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
@@ -7712,6 +7712,24 @@
   MVT XLenVT = Subtarget.getXLenVT();
   SDValue VL = DAG.getRegister(RISCV::X0, XLenVT);
 
+  // If the VT is LMUL=8, we need to split and reassemble.
+  if (VecVT.getSizeInBits().getKnownMinValue() == (8 * RISCV::RVVBitsPerBlock)) {
+    auto [Op0Lo, Op0Hi] = DAG.SplitVectorOperand(Op.getNode(), 0);
+    auto [Op1Lo, Op1Hi] = DAG.SplitVectorOperand(Op.getNode(), 1);
+    EVT SplitVT = Op0Lo.getValueType();
+
+    SDValue ResLo = DAG.getNode(ISD::VECTOR_INTERLEAVE, DL,
+                                DAG.getVTList(SplitVT, SplitVT), Op0Lo, Op1Lo);
+    SDValue ResHi = DAG.getNode(ISD::VECTOR_INTERLEAVE, DL,
+                                DAG.getVTList(SplitVT, SplitVT), Op0Hi, Op1Hi);
+
+    SDValue Lo = DAG.getNode(ISD::CONCAT_VECTORS, DL, VecVT,
+                             ResLo.getValue(0), ResLo.getValue(1));
+    SDValue Hi = DAG.getNode(ISD::CONCAT_VECTORS, DL, VecVT,
+                             ResHi.getValue(0), ResHi.getValue(1));
+    return DAG.getMergeValues({Lo, Hi}, DL);
+  }
+
   SDValue Interleaved;
 
   // If the element type is smaller than ELEN, then we can interleave with
diff --git a/llvm/test/CodeGen/RISCV/rvv/vector-interleave.ll b/llvm/test/CodeGen/RISCV/rvv/vector-interleave.ll
--- a/llvm/test/CodeGen/RISCV/rvv/vector-interleave.ll
+++ b/llvm/test/CodeGen/RISCV/rvv/vector-interleave.ll
@@ -93,6 +93,137 @@
 declare <vscale x 8 x i32> @llvm.experimental.vector.interleave2.nxv8i32(<vscale x 4 x i32>, <vscale x 4 x i32>)
 declare <vscale x 4 x i64> @llvm.experimental.vector.interleave2.nxv4i64(<vscale x 2 x i64>, <vscale x 2 x i64>)
 
+define <vscale x 128 x i1> @vector_interleave_nxv128i1_nxv64i1(<vscale x 64 x i1> %a, <vscale x 64 x i1> %b) {
+; CHECK-LABEL: vector_interleave_nxv128i1_nxv64i1:
+; CHECK:       # %bb.0:
+; CHECK-NEXT:    vmv1r.v v9, v0
+; CHECK-NEXT:    vsetvli a0, zero, e8, m8, ta, ma
+; CHECK-NEXT:    vmv.v.i v24, 0
+; CHECK-NEXT:    vmv1r.v v0, v8
+; CHECK-NEXT:    vmerge.vim v16, v24, 1, v0
+; CHECK-NEXT:    vmv1r.v v0, v9
+; CHECK-NEXT:    vmerge.vim v8, v24, 1, v0
+; CHECK-NEXT:    vsetvli a0, zero, e8, m4, ta, ma
+; CHECK-NEXT:    vwaddu.vv v24, v8, v16
+; CHECK-NEXT:    li a0, -1
+; CHECK-NEXT:    vwmaccu.vx v24, a0, v16
+; CHECK-NEXT:    vsetvli a1, zero, e8, m8, ta, ma
+; CHECK-NEXT:    vmsne.vi v0, v24, 0
+; CHECK-NEXT:    vsetvli a1, zero, e8, m4, ta, ma
