VT);
+      SDValue ImmOp1 = CurDAG->getTargetConstant(ImmVal - ImmVal / 2, DL, VT);
+      auto *NodeAddi0 = CurDAG->getMachineNode(RISCV::ADDI, DL, VT,
+                                               Node->getOperand(0), ImmOp0);
+      auto *NodeAddi1 = CurDAG->getMachineNode(RISCV::ADDI, DL, VT,
+                                               SDValue(NodeAddi0, 0), ImmOp1);
+      ReplaceNode(Node, NodeAddi1);
+      return;
+    }
+    break;
+  }
   case ISD::Constant: {
     auto ConstNode = cast<ConstantSDNode>(Node);
     if (VT == XLenVT && ConstNode->isNullValue()) {
diff --git a/llvm/test/CodeGen/RISCV/add-imm.ll b/llvm/test/CodeGen/RISCV/add-imm.ll
new file mode 100644
--- /dev/null
+++ b/llvm/test/CodeGen/RISCV/add-imm.ll
@@ -0,0 +1,165 @@
+; NOTE: Assertions have been autogenerated by utils/update_llc_test_checks.py
+; RUN: llc -mtriple=riscv32 -verify-machineinstrs < %s \
+; RUN:   | FileCheck -check-prefix=RV32I %s
+; RUN: llc -mtriple=riscv64 -verify-machineinstrs < %s \
+; RUN:   | FileCheck -check-prefix=RV64I %s
+
+; These test how the immediate in an addition is materialized.
+
+define i32 @add32_0(i32 %a) nounwind {
+; RV32I-LABEL: add32_0:
+; RV32I:       # %bb.0:
+; RV32I-NEXT:    addi a0, a0, 2047
+; RV32I-NEXT:    ret
+  %1 = add i32 %a, 2047
+  ret i32 %1
+}
+
+define i64 @add64_0(i64 %a) nounwind {
+; RV64I-LABEL: add64_0:
+; RV64I:       # %bb.0:
+; RV64I-NEXT:    addi a0, a0, 2047
+; RV64I-NEXT:    ret
+  %1 = add i64 %a, 2047
+  ret i64 %1
+}
+
+define i32 @add32_1(i32 %a) nounwind {
+; RV32I-LABEL: add32_1:
+; RV32I:       # %bb.0:
+; RV32I-NEXT:    addi a0, a0, 1024
+; RV32I-NEXT:    addi a0, a0, 1024
+; RV32I-NEXT:    ret
+  %1 = add i32 %a, 2048
+  ret i32 %1
+}
+
+define i64 @add64_1(i64 %a) nounwind {
+; RV64I-LABEL: add64_1:
+; RV64I:       # %bb.0:
+; RV64I-NEXT:    addi a0, a0, 1024
+; RV64I-NEXT:    addi a0, a0, 1024
+; RV64I-NEXT:    ret
+  %1 = add i64 %a, 2048
+  ret i64 %1
+}
+
+define i32 @add32_2(i32 %a) nounwind {
+; RV32I-LABEL: add32_2:
+; RV32I:       # %bb.0:
+; RV32I-NEXT:    addi a0, a0, 2047
+; RV32I-NEXT:    addi a0, a0, 2047
+; RV32I-NEXT:    ret
+  %1 = add i32 %a, 4094
+  ret i32 %1
+}
+
+define i64 @add64_2(i64 %a) nounwind {
+; RV64I-LABEL: add64_2:
+; RV64I:       # %bb.0:
+; RV64I-NEXT:    addi a0, a0, 2047
+; RV64I-NEXT:    addi a0, a0, 2047
+; RV64I-NEXT:    ret
+  %1 = add i64 %a, 4094
+  ret i64 %1
+}
+
+define i32 @add32_3(i32 %a) nounwind {
+; RV32I-LABEL: add32_3:
+; RV32I:       # %bb.0:
+; RV32I-NEXT:    lui a1, 1
+; RV32I-NEXT:    addi a1, a1, -1
+; RV32I-NEXT:    add a0, a0, a1
+; RV32I-NEXT:    ret
+  %1 = add i32 %a, 4095
+  ret i32 %1
+}
+
+define i64 @add64_3(i64 %a) nounwind {
+; RV64I-LABEL: add64_3:
+; RV64I:       # %bb.0:
+; RV64I-NEXT:    lui a1, 1
+; RV64I-NEXT:    addiw a1, a1, -1
+; RV64I-NEXT:    add a0, a0, a1
+; RV64I-NEXT:    ret
+  %1 = add i64 %a, 4095
+  ret i64 %1
+}
+
+define i32 @add32_4(i32 %a) nounwind {
+; RV32I-LABEL: add32_4:
+; RV32I:       # %bb.0:
+; RV32I-NEXT:    addi a0, a0, -2048
+; RV32I-NEXT:    ret
+  %1 = add i32 %a, -2048
+  ret i32 %1
+}
+
+define i64 @add64_4(i64 %a) nounwind {
+; RV64I-LABEL: add64_4:
+; RV64I:       # %bb.0:
+; RV64I-NEXT:    addi a0, a0, -2048
+; RV64I-NEXT:    ret
+  %1 = add i64 %a, -2048
+  ret i64 %1
+}
+
+define i32 @add32_5(i32 %a) nounwind {
+; RV32I-LABEL: add32_5:
+; RV32I:       # %bb.0:
+; RV32I-NEXT:    addi a0, a0, -1024
+; RV32I-NEXT:    addi a0, a0, -1025
+; RV32I-NEXT:    ret
+  %1 = add i32 %a, -2049
+  ret i32 %1
+}
+
+define i64 @add64_5(i64 %a) nounwind {
+; RV64I-LABEL: add64_5:
+; RV64I:       # %bb.0:
+; RV64I-NEXT:    addi a0, a0, -1024
+; RV64I-NEXT:    addi a0, a0, -1025
+; RV64I-NEXT:    ret
+  %1 = add i64 %a, -2049
+  ret i64 %1
+}
+
+define i32 @add32_6(i32 %a) nounwind {
+; RV32I-LABEL: add32_6:
+; RV32I:       # %bb.0:
+; RV32I-NEXT:    addi a0, a0, -2047
+; RV32I-NEXT:    addi a0, a0, -2048
+; RV32I-NEXT:    ret
+  %1 = add i32 %a, -4095
+  ret i32 %1
+}
+
+define i64 @add64_6(i64 %a) nounwind {
+; RV64I-LABEL: add64_6:
+; RV64I:       # %bb.0:
+; RV64I-NEXT:    addi a0, a0, -2047
+; RV64I-NEXT:    addi a0, a0, -2048
+; RV64I-NEXT:    ret
+  %1 = add i64 %a, -4095
+  ret i64 %1
+}
+
+define i32 @add32_7(i32 %a) nounwind {
+; RV32I-LABEL: add32_7:
+; RV32I:       # %bb.0:
+; RV32I-NEXT:    lui a1, 1048575
+; RV32I-NEXT:    add a0, a0, a1
+; RV32I-NEXT:    ret
+  %1 = add i32 %a, -4096
+  ret i32 %1
+}
+
+define i64 @add64_7(i64 %a) nounwind {
+; RV64I-LABEL: add64_7:
+; RV64I:       # %bb.0:
+; RV64I-NEXT:    lui a1, 1048575
+; RV64I-NEXT:    add a0, a0, a1
+; RV64I-NEXT:    ret
+  %1 = add i64 %a, -4096
+  ret i64 %1
+}