diff --git a/llvm/lib/Target/AArch64/AArch64ISelLowering.cpp b/llvm/lib/Target/AArch64/AArch64ISelLowering.cpp
--- a/llvm/lib/Target/AArch64/AArch64ISelLowering.cpp
+++ b/llvm/lib/Target/AArch64/AArch64ISelLowering.cpp
@@ -19105,6 +19105,12 @@
   SDValue Chain = ST->getChain();
   SDValue Value = ST->getValue();
   SDValue Ptr = ST->getBasePtr();
+  EVT ValueVT = Value.getValueType();
+
+  auto hasValidElementTypeForFPTruncStore = [](EVT VT) {
+    EVT EltVT = VT.getVectorElementType();
+    return EltVT == MVT::f32 || EltVT == MVT::f64;
+  };
 
   // If this is an FP_ROUND followed by a store, fold this into a truncating
   // store. We can do this even if this is already a truncstore.
@@ -19113,9 +19119,9 @@
   if (DCI.isBeforeLegalizeOps() && Value.getOpcode() == ISD::FP_ROUND &&
       Value.getNode()->hasOneUse() && ST->isUnindexed() &&
       Subtarget->useSVEForFixedLengthVectors() &&
-      Value.getValueType().isFixedLengthVector() &&
-      Value.getValueType().getFixedSizeInBits() >=
-          Subtarget->getMinSVEVectorSizeInBits())
+      ValueVT.isFixedLengthVector() &&
+      ValueVT.getFixedSizeInBits() >= Subtarget->getMinSVEVectorSizeInBits() &&
+      hasValidElementTypeForFPTruncStore(Value.getOperand(0).getValueType()))
     return DAG.getTruncStore(Chain, SDLoc(N), Value.getOperand(0), Ptr,
                              ST->getMemoryVT(), ST->getMemOperand());
 
@@ -21021,12 +21027,17 @@
   if (N->hasOneUse() && N->use_begin()->getOpcode() == ISD::FP_ROUND)
     return SDValue();
 
+  auto hasValidElementTypeForFPExtLoad = [](EVT VT) {
+    EVT EltVT = VT.getVectorElementType();
+    return EltVT == MVT::f32 || EltVT == MVT::f64;
+  };
+
   // fold (fpext (load x)) -> (fpext (fptrunc (extload x)))
   // We purposefully don't care about legality of the nodes here as we know
   // they can be split down into something legal.
   if (DCI.isBeforeLegalizeOps() && ISD::isNormalLoad(N0.getNode()) &&
       N0.hasOneUse() && Subtarget->useSVEForFixedLengthVectors() &&
-      VT.isFixedLengthVector() &&
+      VT.isFixedLengthVector() && hasValidElementTypeForFPExtLoad(VT) &&
       VT.getFixedSizeInBits() >= Subtarget->getMinSVEVectorSizeInBits()) {
     LoadSDNode *LN0 = cast<LoadSDNode>(N0);
     SDValue ExtLoad = DAG.getExtLoad(ISD::EXTLOAD, SDLoc(N), VT,
diff --git a/llvm/test/CodeGen/AArch64/sve-fixed-length-fp128.ll b/llvm/test/CodeGen/AArch64/sve-fixed-length-fp128.ll
new file mode 100644
--- /dev/null
+++ b/llvm/test/CodeGen/AArch64/sve-fixed-length-fp128.ll
@@ -0,0 +1,138 @@
+; NOTE: Assertions have been autogenerated by utils/update_llc_test_checks.py
+; RUN: llc < %s | FileCheck %s
+
+target triple = "aarch64-unknown-linux-gnu"
+
+; Ensure we don't attempt to combine into an extending fp128 load.
