diff --git a/llvm/lib/Target/RISCV/RISCVISelLowering.h b/llvm/lib/Target/RISCV/RISCVISelLowering.h
--- a/llvm/lib/Target/RISCV/RISCVISelLowering.h
+++ b/llvm/lib/Target/RISCV/RISCVISelLowering.h
@@ -243,6 +243,9 @@
                     bool ForCodeSize) const override;
 
   bool hasBitPreservingFPLogic(EVT VT) const override;
+  bool
+  shouldExpandBuildVectorWithShuffles(EVT VT,
+                                      unsigned DefinedValues) const override;
 
   // Provide custom lowering hooks for some operations.
   SDValue LowerOperation(SDValue Op, SelectionDAG &DAG) const override;
diff --git a/llvm/lib/Target/RISCV/RISCVISelLowering.cpp b/llvm/lib/Target/RISCV/RISCVISelLowering.cpp
--- a/llvm/lib/Target/RISCV/RISCVISelLowering.cpp
+++ b/llvm/lib/Target/RISCV/RISCVISelLowering.cpp
@@ -554,6 +554,7 @@
         }
 
         setOperationAction(ISD::VECTOR_SHUFFLE, VT, Custom);
+        setOperationAction(ISD::INSERT_VECTOR_ELT, VT, Custom);
         setOperationAction(ISD::EXTRACT_VECTOR_ELT, VT, Custom);
 
         setOperationAction(ISD::ADD, VT, Custom);
@@ -610,6 +611,7 @@
 
         setOperationAction(ISD::BUILD_VECTOR, VT, Custom);
         setOperationAction(ISD::VECTOR_SHUFFLE, VT, Custom);
+        setOperationAction(ISD::INSERT_VECTOR_ELT, VT, Custom);
         setOperationAction(ISD::EXTRACT_VECTOR_ELT, VT, Custom);
 
         setOperationAction(ISD::LOAD, VT, Custom);
@@ -1021,6 +1023,19 @@
   return getDefaultVLOps(VecVT, VecVT, DL, DAG, Subtarget);
 }
 
+// The state of RVV BUILD_VECTOR and VECTOR_SHUFFLE lowering is that very few
+// of either is (currently) supported. This can get us into an infinite loop
+// where we try to lower a BUILD_VECTOR as a VECTOR_SHUFFLE as a BUILD_VECTOR
+// as a ..., etc.
+// Until either (or both) of these can reliably lower any node, reporting that
+// we don't want to expand BUILD_VECTORs via VECTOR_SHUFFLEs at least breaks
+// the infinite loop. Note that this lowers BUILD_VECTOR through the stack,
+// which is not desirable.
+bool RISCVTargetLowering::shouldExpandBuildVectorWithShuffles(
+    EVT VT, unsigned DefinedValues) const {
+  return false;
+}
+
 static SDValue lowerBUILD_VECTOR(SDValue Op, SelectionDAG &DAG,
                                  const RISCVSubtarget &Subtarget) {
   MVT VT = Op.getSimpleValueType();
@@ -2179,6 +2194,16 @@
   SDValue Val = Op.getOperand(1);
   SDValue Idx = Op.getOperand(2);
 