+; CHECK-NEXT:    vwaddu.vv v24, v12, v20
+; CHECK-NEXT:    vwmaccu.vx v24, a0, v20
+; CHECK-NEXT:    vsetvli a0, zero, e8, m8, ta, ma
+; CHECK-NEXT:    vmsne.vi v8, v24, 0
+; CHECK-NEXT:    ret
+  %res = call <vscale x 128 x i1> @llvm.experimental.vector.interleave2.nxv128i1(<vscale x 64 x i1> %a, <vscale x 64 x i1> %b)
+  ret <vscale x 128 x i1> %res
+}
+
+define <vscale x 128 x i8> @vector_interleave_nxv128i8_nxv64i8(<vscale x 64 x i8> %a, <vscale x 64 x i8> %b) {
+; CHECK-LABEL: vector_interleave_nxv128i8_nxv64i8:
+; CHECK:       # %bb.0:
+; CHECK-NEXT:    vmv8r.v v24, v8
+; CHECK-NEXT:    vsetvli a0, zero, e8, m4, ta, ma
+; CHECK-NEXT:    vwaddu.vv v8, v24, v16
+; CHECK-NEXT:    li a0, -1
+; CHECK-NEXT:    vwmaccu.vx v8, a0, v16
+; CHECK-NEXT:    vwaddu.vv v0, v28, v20
+; CHECK-NEXT:    vwmaccu.vx v0, a0, v20
+; CHECK-NEXT:    vmv8r.v v16, v0
+; CHECK-NEXT:    ret
+  %res = call <vscale x 128 x i8> @llvm.experimental.vector.interleave2.nxv128i8(<vscale x 64 x i8> %a, <vscale x 64 x i8> %b)
+  ret <vscale x 128 x i8> %res
+}
+
+define <vscale x 64 x i16> @vector_interleave_nxv64i16_nxv32i16(<vscale x 32 x i16> %a, <vscale x 32 x i16> %b) {
+; CHECK-LABEL: vector_interleave_nxv64i16_nxv32i16:
+; CHECK:       # %bb.0:
+; CHECK-NEXT:    vmv8r.v v24, v8
+; CHECK-NEXT:    vsetvli a0, zero, e16, m4, ta, ma
+; CHECK-NEXT:    vwaddu.vv v8, v24, v16
+; CHECK-NEXT:    li a0, -1
+; CHECK-NEXT:    vwmaccu.vx v8, a0, v16
+; CHECK-NEXT:    vwaddu.vv v0, v28, v20
+; CHECK-NEXT:    vwmaccu.vx v0, a0, v20
+; CHECK-NEXT:    vmv8r.v v16, v0
+; CHECK-NEXT:    ret
+  %res = call <vscale x 64 x i16> @llvm.experimental.vector.interleave2.nxv64i16(<vscale x 32 x i16> %a, <vscale x 32 x i16> %b)
+  ret <vscale x 64 x i16> %res
+}
+
+define <vscale x 32 x i32> @vector_interleave_nxv32i32_nxv16i32(<vscale x 16 x i32> %a, <vscale x 16 x i32> %b) {
+; CHECK-LABEL: vector_interleave_nxv32i32_nxv16i32:
+; CHECK:       # %bb.0:
+; CHECK-NEXT:    vmv8r.v v24, v8
+; CHECK-NEXT:    vsetvli a0, zero, e32, m4, ta, ma
+; CHECK-NEXT:    vwaddu.vv v8, v24, v16
+; CHECK-NEXT:    li a0, -1
+; CHECK-NEXT:    vwmaccu.vx v8, a0, v16
+; CHECK-NEXT:    vwaddu.vv v0, v28, v20
+; CHECK-NEXT:    vwmaccu.vx v0, a0, v20
+; CHECK-NEXT:    vmv8r.v v16, v0
+; CHECK-NEXT:    ret
+  %res = call <vscale x 32 x i32> @llvm.experimental.vector.interleave2.nxv32i32(<vscale x 16 x i32> %a, <vscale x 16 x i32> %b)