+define void @fcvt_v4f64_v4f128(ptr %a, ptr %b) vscale_range(2,0) #0 {
+; CHECK-LABEL: fcvt_v4f64_v4f128:
+; CHECK:       // %bb.0:
+; CHECK-NEXT:    str x29, [sp, #-32]! // 8-byte Folded Spill
+; CHECK-NEXT:    stp x30, x19, [sp, #16] // 16-byte Folded Spill
+; CHECK-NEXT:    addvl sp, sp, #-2
+; CHECK-NEXT:    sub sp, sp, #48
+; CHECK-NEXT:    ptrue p0.d, vl4
+; CHECK-NEXT:    add x8, sp, #48
+; CHECK-NEXT:    ld1d { z0.d }, p0/z, [x0]
+; CHECK-NEXT:    mov x19, x1
+; CHECK-NEXT:    str z0, [x8, #1, mul vl] // 16-byte Folded Spill
+; CHECK-NEXT:    ext z0.b, z0.b, z0.b, #16
+; CHECK-NEXT:    str z0, [x8] // 16-byte Folded Spill
+; CHECK-NEXT:    // kill: def $d0 killed $d0 killed $z0
+; CHECK-NEXT:    bl __extenddftf2
+; CHECK-NEXT:    add x8, sp, #48
+; CHECK-NEXT:    ldr z1, [x8] // 16-byte Folded Reload
+; CHECK-NEXT:    str q0, [sp, #32] // 16-byte Folded Spill
+; CHECK-NEXT:    mov d1, v1.d[1]
+; CHECK-NEXT:    fmov d0, d1
+; CHECK-NEXT:    bl __extenddftf2
+; CHECK-NEXT:    add x8, sp, #48
+; CHECK-NEXT:    str q0, [sp, #16] // 16-byte Folded Spill
+; CHECK-NEXT:    ldr z0, [x8, #1, mul vl] // 16-byte Folded Reload
+; CHECK-NEXT:    // kill: def $d0 killed $d0 killed $z0
+; CHECK-NEXT:    bl __extenddftf2
+; CHECK-NEXT:    add x8, sp, #48
+; CHECK-NEXT:    ldr z1, [x8, #1, mul vl] // 16-byte Folded Reload
+; CHECK-NEXT:    str q0, [sp] // 16-byte Folded Spill
+; CHECK-NEXT:    mov d1, v1.d[1]
+; CHECK-NEXT:    fmov d0, d1
+; CHECK-NEXT:    bl __extenddftf2
+; CHECK-NEXT:    ldr q1, [sp] // 16-byte Folded Reload
+; CHECK-NEXT:    ldr q2, [sp, #16] // 16-byte Folded Reload
+; CHECK-NEXT:    stp q1, q0, [x19]
+; CHECK-NEXT:    ldr q0, [sp, #32] // 16-byte Folded Reload
+; CHECK-NEXT:    stp q0, q2, [x19, #32]
+; CHECK-NEXT:    addvl sp, sp, #2
+; CHECK-NEXT:    add sp, sp, #48
+; CHECK-NEXT:    ldp x30, x19, [sp, #16] // 16-byte Folded Reload
+; CHECK-NEXT:    ldr x29, [sp], #32 // 8-byte Folded Reload
+; CHECK-NEXT:    ret
+  %op1 = load <4 x double>, ptr %a
+  %res = fpext <4 x double> %op1 to <4 x fp128>
+  store <4 x fp128> %res, ptr %b
+  ret void
+}
+
+; Ensure we don't attempt to combine into a truncateing fp128 store.
+define void @fcvt_v4f128_v4f64(ptr %a, ptr %b) vscale_range(2,0) #0 {
+; CHECK-LABEL: fcvt_v4f128_v4f64:
+; CHECK:       // %bb.0:
+; CHECK-NEXT:    str x29, [sp, #-32]! // 8-byte Folded Spill
+; CHECK-NEXT:    stp x30, x19, [sp, #16] // 16-byte Folded Spill
+; CHECK-NEXT:    addvl sp, sp, #-2
+; CHECK-NEXT:    sub sp, sp, #128
+; CHECK-NEXT:    ldr q1, [x0, #64]
+; CHECK-NEXT:    mov x19, x1
+; CHECK-NEXT:    ldr q0, [x0, #80]
+; CHECK-NEXT:    stp q0, q1, [sp, #96] // 32-byte Folded Spill
+; CHECK-NEXT:    ldr q1, [x0, #96]
+; CHECK-NEXT:    ldr q0, [x0, #112]
+; CHECK-NEXT:    stp q0, q1, [sp, #64] // 32-byte Folded Spill
+; CHECK-NEXT:    ldr q1, [x0]
+; CHECK-NEXT:    ldr q0, [x0, #16]
+; CHECK-NEXT:    stp q0, q1, [sp, #32] // 32-byte Folded Spill