+  MVT ContainerVT = VecVT;
+  // If the operand is a fixed-length vector, convert to a scalable one.
+  if (VecVT.isFixedLengthVector()) {
+    ContainerVT = getContainerForFixedLengthVector(DAG, VecVT, Subtarget);
+    Vec = convertToScalableVector(ContainerVT, Vec, DAG, Subtarget);
+  }
+
+  SDValue Mask, VL;
+  std::tie(Mask, VL) = getDefaultVLOps(VecVT, ContainerVT, DL, DAG, Subtarget);
+
   // Custom-legalize INSERT_VECTOR_ELT where XLEN>=SEW, so that the vector is
   // first slid down into position, the value is inserted into the first
   // position, and the vector is slid back up. We do this to simplify patterns.
@@ -2186,21 +2211,17 @@
   if (Subtarget.is64Bit() || Val.getValueType() != MVT::i64) {
     if (isNullConstant(Idx))
       return Op;
-    SDValue Mask, VL;
-    std::tie(Mask, VL) = getDefaultScalableVLOps(VecVT, DL, DAG, Subtarget);
-    SDValue Slidedown = DAG.getNode(RISCVISD::VSLIDEDOWN_VL, DL, VecVT,
-                                    DAG.getUNDEF(VecVT), Vec, Idx, Mask, VL);
+    SDValue Slidedown =
+        DAG.getNode(RISCVISD::VSLIDEDOWN_VL, DL, ContainerVT,
+                    DAG.getUNDEF(ContainerVT), Vec, Idx, Mask, VL);
     SDValue InsertElt0 =
-        DAG.getNode(ISD::INSERT_VECTOR_ELT, DL, VecVT, Slidedown, Val,
+        DAG.getNode(ISD::INSERT_VECTOR_ELT, DL, ContainerVT, Slidedown, Val,
                     DAG.getConstant(0, DL, Subtarget.getXLenVT()));
 
-    return DAG.getNode(RISCVISD::VSLIDEUP_VL, DL, VecVT, Vec, InsertElt0, Idx,
-                       Mask, VL);
+    return DAG.getNode(RISCVISD::VSLIDEUP_VL, DL, ContainerVT, Vec, InsertElt0,
+                       Idx, Mask, VL);
   }
 
-  if (!VecVT.isScalableVector())
-    return SDValue();
-
   // Custom-legalize INSERT_VECTOR_ELT where XLEN<SEW, as the SEW element type
   // is illegal (currently only vXi64 RV32).
   // Since there is no easy way of getting a single element into a vector when
@@ -2212,17 +2233,21 @@
   // This essentially merges the original vector with the inserted element by
   // using a mask whose only set bit is that corresponding to the insert
   // index.
-  SDValue SplattedVal = DAG.getSplatVector(VecVT, DL, Val);
-  SDValue SplattedIdx = DAG.getNode(RISCVISD::SPLAT_VECTOR_I64, DL, VecVT, Idx);
+  SDValue SplattedVal = DAG.getSplatVector(ContainerVT, DL, Val);
+  SDValue SplattedIdx =
+      DAG.getNode(RISCVISD::VMV_V_X_VL, DL, ContainerVT, Idx, VL);
 
-  SDValue Mask, VL;
-  std::tie(Mask, VL) = getDefaultScalableVLOps(VecVT, DL, DAG, Subtarget);
-  SDValue VID = DAG.getNode(RISCVISD::VID_VL, DL, VecVT, Mask, VL);
+  SDValue VID = DAG.getNode(RISCVISD::VID_VL, DL, ContainerVT, Mask, VL);
   auto SetCCVT =
-      getSetCCResultType(DAG.getDataLayout(), *DAG.getContext(), VecVT);
-  SDValue SelectCond = DAG.getSetCC(DL, SetCCVT, VID, SplattedIdx, ISD::SETEQ);
-
-  return DAG.getNode(ISD::VSELECT, DL, VecVT, SelectCond, SplattedVal, Vec);
+      getSetCCResultType(DAG.getDataLayout(), *DAG.getContext(), ContainerVT);
+  SDValue SelectCond =
+      DAG.getNode(RISCVISD::SETCC_VL, DL, SetCCVT, VID, SplattedIdx,
+                  DAG.getCondCode(ISD::SETEQ), Mask, VL);
+  SDValue Select = DAG.getNode(RISCVISD::VSELECT_VL, DL, ContainerVT,
+                               SelectCond, SplattedVal, Vec, VL);
+  if (!VecVT.isFixedLengthVector())
+    return Select;
+  return convertFromScalableVector(VecVT, Select, DAG, Subtarget);
 }
 
