diff --git a/llvm/lib/Target/RISCV/RISCVISelDAGToDAG.h b/llvm/lib/Target/RISCV/RISCVISelDAGToDAG.h
--- a/llvm/lib/Target/RISCV/RISCVISelDAGToDAG.h
+++ b/llvm/lib/Target/RISCV/RISCVISelDAGToDAG.h
@@ -59,6 +59,7 @@
   bool selectZExti32(SDValue N, SDValue &Val);
 
   bool hasAllNBitUsers(SDNode *Node, unsigned Bits) const;
+  bool hasAllHUsers(SDNode *Node) const { return hasAllNBitUsers(Node, 16); }
   bool hasAllWUsers(SDNode *Node) const { return hasAllNBitUsers(Node, 32); }
 
   bool selectVLOp(SDValue N, SDValue &VL);
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
@@ -459,8 +459,18 @@
       ReplaceNode(Node, New.getNode());
       return;
     }
-    ReplaceNode(Node,
-                selectImm(CurDAG, DL, ConstNode->getSExtValue(), *Subtarget));
+    int64_t Imm = ConstNode->getSExtValue();
+    // If the upper XLen-16 bits are not used, try to convert this to a simm12
+    // by sign extending bit 15.
+    if (isUInt<16>(Imm) && isInt<12>(SignExtend64(Imm, 16)) &&
+        hasAllHUsers(Node))
+      Imm = SignExtend64(Imm, 16);
+    // If the upper 32-bits are not used try to convert this into a simm32 by
+    // sign extending bit 32.
+    if (!isInt<32>(Imm) && isUInt<32>(Imm) && hasAllWUsers(Node))
+      Imm = SignExtend64(Imm, 32);
+
+    ReplaceNode(Node, selectImm(CurDAG, DL, Imm, *Subtarget));
     return;
   }
   case ISD::FrameIndex: {
@@ -1509,7 +1519,8 @@
 // opportunities.
 bool RISCVDAGToDAGISel::hasAllNBitUsers(SDNode *Node, unsigned Bits) const {
   assert((Node->getOpcode() == ISD::ADD || Node->getOpcode() == ISD::SUB ||
-          Node->getOpcode() == ISD::MUL || Node->getOpcode() == ISD::SHL) &&
+          Node->getOpcode() == ISD::MUL || Node->getOpcode() == ISD::SHL ||
+          isa<ConstantSDNode>(Node)) &&
          "Unexpected opcode");
 
   for (auto UI = Node->use_begin(), UE = Node->use_end(); UI != UE; ++UI) {
diff --git a/llvm/test/CodeGen/RISCV/calling-conv-half.ll b/llvm/test/CodeGen/RISCV/calling-conv-half.ll
--- a/llvm/test/CodeGen/RISCV/calling-conv-half.ll
+++ b/llvm/test/CodeGen/RISCV/calling-conv-half.ll
@@ -347,9 +347,8 @@
 ; RV64IF:       # %bb.0:
 ; RV64IF-NEXT:    addi sp, sp, -16
 ; RV64IF-NEXT:    sd ra, 8(sp) # 8-byte Folded Spill
-; RV64IF-NEXT:    addi a0, zero, -183
-; RV64IF-NEXT:    slli a0, a0, 40
-; RV64IF-NEXT:    srli t0, a0, 32
+; RV64IF-NEXT:    lui a0, 1048565
+; RV64IF-NEXT:    addiw t0, a0, -1792
 ; RV64IF-NEXT:    addi a0, zero, 1
 ; RV64IF-NEXT:    addi a1, zero, 2
 ; RV64IF-NEXT:    addi a2, zero, 3
diff --git a/llvm/test/CodeGen/RISCV/imm.ll b/llvm/test/CodeGen/RISCV/imm.ll
--- a/llvm/test/CodeGen/RISCV/imm.ll
+++ b/llvm/test/CodeGen/RISCV/imm.ll
@@ -482,15 +482,13 @@
 define void @imm_store_i16_neg1(i16* %p) nounwind {
 ; RV32I-LABEL: imm_store_i16_neg1:
 ; RV32I:       # %bb.0:
-; RV32I-NEXT:    lui a1, 16
-; RV32I-NEXT:    addi a1, a1, -1
+; RV32I-NEXT:    addi a1, zero, -1
 ; RV32I-NEXT:    sh a1, 0(a0)
 ; RV32I-NEXT:    ret
 ;
 ; RV64I-LABEL: imm_store_i16_neg1:
 ; RV64I:       # %bb.0:
-; RV64I-NEXT:    lui a1, 16
-; RV64I-NEXT:    addiw a1, a1, -1
+; RV64I-NEXT:    addi a1, zero, -1
 ; RV64I-NEXT:    sh a1, 0(a0)
 ; RV64I-NEXT:    ret
   store i16 -1, i16* %p
@@ -508,7 +506,6 @@
 ; RV64I-LABEL: imm_store_i32_neg1:
 ; RV64I:       # %bb.0:
 ; RV64I-NEXT:    addi a1, zero, -1
-; RV64I-NEXT:    srli a1, a1, 32
 ; RV64I-NEXT:    sw a1, 0(a0)
 ; RV64I-NEXT:    ret
   store i32 -1, i32* %p