diff --git a/llvm/lib/Target/RISCV/RISCVTargetTransformInfo.cpp b/llvm/lib/Target/RISCV/RISCVTargetTransformInfo.cpp
index 38304ff90252f..27a4d78d6df77 100644
--- a/llvm/lib/Target/RISCV/RISCVTargetTransformInfo.cpp
+++ b/llvm/lib/Target/RISCV/RISCVTargetTransformInfo.cpp
@@ -861,9 +861,14 @@ RISCVTTIImpl::getIntrinsicInstrCost(const IntrinsicCostAttributes &ICA,
   }
   // TODO: add more intrinsic
   case Intrinsic::experimental_stepvector: {
-    unsigned Cost = 1; // vid
     auto LT = getTypeLegalizationCost(RetTy);
-    return Cost + (LT.first - 1);
+    // Legalisation of illegal types involves an `index' instruction plus
+    // (LT.first - 1) vector adds.
+    if (ST->hasVInstructions())
+      return getRISCVInstructionCost(RISCV::VID_V, LT.second, CostKind) +
+             (LT.first - 1) *
+                 getRISCVInstructionCost(RISCV::VADD_VX, LT.second, CostKind);
+    return 1 + (LT.first - 1);
   }
   case Intrinsic::vp_rint: {
     // RISC-V target uses at least 5 instructions to lower rounding intrinsics.
diff --git a/llvm/test/Analysis/CostModel/RISCV/stepvector.ll b/llvm/test/Analysis/CostModel/RISCV/stepvector.ll
index 7d29d2c0cfa62..e59995572a108 100644
--- a/llvm/test/Analysis/CostModel/RISCV/stepvector.ll
+++ b/llvm/test/Analysis/CostModel/RISCV/stepvector.ll
@@ -4,98 +4,60 @@
 
 define void @stepvector() {
 ; CHECK-LABEL: 'stepvector'
-; CHECK-NEXT:  Cost Model: Found an estimated cost of 1 for instruction: %zero = call <vscale x 1 x i8> @llvm.experimental.stepvector.nxv1i8()
-; CHECK-NEXT:  Cost Model: Found an estimated cost of 1 for instruction: %1 = call <vscale x 2 x i8> @llvm.experimental.stepvector.nxv2i8()
-; CHECK-NEXT:  Cost Model: Found an estimated cost of 1 for instruction: %2 = call <vscale x 4 x i8> @llvm.experimental.stepvector.nxv4i8()
-; CHECK-NEXT:  Cost Model: Found an estimated cost of 1 for instruction: %3 = call <vscale x 8 x i8> @llvm.experimental.stepvector.nxv8i8()
+; CHECK-NEXT:  Cost Model: Found an estimated cost of 1 for instruction: %1 = call <vscale x 1 x i8> @llvm.experimental.stepvector.nxv1i8()
+; CHECK-NEXT:  Cost Model: Found an estimated cost of 1 for instruction: %2 = call <vscale x 2 x i8> @llvm.experimental.stepvector.nxv2i8()
+; CHECK-NEXT:  Cost Model: Found an estimated cost of 1 for instruction: %3 = call <vscale x 4 x i8> @llvm.experimental.stepvector.nxv4i8()
 ; CHECK-NEXT:  Cost Model: Found an estimated cost of 1 for instruction: %4 = call <vscale x 8 x i8> @llvm.experimental.stepvector.nxv8i8()
-; CHECK-NEXT:  Cost Model: Found an estimated cost of 1 for instruction: %5 = call <vscale x 8 x i8> @llvm.experimental.stepvector.nxv8i8()
-; CHECK-NEXT:  Cost Model: Found an estimated cost of 1 for instruction: %6 = call <vscale x 8 x i8> @llvm.experimental.stepvector.nxv8i8()
-; CHECK-NEXT:  Cost Model: Found an estimated cost of 1 for instruction: %7 = call <vscale x 8 x i8> @llvm.experimental.stepvector.nxv8i8()
-; CHECK-NEXT:  Cost Model: Found an estimated cost of 1 for instruction: %8 = call <vscale x 16 x i8> @llvm.experimental.stepvector.nxv16i8()