 // Custom-lower EXTRACT_VECTOR_ELT operations to slide the vector down, then
diff --git a/llvm/test/CodeGen/RISCV/rvv/fixed-vectors-insert.ll b/llvm/test/CodeGen/RISCV/rvv/fixed-vectors-insert.ll
--- a/llvm/test/CodeGen/RISCV/rvv/fixed-vectors-insert.ll
+++ b/llvm/test/CodeGen/RISCV/rvv/fixed-vectors-insert.ll
@@ -8,88 +8,34 @@
 define void @insertelt_v4i64(<4 x i64>* %x, i64 %y) {
 ; RV32-LABEL: insertelt_v4i64:
 ; RV32:       # %bb.0:
-; RV32-NEXT:    addi sp, sp, -128
-; RV32-NEXT:    .cfi_def_cfa_offset 128
-; RV32-NEXT:    sw ra, 124(sp) # 4-byte Folded Spill
-; RV32-NEXT:    sw s0, 120(sp) # 4-byte Folded Spill
-; RV32-NEXT:    .cfi_offset ra, -4
-; RV32-NEXT:    .cfi_offset s0, -8
-; RV32-NEXT:    addi s0, sp, 128
-; RV32-NEXT:    .cfi_def_cfa s0, 0
-; RV32-NEXT:    andi sp, sp, -32
-; RV32-NEXT:    sw a2, 32(sp)
-; RV32-NEXT:    sw a1, 64(sp)
-; RV32-NEXT:    vsetivli a1, 8, e32,m2,ta,mu
-; RV32-NEXT:    vle32.v v26, (a0)
-; RV32-NEXT:    vmv.x.s a1, v26
-; RV32-NEXT:    sw a1, 0(sp)
-; RV32-NEXT:    addi a1, sp, 32
-; RV32-NEXT:    vle32.v v28, (a1)
-; RV32-NEXT:    vmv.x.s a1, v28
-; RV32-NEXT:    sw a1, 28(sp)
-; RV32-NEXT:    addi a1, sp, 64
-; RV32-NEXT:    vle32.v v28, (a1)
-; RV32-NEXT:    vmv.x.s a1, v28
-; RV32-NEXT:    sw a1, 24(sp)
-; RV32-NEXT:    vsetivli a1, 1, e32,m2,ta,mu
-; RV32-NEXT:    vslidedown.vi v28, v26, 5
-; RV32-NEXT:    vmv.x.s a1, v28
-; RV32-NEXT:    sw a1, 20(sp)
-; RV32-NEXT:    vslidedown.vi v28, v26, 4
-; RV32-NEXT:    vmv.x.s a1, v28
-; RV32-NEXT:    sw a1, 16(sp)
-; RV32-NEXT:    vslidedown.vi v28, v26, 3
-; RV32-NEXT:    vmv.x.s a1, v28
-; RV32-NEXT:    sw a1, 12(sp)
-; RV32-NEXT:    vslidedown.vi v28, v26, 2
-; RV32-NEXT:    vmv.x.s a1, v28
-; RV32-NEXT:    sw a1, 8(sp)
-; RV32-NEXT:    vslidedown.vi v26, v26, 1
-; RV32-NEXT:    vmv.x.s a1, v26
-; RV32-NEXT:    sw a1, 4(sp)
-; RV32-NEXT:    vsetivli a1, 8, e32,m2,ta,mu
-; RV32-NEXT:    vle32.v v26, (sp)
-; RV32-NEXT:    vse32.v v26, (a0)
-; RV32-NEXT:    addi sp, s0, -128
-; RV32-NEXT:    lw s0, 120(sp) # 4-byte Folded Reload
-; RV32-NEXT:    lw ra, 124(sp) # 4-byte Folded Reload
-; RV32-NEXT:    addi sp, sp, 128
+; RV32-NEXT:    vsetivli a3, 4, e64,m2,ta,mu
+; RV32-NEXT:    vle64.v v26, (a0)
+; RV32-NEXT:    vsetvli a3, zero, e64,m2,ta,mu
+; RV32-NEXT:    vmv.v.x v28, a2
+; RV32-NEXT:    addi a2, zero, 32