+; CHECK-NEXT:    ldr q0, [x0, #32]
+; CHECK-NEXT:    str q0, [sp, #16] // 16-byte Folded Spill
+; CHECK-NEXT:    ldr q0, [x0, #48]
+; CHECK-NEXT:    bl __trunctfdf2
+; CHECK-NEXT:    str q0, [sp] // 16-byte Folded Spill
+; CHECK-NEXT:    ldr q0, [sp, #16] // 16-byte Folded Reload
+; CHECK-NEXT:    bl __trunctfdf2
+; CHECK-NEXT:    ldr q1, [sp] // 16-byte Folded Reload
+; CHECK-NEXT:    // kill: def $d0 killed $d0 def $z0
+; CHECK-NEXT:    add x8, sp, #128
+; CHECK-NEXT:    mov v0.d[1], v1.d[0]
+; CHECK-NEXT:    str z0, [x8, #1, mul vl] // 16-byte Folded Spill
+; CHECK-NEXT:    ldr q0, [sp, #32] // 16-byte Folded Reload
+; CHECK-NEXT:    bl __trunctfdf2
+; CHECK-NEXT:    str q0, [sp, #32] // 16-byte Folded Spill
+; CHECK-NEXT:    ldr q0, [sp, #48] // 16-byte Folded Reload
+; CHECK-NEXT:    bl __trunctfdf2
+; CHECK-NEXT:    ldr q1, [sp, #32] // 16-byte Folded Reload
+; CHECK-NEXT:    add x8, sp, #128
+; CHECK-NEXT:    // kill: def $d0 killed $d0 def $z0
+; CHECK-NEXT:    ptrue p0.d, vl2
+; CHECK-NEXT:    mov v0.d[1], v1.d[0]
+; CHECK-NEXT:    ldr z1, [x8, #1, mul vl] // 16-byte Folded Reload
+; CHECK-NEXT:    splice z0.d, p0, z0.d, z1.d
+; CHECK-NEXT:    str z0, [x8, #1, mul vl] // 16-byte Folded Spill
+; CHECK-NEXT:    ldr q0, [sp, #64] // 16-byte Folded Reload
+; CHECK-NEXT:    bl __trunctfdf2
+; CHECK-NEXT:    str q0, [sp, #64] // 16-byte Folded Spill
+; CHECK-NEXT:    ldr q0, [sp, #80] // 16-byte Folded Reload
+; CHECK-NEXT:    bl __trunctfdf2
+; CHECK-NEXT:    ldr q1, [sp, #64] // 16-byte Folded Reload
+; CHECK-NEXT:    // kill: def $d0 killed $d0 def $z0
+; CHECK-NEXT:    add x8, sp, #128
+; CHECK-NEXT:    mov v0.d[1], v1.d[0]
+; CHECK-NEXT:    str z0, [x8] // 16-byte Folded Spill
+; CHECK-NEXT:    ldr q0, [sp, #96] // 16-byte Folded Reload
+; CHECK-NEXT:    bl __trunctfdf2
+; CHECK-NEXT:    str q0, [sp, #96] // 16-byte Folded Spill
+; CHECK-NEXT:    ldr q0, [sp, #112] // 16-byte Folded Reload
+; CHECK-NEXT:    bl __trunctfdf2
+; CHECK-NEXT:    ldr q1, [sp, #96] // 16-byte Folded Reload
+; CHECK-NEXT:    add x9, sp, #128
+; CHECK-NEXT:    // kill: def $d0 killed $d0 def $z0
+; CHECK-NEXT:    mov x8, #4
+; CHECK-NEXT:    ptrue p0.d, vl2
+; CHECK-NEXT:    mov v0.d[1], v1.d[0]
+; CHECK-NEXT:    ldr z1, [x9] // 16-byte Folded Reload
+; CHECK-NEXT:    splice z0.d, p0, z0.d, z1.d
+; CHECK-NEXT:    ptrue p0.d, vl4
+; CHECK-NEXT:    st1d { z0.d }, p0, [x19, x8, lsl #3]
+; CHECK-NEXT:    add x8, sp, #128
+; CHECK-NEXT:    ldr z0, [x8, #1, mul vl] // 16-byte Folded Reload
+; CHECK-NEXT:    st1d { z0.d }, p0, [x19]
+; CHECK-NEXT:    addvl sp, sp, #2
+; CHECK-NEXT:    add sp, sp, #128
+; CHECK-NEXT:    ldp x30, x19, [sp, #16] // 16-byte Folded Reload
+; CHECK-NEXT:    ldr x29, [sp], #32 // 8-byte Folded Reload
+; CHECK-NEXT:    ret
+  %op1 = load <8 x fp128>, ptr %a
+  %res = fptrunc <8 x fp128> %op1 to <8 x double>
+  store <8 x double> %res, ptr %b
+  ret void
+}
+
+attributes #0 = { nounwind "target-features"="+sve" }