-; CHECK-NEXT:  Cost Model: Found an estimated cost of 1 for instruction: %9 = call <vscale x 32 x i8> @llvm.experimental.stepvector.nxv32i8()
-; CHECK-NEXT:  Cost Model: Found an estimated cost of 1 for instruction: %10 = call <vscale x 64 x i8> @llvm.experimental.stepvector.nxv64i8()
-; CHECK-NEXT:  Cost Model: Found an estimated cost of 1 for instruction: %11 = call <vscale x 1 x i16> @llvm.experimental.stepvector.nxv1i16()
-; CHECK-NEXT:  Cost Model: Found an estimated cost of 1 for instruction: %12 = call <vscale x 2 x i16> @llvm.experimental.stepvector.nxv2i16()
-; CHECK-NEXT:  Cost Model: Found an estimated cost of 1 for instruction: %13 = call <vscale x 4 x i16> @llvm.experimental.stepvector.nxv4i16()
-; CHECK-NEXT:  Cost Model: Found an estimated cost of 1 for instruction: %14 = call <vscale x 8 x i16> @llvm.experimental.stepvector.nxv8i16()
-; CHECK-NEXT:  Cost Model: Found an estimated cost of 1 for instruction: %15 = call <vscale x 16 x i16> @llvm.experimental.stepvector.nxv16i16()
-; CHECK-NEXT:  Cost Model: Found an estimated cost of 1 for instruction: %16 = call <vscale x 16 x i16> @llvm.experimental.stepvector.nxv16i16()
-; CHECK-NEXT:  Cost Model: Found an estimated cost of 1 for instruction: %17 = call <vscale x 16 x i16> @llvm.experimental.stepvector.nxv16i16()
-; CHECK-NEXT:  Cost Model: Found an estimated cost of 1 for instruction: %18 = call <vscale x 16 x i16> @llvm.experimental.stepvector.nxv16i16()
-; CHECK-NEXT:  Cost Model: Found an estimated cost of 1 for instruction: %19 = call <vscale x 16 x i16> @llvm.experimental.stepvector.nxv16i16()
-; CHECK-NEXT:  Cost Model: Found an estimated cost of 1 for instruction: %20 = call <vscale x 32 x i16> @llvm.experimental.stepvector.nxv32i16()
-; CHECK-NEXT:  Cost Model: Found an estimated cost of 1 for instruction: %21 = call <vscale x 1 x i32> @llvm.experimental.stepvector.nxv1i32()
-; CHECK-NEXT:  Cost Model: Found an estimated cost of 1 for instruction: %22 = call <vscale x 2 x i32> @llvm.experimental.stepvector.nxv2i32()
-; CHECK-NEXT:  Cost Model: Found an estimated cost of 1 for instruction: %23 = call <vscale x 4 x i32> @llvm.experimental.stepvector.nxv4i32()
-; CHECK-NEXT:  Cost Model: Found an estimated cost of 1 for instruction: %24 = call <vscale x 8 x i32> @llvm.experimental.stepvector.nxv8i32()
-; CHECK-NEXT:  Cost Model: Found an estimated cost of 1 for instruction: %25 = call <vscale x 16 x i32> @llvm.experimental.stepvector.nxv16i32()
-; CHECK-NEXT:  Cost Model: Found an estimated cost of 1 for instruction: %26 = call <vscale x 16 x i32> @llvm.experimental.stepvector.nxv16i32()
-; CHECK-NEXT:  Cost Model: Found an estimated cost of 1 for instruction: %27 = call <vscale x 16 x i32> @llvm.experimental.stepvector.nxv16i32()
-; CHECK-NEXT:  Cost Model: Found an estimated cost of 1 for instruction: %28 = call <vscale x 16 x i32> @llvm.experimental.stepvector.nxv16i32()