+; RV32-NEXT:    vsll.vx v28, v28, a2
+; RV32-NEXT:    vmv.v.x v30, a1
+; RV32-NEXT:    vsll.vx v30, v30, a2
+; RV32-NEXT:    vsrl.vx v30, v30, a2
+; RV32-NEXT:    vor.vv v28, v30, v28
+; RV32-NEXT:    vsetivli a1, 4, e64,m2,ta,mu
+; RV32-NEXT:    vid.v v30
+; RV32-NEXT:    vmseq.vi v0, v30, 3
+; RV32-NEXT:    vmerge.vvm v26, v26, v28, v0
+; RV32-NEXT:    vse64.v v26, (a0)
 ; RV32-NEXT:    ret
 ;
 ; RV64-LABEL: insertelt_v4i64:
 ; RV64:       # %bb.0:
-; RV64-NEXT:    addi sp, sp, -96
-; RV64-NEXT:    .cfi_def_cfa_offset 96
-; RV64-NEXT:    sd ra, 88(sp) # 8-byte Folded Spill
-; RV64-NEXT:    sd s0, 80(sp) # 8-byte Folded Spill
-; RV64-NEXT:    .cfi_offset ra, -8
-; RV64-NEXT:    .cfi_offset s0, -16
-; RV64-NEXT:    addi s0, sp, 96
-; RV64-NEXT:    .cfi_def_cfa s0, 0
-; RV64-NEXT:    andi sp, sp, -32
 ; RV64-NEXT:    vsetivli a2, 4, e64,m2,ta,mu
 ; RV64-NEXT:    vle64.v v26, (a0)
-; RV64-NEXT:    sd a1, 32(sp)
-; RV64-NEXT:    vmv.x.s a1, v26
-; RV64-NEXT:    sd a1, 0(sp)
-; RV64-NEXT:    addi a1, sp, 32
-; RV64-NEXT:    vle64.v v28, (a1)
-; RV64-NEXT:    vmv.x.s a1, v28
-; RV64-NEXT:    sd a1, 24(sp)
-; RV64-NEXT:    vsetivli a1, 1, e64,m2,ta,mu
-; RV64-NEXT:    vslidedown.vi v28, v26, 2
-; RV64-NEXT:    vmv.x.s a1, v28
-; RV64-NEXT:    sd a1, 16(sp)
-; RV64-NEXT:    vslidedown.vi v26, v26, 1
-; RV64-NEXT:    vmv.x.s a1, v26
-; RV64-NEXT:    sd a1, 8(sp)
+; RV64-NEXT:    vslidedown.vi v28, v26, 3
+; RV64-NEXT:    vsetvli a2, zero, e64,m2,ta,mu
+; RV64-NEXT:    vmv.s.x v28, a1
+; RV64-NEXT:    vsetivli a1, 4, e64,m2,tu,mu
+; RV64-NEXT:    vslideup.vi v26, v28, 3
 ; RV64-NEXT:    vsetivli a1, 4, e64,m2,ta,mu
-; RV64-NEXT:    vle64.v v26, (sp)
 ; RV64-NEXT:    vse64.v v26, (a0)
-; RV64-NEXT:    addi sp, s0, -96
-; RV64-NEXT:    ld s0, 80(sp) # 8-byte Folded Reload
-; RV64-NEXT:    ld ra, 88(sp) # 8-byte Folded Reload
-; RV64-NEXT:    addi sp, sp, 96
 ; RV64-NEXT:    ret
   %a = load <4 x i64>, <4 x i64>* %x
   %b = insertelement <4 x i64> %a, i64 %y, i32 3
@@ -104,8 +50,39 @@
 define void @insertelt_v3i64(<3 x i64>* %x, i64 %y) {
 ; RV32-LABEL: insertelt_v3i64:
 ; RV32:       # %bb.0:
+; RV32-NEXT:    addi sp, sp, -16
+; RV32-NEXT:    .cfi_def_cfa_offset 16
+; RV32-NEXT:    addi a3, a0, 16
+; RV32-NEXT:    vsetivli a4, 2, e32,m1,ta,mu
+; RV32-NEXT:    vle32.v v25, (a3)
+; RV32-NEXT:    vse32.v v25, (sp)