+  ret <vscale x 32 x i32> %res
+}
+
+define <vscale x 16 x i64> @vector_interleave_nxv16i64_nxv8i64(<vscale x 8 x i64> %a, <vscale x 8 x i64> %b) {
+; CHECK-LABEL: vector_interleave_nxv16i64_nxv8i64:
+; CHECK:       # %bb.0:
+; CHECK-NEXT:    addi sp, sp, -16
+; CHECK-NEXT:    .cfi_def_cfa_offset 16
+; CHECK-NEXT:    csrr a0, vlenb
+; CHECK-NEXT:    slli a0, a0, 4
+; CHECK-NEXT:    sub sp, sp, a0
+; CHECK-NEXT:    .cfi_escape 0x0f, 0x0d, 0x72, 0x00, 0x11, 0x10, 0x22, 0x11, 0x10, 0x92, 0xa2, 0x38, 0x00, 0x1e, 0x22 # sp + 16 + 16 * vlenb
+; CHECK-NEXT:    csrr a0, vlenb
+; CHECK-NEXT:    slli a0, a0, 3
+; CHECK-NEXT:    add a0, sp, a0
+; CHECK-NEXT:    addi a0, a0, 16
+; CHECK-NEXT:    vs8r.v v8, (a0) # Unknown-size Folded Spill
+; CHECK-NEXT:    csrr a0, vlenb
+; CHECK-NEXT:    srli a0, a0, 1
+; CHECK-NEXT:    vsetvli a1, zero, e16, m2, ta, mu
+; CHECK-NEXT:    vid.v v24
+; CHECK-NEXT:    vand.vi v26, v24, 1
+; CHECK-NEXT:    vmsne.vi v0, v26, 0
+; CHECK-NEXT:    vsrl.vi v2, v24, 1
+; CHECK-NEXT:    csrr a1, vlenb
+; CHECK-NEXT:    slli a1, a1, 3
+; CHECK-NEXT:    add a1, sp, a1
+; CHECK-NEXT:    addi a1, a1, 16
+; CHECK-NEXT:    vl8r.v v8, (a1) # Unknown-size Folded Reload
+; CHECK-NEXT:    vadd.vx v2, v2, a0, v0.t
+; CHECK-NEXT:    vmv4r.v v12, v16
+; CHECK-NEXT:    vsetvli zero, zero, e64, m8, ta, ma
+; CHECK-NEXT:    vrgatherei16.vv v24, v8, v2, v0.t
+; CHECK-NEXT:    addi a0, sp, 16
+; CHECK-NEXT:    vs8r.v v24, (a0) # Unknown-size Folded Spill
+; CHECK-NEXT:    csrr a0, vlenb
+; CHECK-NEXT:    slli a0, a0, 3
+; CHECK-NEXT:    add a0, sp, a0
+; CHECK-NEXT:    addi a0, a0, 16
+; CHECK-NEXT:    vl8r.v v8, (a0) # Unknown-size Folded Reload
+; CHECK-NEXT:    vmv4r.v v16, v12
+; CHECK-NEXT:    vrgatherei16.vv v24, v16, v2, v0.t
+; CHECK-NEXT:    addi a0, sp, 16
+; CHECK-NEXT:    vl8r.v v8, (a0) # Unknown-size Folded Reload
+; CHECK-NEXT:    vmv.v.v v16, v24
+; CHECK-NEXT:    csrr a0, vlenb
+; CHECK-NEXT:    slli a0, a0, 4
+; CHECK-NEXT:    add sp, sp, a0
+; CHECK-NEXT:    addi sp, sp, 16
+; CHECK-NEXT:    ret
+  %res = call <vscale x 16 x i64> @llvm.experimental.vector.interleave2.nxv16i64(<vscale x 8 x i64> %a, <vscale x 8 x i64> %b)
+  ret <vscale x 16 x i64> %res
+}
+
+declare <vscale x 128 x i1> @llvm.experimental.vector.interleave2.nxv128i1(<vscale x 64 x i1>, <vscale x 64 x i1>)
+declare <vscale x 128 x i8> @llvm.experimental.vector.interleave2.nxv128i8(<vscale x 64 x i8>, <vscale x 64 x i8>)