-; CHECK-NEXT:  Cost Model: Found an estimated cost of 1 for instruction: %29 = call <vscale x 16 x i32> @llvm.experimental.stepvector.nxv16i32()
-; CHECK-NEXT:  Cost Model: Found an estimated cost of 1 for instruction: %30 = call <vscale x 1 x i64> @llvm.experimental.stepvector.nxv1i64()
-; CHECK-NEXT:  Cost Model: Found an estimated cost of 1 for instruction: %31 = call <vscale x 2 x i64> @llvm.experimental.stepvector.nxv2i64()
-; CHECK-NEXT:  Cost Model: Found an estimated cost of 1 for instruction: %32 = call <vscale x 4 x i64> @llvm.experimental.stepvector.nxv4i64()
-; CHECK-NEXT:  Cost Model: Found an estimated cost of 1 for instruction: %33 = call <vscale x 8 x i64> @llvm.experimental.stepvector.nxv8i64()
-; CHECK-NEXT:  Cost Model: Found an estimated cost of 1 for instruction: %34 = call <vscale x 8 x i64> @llvm.experimental.stepvector.nxv8i64()
-; CHECK-NEXT:  Cost Model: Found an estimated cost of 1 for instruction: %35 = call <vscale x 8 x i64> @llvm.experimental.stepvector.nxv8i64()
-; CHECK-NEXT:  Cost Model: Found an estimated cost of 1 for instruction: %36 = call <vscale x 8 x i64> @llvm.experimental.stepvector.nxv8i64()
-; CHECK-NEXT:  Cost Model: Found an estimated cost of 1 for instruction: %37 = call <vscale x 8 x i64> @llvm.experimental.stepvector.nxv8i64()
-; CHECK-NEXT:  Cost Model: Found an estimated cost of 1 for instruction: %38 = call <vscale x 8 x i64> @llvm.experimental.stepvector.nxv8i64()
-; CHECK-NEXT:  Cost Model: Found an estimated cost of 2 for instruction: %39 = call <vscale x 16 x i64> @llvm.experimental.stepvector.nxv16i64()
-; CHECK-NEXT:  Cost Model: Found an estimated cost of 2 for instruction: %40 = call <vscale x 16 x i64> @llvm.experimental.stepvector.nxv16i64()
-; CHECK-NEXT:  Cost Model: Found an estimated cost of 2 for instruction: %41 = call <vscale x 16 x i64> @llvm.experimental.stepvector.nxv16i64()
-; CHECK-NEXT:  Cost Model: Found an estimated cost of 2 for instruction: %42 = call <vscale x 16 x i64> @llvm.experimental.stepvector.nxv16i64()
-; CHECK-NEXT:  Cost Model: Found an estimated cost of 2 for instruction: %43 = call <vscale x 16 x i64> @llvm.experimental.stepvector.nxv16i64()
-; CHECK-NEXT:  Cost Model: Found an estimated cost of 2 for instruction: %44 = call <vscale x 16 x i64> @llvm.experimental.stepvector.nxv16i64()
+; CHECK-NEXT:  Cost Model: Found an estimated cost of 2 for instruction: %5 = call <vscale x 16 x i8> @llvm.experimental.stepvector.nxv16i8()
+; CHECK-NEXT:  Cost Model: Found an estimated cost of 4 for instruction: %6 = call <vscale x 32 x i8> @llvm.experimental.stepvector.nxv32i8()
+; CHECK-NEXT:  Cost Model: Found an estimated cost of 8 for instruction: %7 = call <vscale x 64 x i8> @llvm.experimental.stepvector.nxv64i8()
+; CHECK-NEXT:  Cost Model: Found an estimated cost of 16 for instruction: %8 = call <vscale x 128 x i8> @llvm.experimental.stepvector.nxv128i8()
+; CHECK-NEXT:  Cost Model: Found an estimated cost of 1 for instruction: %9 = call <vscale x 1 x i16> @llvm.experimental.stepvector.nxv1i16()