+; RV32-NEXT:    vsetivli a3, 2, e64,m1,ta,mu
+; RV32-NEXT:    vle64.v v26, (a0)
+; RV32-NEXT:    vsetivli a3, 8, e32,m2,ta,mu
+; RV32-NEXT:    vmv.v.i v28, 0
+; RV32-NEXT:    vsetivli a3, 2, e64,m2,tu,mu
+; RV32-NEXT:    vslideup.vi v28, v26, 0
+; RV32-NEXT:    vsetivli a3, 4, e32,m1,ta,mu
+; RV32-NEXT:    vle32.v v26, (sp)
+; RV32-NEXT:    vsetivli a3, 4, e64,m2,tu,mu
+; RV32-NEXT:    vslideup.vi v28, v26, 2
+; RV32-NEXT:    vsetvli a3, zero, e64,m2,ta,mu
+; RV32-NEXT:    vmv.v.x v26, a2
+; RV32-NEXT:    addi a3, zero, 32
+; RV32-NEXT:    vsll.vx v26, v26, a3
+; RV32-NEXT:    vmv.v.x v30, a1
+; RV32-NEXT:    vsll.vx v30, v30, a3
+; RV32-NEXT:    vsrl.vx v30, v30, a3
+; RV32-NEXT:    vor.vv v26, v30, v26
+; RV32-NEXT:    vsetivli a3, 4, e64,m2,ta,mu
+; RV32-NEXT:    vid.v v30
+; RV32-NEXT:    vmseq.vi v0, v30, 2
+; RV32-NEXT:    vmerge.vvm v26, v28, v26, v0
+; RV32-NEXT:    vsetivli a3, 2, e64,m1,ta,mu
+; RV32-NEXT:    vse64.v v26, (a0)
 ; RV32-NEXT:    sw a1, 16(a0)
 ; RV32-NEXT:    sw a2, 20(a0)
+; RV32-NEXT:    addi sp, sp, 16
 ; RV32-NEXT:    ret
 ;
 ; RV64-LABEL: insertelt_v3i64:
@@ -117,3 +94,103 @@
   store <3 x i64> %b, <3 x i64>* %x
   ret void
 }
+
+define void @insertelt_v16i8(<16 x i8>* %x, i8 %y) {
+; RV32-LABEL: insertelt_v16i8:
+; RV32:       # %bb.0:
+; RV32-NEXT:    vsetivli a2, 16, e8,m1,ta,mu
+; RV32-NEXT:    vle8.v v25, (a0)
+; RV32-NEXT:    vslidedown.vi v26, v25, 14
+; RV32-NEXT:    vsetvli a2, zero, e8,m1,ta,mu
+; RV32-NEXT:    vmv.s.x v26, a1
+; RV32-NEXT:    vsetivli a1, 16, e8,m1,tu,mu
+; RV32-NEXT:    vslideup.vi v25, v26, 14
+; RV32-NEXT:    vsetivli a1, 16, e8,m1,ta,mu
+; RV32-NEXT:    vse8.v v25, (a0)
+; RV32-NEXT:    ret
+;
+; RV64-LABEL: insertelt_v16i8:
+; RV64:       # %bb.0:
+; RV64-NEXT:    vsetivli a2, 16, e8,m1,ta,mu
+; RV64-NEXT:    vle8.v v25, (a0)
+; RV64-NEXT:    vslidedown.vi v26, v25, 14
+; RV64-NEXT:    vsetvli a2, zero, e8,m1,ta,mu
+; RV64-NEXT:    vmv.s.x v26, a1
+; RV64-NEXT:    vsetivli a1, 16, e8,m1,tu,mu
+; RV64-NEXT:    vslideup.vi v25, v26, 14
+; RV64-NEXT:    vsetivli a1, 16, e8,m1,ta,mu
+; RV64-NEXT:    vse8.v v25, (a0)
+; RV64-NEXT:    ret
+  %a = load <16 x i8>, <16 x i8>* %x
+  %b = insertelement <16 x i8> %a, i8 %y, i32 14
+  store <16 x i8> %b, <16 x i8>* %x
+  ret void
+}
+
+define void @insertelt_v32i16(<32 x i16>* %x, i16 %y, i32 %idx) {
