diff --git a/llvm/lib/CodeGen/SelectionDAG/TargetLowering.cpp b/llvm/lib/CodeGen/SelectionDAG/TargetLowering.cpp
--- a/llvm/lib/CodeGen/SelectionDAG/TargetLowering.cpp
+++ b/llvm/lib/CodeGen/SelectionDAG/TargetLowering.cpp
@@ -1164,6 +1164,20 @@
     Known = KnownScl.trunc(BitWidth);
     break;
   }
+  case ISD::SPLAT_VECTOR_PARTS: {
+    unsigned NumSclBits = Op.getOperand(0).getScalarValueSizeInBits();
+    assert(NumSclBits * Op.getNumOperands() == BitWidth &&
+           "Expected SPLAT_VECTOR_PARTS scalars to cover element width");
+    for (auto [I, Scl] : enumerate(Op->ops())) {
+      APInt DemandedSclBits =
+          DemandedBits.extractBits(NumSclBits, NumSclBits * I);
+      KnownBits KnownScl;
+      if (SimplifyDemandedBits(Scl, DemandedSclBits, KnownScl, TLO, Depth + 1))
+        return true;
+      Known.insertBits(KnownScl, NumSclBits * I);
+    }
+    break;
+  }
   case ISD::LOAD: {
     auto *LD = cast<LoadSDNode>(Op);
     if (getTargetConstantFromLoad(LD)) {
diff --git a/llvm/test/CodeGen/RISCV/rvv/splat-vector-split-i64-vl-sdnode.ll b/llvm/test/CodeGen/RISCV/rvv/splat-vector-split-i64-vl-sdnode.ll
--- a/llvm/test/CodeGen/RISCV/rvv/splat-vector-split-i64-vl-sdnode.ll
+++ b/llvm/test/CodeGen/RISCV/rvv/splat-vector-split-i64-vl-sdnode.ll
@@ -93,17 +93,13 @@
 ; CHECK:       # %bb.0:
 ; CHECK-NEXT:    addi sp, sp, -16
 ; CHECK-NEXT:    .cfi_def_cfa_offset 16
-; CHECK-NEXT:    sw a1, 4(sp)
-; CHECK-NEXT:    sw a0, 0(sp)
-; CHECK-NEXT:    mv a0, sp
-; CHECK-NEXT:    vsetvli a1, zero, e64, m2, ta, ma
-; CHECK-NEXT:    vlse64.v v8, (a0), zero
 ; CHECK-NEXT:    sw zero, 12(sp)
-; CHECK-NEXT:    li a0, -1
-; CHECK-NEXT:    sw a0, 8(sp)
-; CHECK-NEXT:    addi a0, sp, 8
-; CHECK-NEXT:    vlse64.v v10, (a0), zero
-; CHECK-NEXT:    vand.vv v8, v8, v10
+; CHECK-NEXT:    li a1, -1
+; CHECK-NEXT:    sw a1, 8(sp)
+; CHECK-NEXT:    addi a1, sp, 8
+; CHECK-NEXT:    vsetvli a2, zero, e64, m2, ta, ma
+; CHECK-NEXT:    vlse64.v v8, (a1), zero
+; CHECK-NEXT:    vand.vx v8, v8, a0
 ; CHECK-NEXT:    addi sp, sp, 16
 ; CHECK-NEXT:    ret
   %1 = insertelement <vscale x 2 x i64> poison, i64 %x, i32 0