+declare <vscale x 64 x i16> @llvm.experimental.vector.interleave2.nxv64i16(<vscale x 32 x i16>, <vscale x 32 x i16>)
+declare <vscale x 32 x i32> @llvm.experimental.vector.interleave2.nxv32i32(<vscale x 16 x i32>, <vscale x 16 x i32>)
+declare <vscale x 16 x i64> @llvm.experimental.vector.interleave2.nxv16i64(<vscale x 8 x i64>, <vscale x 8 x i64>)
+
 ; Floats
 
 define <vscale x 4 x half> @vector_interleave_nxv4f16_nxv2f16(<vscale x 2 x half> %a, <vscale x 2 x half> %b) {
@@ -193,3 +324,90 @@
 declare <vscale x 16 x half> @llvm.experimental.vector.interleave2.nxv16f16(<vscale x 8 x half>, <vscale x 8 x half>)
 declare <vscale x 8 x float> @llvm.experimental.vector.interleave2.nxv8f32(<vscale x 4 x float>, <vscale x 4 x float>)
 declare <vscale x 4 x double> @llvm.experimental.vector.interleave2.nxv4f64(<vscale x 2 x double>, <vscale x 2 x double>)
+
+define <vscale x 64 x half> @vector_interleave_nxv64f16_nxv32f16(<vscale x 32 x half> %a, <vscale x 32 x half> %b) {
+; CHECK-LABEL: vector_interleave_nxv64f16_nxv32f16:
+; CHECK:       # %bb.0:
+; CHECK-NEXT:    vmv8r.v v24, v8
+; CHECK-NEXT:    vsetvli a0, zero, e16, m4, ta, ma
+; CHECK-NEXT:    vwaddu.vv v8, v24, v16
+; CHECK-NEXT:    li a0, -1
+; CHECK-NEXT:    vwmaccu.vx v8, a0, v16
+; CHECK-NEXT:    vwaddu.vv v0, v28, v20
+; CHECK-NEXT:    vwmaccu.vx v0, a0, v20
+; CHECK-NEXT:    vmv8r.v v16, v0
+; CHECK-NEXT:    ret
+  %res = call <vscale x 64 x half> @llvm.experimental.vector.interleave2.nxv64f16(<vscale x 32 x half> %a, <vscale x 32 x half> %b)
+  ret <vscale x 64 x half> %res
+}
+
+define <vscale x 32 x float> @vector_interleave_nxv32f32_nxv16f32(<vscale x 16 x float> %a, <vscale x 16 x float> %b) {
+; CHECK-LABEL: vector_interleave_nxv32f32_nxv16f32:
+; CHECK:       # %bb.0:
+; CHECK-NEXT:    vmv8r.v v24, v8
+; CHECK-NEXT:    vsetvli a0, zero, e32, m4, ta, ma
+; CHECK-NEXT:    vwaddu.vv v8, v24, v16
+; CHECK-NEXT:    li a0, -1
+; CHECK-NEXT:    vwmaccu.vx v8, a0, v16
+; CHECK-NEXT:    vwaddu.vv v0, v28, v20
+; CHECK-NEXT:    vwmaccu.vx v0, a0, v20
+; CHECK-NEXT:    vmv8r.v v16, v0
+; CHECK-NEXT:    ret
+  %res = call <vscale x 32 x float> @llvm.experimental.vector.interleave2.nxv32f32(<vscale x 16 x float> %a, <vscale x 16 x float> %b)
+  ret <vscale x 32 x float> %res
+}
+
+define <vscale x 16 x double> @vector_interleave_nxv16f64_nxv8f64(<vscale x 8 x double> %a, <vscale x 8 x double> %b) {