+; CHECK-NEXT:  Cost Model: Found an estimated cost of 1 for instruction: %10 = call <vscale x 2 x i16> @llvm.experimental.stepvector.nxv2i16()
+; CHECK-NEXT:  Cost Model: Found an estimated cost of 1 for instruction: %11 = call <vscale x 4 x i16> @llvm.experimental.stepvector.nxv4i16()
+; CHECK-NEXT:  Cost Model: Found an estimated cost of 2 for instruction: %12 = call <vscale x 8 x i16> @llvm.experimental.stepvector.nxv8i16()
+; CHECK-NEXT:  Cost Model: Found an estimated cost of 4 for instruction: %13 = call <vscale x 16 x i16> @llvm.experimental.stepvector.nxv16i16()
+; CHECK-NEXT:  Cost Model: Found an estimated cost of 8 for instruction: %14 = call <vscale x 32 x i16> @llvm.experimental.stepvector.nxv32i16()
+; CHECK-NEXT:  Cost Model: Found an estimated cost of 16 for instruction: %15 = call <vscale x 64 x i16> @llvm.experimental.stepvector.nxv64i16()
+; CHECK-NEXT:  Cost Model: Found an estimated cost of 1 for instruction: %16 = call <vscale x 1 x i32> @llvm.experimental.stepvector.nxv1i32()
+; CHECK-NEXT:  Cost Model: Found an estimated cost of 1 for instruction: %17 = call <vscale x 2 x i32> @llvm.experimental.stepvector.nxv2i32()
+; CHECK-NEXT:  Cost Model: Found an estimated cost of 2 for instruction: %18 = call <vscale x 4 x i32> @llvm.experimental.stepvector.nxv4i32()
+; CHECK-NEXT:  Cost Model: Found an estimated cost of 4 for instruction: %19 = call <vscale x 8 x i32> @llvm.experimental.stepvector.nxv8i32()
+; CHECK-NEXT:  Cost Model: Found an estimated cost of 8 for instruction: %20 = call <vscale x 16 x i32> @llvm.experimental.stepvector.nxv16i32()
+; CHECK-NEXT:  Cost Model: Found an estimated cost of 16 for instruction: %21 = call <vscale x 32 x i32> @llvm.experimental.stepvector.nxv32i32()
+; CHECK-NEXT:  Cost Model: Found an estimated cost of 1 for instruction: %22 = call <vscale x 1 x i64> @llvm.experimental.stepvector.nxv1i64()
+; CHECK-NEXT:  Cost Model: Found an estimated cost of 2 for instruction: %23 = call <vscale x 2 x i64> @llvm.experimental.stepvector.nxv2i64()
+; CHECK-NEXT:  Cost Model: Found an estimated cost of 4 for instruction: %24 = call <vscale x 4 x i64> @llvm.experimental.stepvector.nxv4i64()
+; CHECK-NEXT:  Cost Model: Found an estimated cost of 8 for instruction: %25 = call <vscale x 8 x i64> @llvm.experimental.stepvector.nxv8i64()
+; CHECK-NEXT:  Cost Model: Found an estimated cost of 16 for instruction: %26 = call <vscale x 16 x i64> @llvm.experimental.stepvector.nxv16i64()
 ; CHECK-NEXT:  Cost Model: Found an estimated cost of 0 for instruction: ret void
 ;
-  %zero = call <vscale x 1 x i8> @llvm.experimental.stepvector.nxv1i8()
-  %1 = call <vscale x 2 x i8> @llvm.experimental.stepvector.nxv2i8()
-  %2 = call <vscale x 4 x i8> @llvm.experimental.stepvector.nxv4i8()
-  %3 = call <vscale x 8 x i8> @llvm.experimental.stepvector.nxv8i8()
-  %4 = call <vscale x 8 x i8> @llvm.experimental.stepvector.nxv8i8()
-  %5 = call <vscale x 8 x i8> @llvm.experimental.stepvector.nxv8i8()
-  %6 = call <vscale x 8 x i8> @llvm.experimental.stepvector.nxv8i8()