+; RV32-LABEL: insertelt_v32i16:
+; RV32:       # %bb.0:
+; RV32-NEXT:    addi a3, zero, 32
+; RV32-NEXT:    vsetvli a4, a3, e16,m4,ta,mu
+; RV32-NEXT:    vle16.v v28, (a0)
+; RV32-NEXT:    vslidedown.vx v8, v28, a2
+; RV32-NEXT:    vsetvli a4, zero, e16,m4,ta,mu
+; RV32-NEXT:    vmv.s.x v8, a1
+; RV32-NEXT:    vsetvli a1, a3, e16,m4,tu,mu
+; RV32-NEXT:    vslideup.vx v28, v8, a2
+; RV32-NEXT:    vsetvli a1, a3, e16,m4,ta,mu
+; RV32-NEXT:    vse16.v v28, (a0)
+; RV32-NEXT:    ret
+;
+; RV64-LABEL: insertelt_v32i16:
+; RV64:       # %bb.0:
+; RV64-NEXT:    addi a3, zero, 32
+; RV64-NEXT:    vsetvli a4, a3, e16,m4,ta,mu
+; RV64-NEXT:    vle16.v v28, (a0)
+; RV64-NEXT:    sext.w a2, a2
+; RV64-NEXT:    vslidedown.vx v8, v28, a2
+; RV64-NEXT:    vsetvli a4, zero, e16,m4,ta,mu
+; RV64-NEXT:    vmv.s.x v8, a1
+; RV64-NEXT:    vsetvli a1, a3, e16,m4,tu,mu
+; RV64-NEXT:    vslideup.vx v28, v8, a2
+; RV64-NEXT:    vsetvli a1, a3, e16,m4,ta,mu
+; RV64-NEXT:    vse16.v v28, (a0)
+; RV64-NEXT:    ret
+  %a = load <32 x i16>, <32 x i16>* %x
+  %b = insertelement <32 x i16> %a, i16 %y, i32 %idx
+  store <32 x i16> %b, <32 x i16>* %x
+  ret void
+}
+
+define void @insertelt_v8f32(<8 x float>* %x, float %y, i32 %idx) {
+; RV32-LABEL: insertelt_v8f32:
+; RV32:       # %bb.0:
+; RV32-NEXT:    vsetivli a2, 8, e32,m2,ta,mu
+; RV32-NEXT:    vle32.v v26, (a0)
+; RV32-NEXT:    vslidedown.vx v28, v26, a1
+; RV32-NEXT:    vsetvli a2, zero, e32,m2,ta,mu
+; RV32-NEXT:    vfmv.s.f v28, fa0
+; RV32-NEXT:    vsetivli a2, 8, e32,m2,tu,mu
+; RV32-NEXT:    vslideup.vx v26, v28, a1
+; RV32-NEXT:    vsetivli a1, 8, e32,m2,ta,mu
+; RV32-NEXT:    vse32.v v26, (a0)
+; RV32-NEXT:    ret
+;
+; RV64-LABEL: insertelt_v8f32:
+; RV64:       # %bb.0:
+; RV64-NEXT:    vsetivli a2, 8, e32,m2,ta,mu
+; RV64-NEXT:    vle32.v v26, (a0)
+; RV64-NEXT:    sext.w a1, a1
+; RV64-NEXT:    vslidedown.vx v28, v26, a1
+; RV64-NEXT:    vsetvli a2, zero, e32,m2,ta,mu
+; RV64-NEXT:    vfmv.s.f v28, fa0
+; RV64-NEXT:    vsetivli a2, 8, e32,m2,tu,mu
+; RV64-NEXT:    vslideup.vx v26, v28, a1
+; RV64-NEXT:    vsetivli a1, 8, e32,m2,ta,mu
+; RV64-NEXT:    vse32.v v26, (a0)
+; RV64-NEXT:    ret
+  %a = load <8 x float>, <8 x float>* %x
+  %b = insertelement <8 x float> %a, float %y, i32 %idx
+  store <8 x float> %b, <8 x float>* %x
+  ret void
+}