+; CHECK-LABEL: vector_interleave_nxv16f64_nxv8f64:
+; CHECK:       # %bb.0:
+; CHECK-NEXT:    addi sp, sp, -16
+; CHECK-NEXT:    .cfi_def_cfa_offset 16
+; CHECK-NEXT:    csrr a0, vlenb
+; CHECK-NEXT:    slli a0, a0, 4
+; CHECK-NEXT:    sub sp, sp, a0
+; CHECK-NEXT:    .cfi_escape 0x0f, 0x0d, 0x72, 0x00, 0x11, 0x10, 0x22, 0x11, 0x10, 0x92, 0xa2, 0x38, 0x00, 0x1e, 0x22 # sp + 16 + 16 * vlenb
+; CHECK-NEXT:    csrr a0, vlenb
+; CHECK-NEXT:    slli a0, a0, 3
+; CHECK-NEXT:    add a0, sp, a0
+; CHECK-NEXT:    addi a0, a0, 16
+; CHECK-NEXT:    vs8r.v v8, (a0) # Unknown-size Folded Spill
+; CHECK-NEXT:    csrr a0, vlenb
+; CHECK-NEXT:    srli a0, a0, 1
+; CHECK-NEXT:    vsetvli a1, zero, e16, m2, ta, mu
+; CHECK-NEXT:    vid.v v24
+; CHECK-NEXT:    vand.vi v26, v24, 1
+; CHECK-NEXT:    vmsne.vi v0, v26, 0
+; CHECK-NEXT:    vsrl.vi v2, v24, 1
+; CHECK-NEXT:    csrr a1, vlenb
+; CHECK-NEXT:    slli a1, a1, 3
+; CHECK-NEXT:    add a1, sp, a1
+; CHECK-NEXT:    addi a1, a1, 16
+; CHECK-NEXT:    vl8r.v v8, (a1) # Unknown-size Folded Reload
+; CHECK-NEXT:    vadd.vx v2, v2, a0, v0.t
+; CHECK-NEXT:    vmv4r.v v12, v16
+; CHECK-NEXT:    vsetvli zero, zero, e64, m8, ta, ma
+; CHECK-NEXT:    vrgatherei16.vv v24, v8, v2, v0.t
+; CHECK-NEXT:    addi a0, sp, 16
+; CHECK-NEXT:    vs8r.v v24, (a0) # Unknown-size Folded Spill
+; CHECK-NEXT:    csrr a0, vlenb
+; CHECK-NEXT:    slli a0, a0, 3
+; CHECK-NEXT:    add a0, sp, a0
+; CHECK-NEXT:    addi a0, a0, 16
+; CHECK-NEXT:    vl8r.v v8, (a0) # Unknown-size Folded Reload
+; CHECK-NEXT:    vmv4r.v v16, v12
+; CHECK-NEXT:    vrgatherei16.vv v24, v16, v2, v0.t
+; CHECK-NEXT:    addi a0, sp, 16
+; CHECK-NEXT:    vl8r.v v8, (a0) # Unknown-size Folded Reload
+; CHECK-NEXT:    vmv.v.v v16, v24
+; CHECK-NEXT:    csrr a0, vlenb
+; CHECK-NEXT:    slli a0, a0, 4
+; CHECK-NEXT:    add sp, sp, a0
+; CHECK-NEXT:    addi sp, sp, 16
+; CHECK-NEXT:    ret
+  %res = call <vscale x 16 x double> @llvm.experimental.vector.interleave2.nxv16f64(<vscale x 8 x double> %a, <vscale x 8 x double> %b)
+  ret <vscale x 16 x double> %res
+}
+
+declare <vscale x 64 x half> @llvm.experimental.vector.interleave2.nxv64f16(<vscale x 32 x half>, <vscale x 32 x half>)
+declare <vscale x 32 x float> @llvm.experimental.vector.interleave2.nxv32f32(<vscale x 16 x float>, <vscale x 16 x float>)
+declare <vscale x 16 x double> @llvm.experimental.vector.interleave2.nxv16f64(<vscale x 8 x double>, <vscale x 8 x double>)