-  %7 = call <vscale x 8 x i8> @llvm.experimental.stepvector.nxv8i8()
-  %8 = call <vscale x 16 x i8> @llvm.experimental.stepvector.nxv16i8()
-  %9 = call <vscale x 32 x i8> @llvm.experimental.stepvector.nxv32i8()
-  %10 = call <vscale x 64 x i8> @llvm.experimental.stepvector.nxv64i8()
-  %11 = call <vscale x 1 x i16> @llvm.experimental.stepvector.nxv1i16()
-  %12 = call <vscale x 2 x i16> @llvm.experimental.stepvector.nxv2i16()
-  %13 = call <vscale x 4 x i16> @llvm.experimental.stepvector.nxv4i16()
-  %14 = call <vscale x 8 x i16> @llvm.experimental.stepvector.nxv8i16()
-  %15 = call <vscale x 16 x i16> @llvm.experimental.stepvector.nxv16i16()
-  %16 = call <vscale x 16 x i16> @llvm.experimental.stepvector.nxv16i16()
-  %17 = call <vscale x 16 x i16> @llvm.experimental.stepvector.nxv16i16()
-  %18 = call <vscale x 16 x i16> @llvm.experimental.stepvector.nxv16i16()
-  %19 = call <vscale x 16 x i16> @llvm.experimental.stepvector.nxv16i16()
-  %20 = call <vscale x 32 x i16> @llvm.experimental.stepvector.nxv32i16()
-  %21 = call <vscale x 1 x i32> @llvm.experimental.stepvector.nxv1i32()
-  %22 = call <vscale x 2 x i32> @llvm.experimental.stepvector.nxv2i32()
-  %23 = call <vscale x 4 x i32> @llvm.experimental.stepvector.nxv4i32()
-  %24 = call <vscale x 8 x i32> @llvm.experimental.stepvector.nxv8i32()
-  %25 = call <vscale x 16 x i32> @llvm.experimental.stepvector.nxv16i32()
-  %26 = call <vscale x 16 x i32> @llvm.experimental.stepvector.nxv16i32()
-  %27 = call <vscale x 16 x i32> @llvm.experimental.stepvector.nxv16i32()
-  %28 = call <vscale x 16 x i32> @llvm.experimental.stepvector.nxv16i32()
-  %29 = call <vscale x 16 x i32> @llvm.experimental.stepvector.nxv16i32()
-  %30 = call <vscale x 1 x i64> @llvm.experimental.stepvector.nxv1i64()
-  %31 = call <vscale x 2 x i64> @llvm.experimental.stepvector.nxv2i64()
-  %32 = call <vscale x 4 x i64> @llvm.experimental.stepvector.nxv4i64()
-  %33 = call <vscale x 8 x i64> @llvm.experimental.stepvector.nxv8i64()
-  %34 = call <vscale x 8 x i64> @llvm.experimental.stepvector.nxv8i64()
-  %35 = call <vscale x 8 x i64> @llvm.experimental.stepvector.nxv8i64()
-  %36 = call <vscale x 8 x i64> @llvm.experimental.stepvector.nxv8i64()
-  %37 = call <vscale x 8 x i64> @llvm.experimental.stepvector.nxv8i64()
-  %38 = call <vscale x 8 x i64> @llvm.experimental.stepvector.nxv8i64()
-  %39 = call <vscale x 16 x i64> @llvm.experimental.stepvector.nxv16i64()
-  %40 = call <vscale x 16 x i64> @llvm.experimental.stepvector.nxv16i64()
-  %41 = call <vscale x 16 x i64> @llvm.experimental.stepvector.nxv16i64()
-  %42 = call <vscale x 16 x i64> @llvm.experimental.stepvector.nxv16i64()
-  %43 = call <vscale x 16 x i64> @llvm.experimental.stepvector.nxv16i64()
-  %44 = call <vscale x 16 x i64> @llvm.experimental.stepvector.nxv16i64()
+  call <vscale x 1 x i8> @llvm.experimental.stepvector.nxv1i8()
+  call <vscale x 2 x i8> @llvm.experimental.stepvector.nxv2i8()
+  call <vscale x 4 x i8> @llvm.experimental.stepvector.nxv4i8()
+  call <vscale x 8 x i8> @llvm.experimental.stepvector.nxv8i8()
+  call <vscale x 16 x i8> @llvm.experimental.stepvector.nxv16i8()
+  call <vscale x 32 x i8> @llvm.experimental.stepvector.nxv32i8()
+  call <vscale x 64 x i8> @llvm.experimental.stepvector.nxv64i8()
+  call <vscale x 128 x i8> @llvm.experimental.stepvector.nxv128i8()
+  call <vscale x 1 x i16> @llvm.experimental.stepvector.nxv1i16()
+  call <vscale x 2 x i16> @llvm.experimental.stepvector.nxv2i16()
+  call <vscale x 4 x i16> @llvm.experimental.stepvector.nxv4i16()
+  call <vscale x 8 x i16> @llvm.experimental.stepvector.nxv8i16()
+  call <vscale x 16 x i16> @llvm.experimental.stepvector.nxv16i16()
+  call <vscale x 32 x i16> @llvm.experimental.stepvector.nxv32i16()
+  call <vscale x 64 x i16> @llvm.experimental.stepvector.nxv64i16()
+  call <vscale x 1 x i32> @llvm.experimental.stepvector.nxv1i32()
+  call <vscale x 2 x i32> @llvm.experimental.stepvector.nxv2i32()
+  call <vscale x 4 x i32> @llvm.experimental.stepvector.nxv4i32()
+  call <vscale x 8 x i32> @llvm.experimental.stepvector.nxv8i32()
+  call <vscale x 16 x i32> @llvm.experimental.stepvector.nxv16i32()
+  call <vscale x 32 x i32> @llvm.experimental.stepvector.nxv32i32()
+  call <vscale x 1 x i64> @llvm.experimental.stepvector.nxv1i64()
+  call <vscale x 2 x i64> @llvm.experimental.stepvector.nxv2i64()
+  call <vscale x 4 x i64> @llvm.experimental.stepvector.nxv4i64()
+  call <vscale x 8 x i64> @llvm.experimental.stepvector.nxv8i64()
+  call <vscale x 16 x i64> @llvm.experimental.stepvector.nxv16i64()
   ret void
 }
 
@@ -107,17 +69,20 @@ declare <vscale x 8 x i8> @llvm.experimental.stepvector.nxv8i8()
 declare <vscale x 16 x i8> @llvm.experimental.stepvector.nxv16i8()
 declare <vscale x 32 x i8> @llvm.experimental.stepvector.nxv32i8()
 declare <vscale x 64 x i8> @llvm.experimental.stepvector.nxv64i8()
+declare <vscale x 128 x i8> @llvm.experimental.stepvector.nxv128i8()
 declare <vscale x 1 x i16> @llvm.experimental.stepvector.nxv1i16()
 declare <vscale x 2 x i16> @llvm.experimental.stepvector.nxv2i16()
 declare <vscale x 4 x i16> @llvm.experimental.stepvector.nxv4i16()
 declare <vscale x 8 x i16> @llvm.experimental.stepvector.nxv8i16()
 declare <vscale x 16 x i16> @llvm.experimental.stepvector.nxv16i16()
 declare <vscale x 32 x i16> @llvm.experimental.stepvector.nxv32i16()
+declare <vscale x 64 x i16> @llvm.experimental.stepvector.nxv64i16()
 declare <vscale x 1 x i32> @llvm.experimental.stepvector.nxv1i32()
 declare <vscale x 2 x i32> @llvm.experimental.stepvector.nxv2i32()
 declare <vscale x 4 x i32> @llvm.experimental.stepvector.nxv4i32()
 declare <vscale x 8 x i32> @llvm.experimental.stepvector.nxv8i32()
 declare <vscale x 16 x i32> @llvm.experimental.stepvector.nxv16i32()
+declare <vscale x 32 x i32> @llvm.experimental.stepvector.nxv32i32()
 declare <vscale x 1 x i64> @llvm.experimental.stepvector.nxv1i64()
 declare <vscale x 2 x i64> @llvm.experimental.stepvector.nxv2i64()
 declare <vscale x 4 x i64> @llvm.experimental.stepvector.nxv4i64()