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
@@ -1459,7 +1459,8 @@
       setOperationAction(ISD::VECREDUCE_FMIN, VT, Custom);
       setOperationAction(ISD::VECREDUCE_FMAXIMUM, VT, Custom);
       setOperationAction(ISD::VECREDUCE_FMINIMUM, VT, Custom);
-      setOperationAction(ISD::VECREDUCE_SEQ_FADD, VT, Custom);
+      if (Subtarget->isSVEAvailable())
+        setOperationAction(ISD::VECREDUCE_SEQ_FADD, VT, Custom);
       setOperationAction(ISD::VECTOR_SPLICE, VT, Custom);
       setOperationAction(ISD::VECTOR_DEINTERLEAVE, VT, Custom);
       setOperationAction(ISD::VECTOR_INTERLEAVE, VT, Custom);
@@ -1519,9 +1520,12 @@
     setOperationAction(ISD::MUL, MVT::v1i64, Custom);
     setOperationAction(ISD::MUL, MVT::v2i64, Custom);
 
-    // NEON doesn't support across-vector reductions, but SVE does.
-    for (auto VT : {MVT::v4f16, MVT::v8f16, MVT::v2f32, MVT::v4f32, MVT::v2f64})
-      setOperationAction(ISD::VECREDUCE_SEQ_FADD, VT, Custom);
+    if (Subtarget->isSVEAvailable()) {
+      // NEON doesn't support across-vector reductions, but SVE does.
+      for (auto VT :
+           {MVT::v4f16, MVT::v8f16, MVT::v2f32, MVT::v4f32, MVT::v2f64})
+        setOperationAction(ISD::VECREDUCE_SEQ_FADD, VT, Custom);
+    }
 
     if (!Subtarget->isNeonAvailable()) {
       setTruncStoreAction(MVT::v2f32, MVT::v2f16, Custom);
@@ -1879,7 +1883,8 @@
   setOperationAction(ISD::VECREDUCE_FMAXIMUM, VT, Custom);
   setOperationAction(ISD::VECREDUCE_FMINIMUM, VT, Custom);
   setOperationAction(ISD::VECREDUCE_OR, VT, Custom);
-  setOperationAction(ISD::VECREDUCE_SEQ_FADD, VT, Custom);
+  setOperationAction(ISD::VECREDUCE_SEQ_FADD, VT,
+                     StreamingSVE ? Expand : Custom);
   setOperationAction(ISD::VECREDUCE_SMAX, VT, Custom);
   setOperationAction(ISD::VECREDUCE_SMIN, VT, Custom);
   setOperationAction(ISD::VECREDUCE_UMAX, VT, Custom);
diff --git a/llvm/lib/Target/AArch64/AArch64Subtarget.h b/llvm/lib/Target/AArch64/AArch64Subtarget.h
--- a/llvm/lib/Target/AArch64/AArch64Subtarget.h
+++ b/llvm/lib/Target/AArch64/AArch64Subtarget.h
@@ -204,20 +204,28 @@
 
   bool isXRaySupported() const override { return true; }
 
-  /// Returns true if the function has the streaming attribute.
+  /// Returns true if the function has a streaming body.
   bool isStreaming() const { return StreamingSVEMode; }
 
-  /// Returns true if the function has the streaming-compatible attribute.
-  bool isStreamingCompatible() const { return StreamingCompatibleSVEMode; }
+  /// Returns true if the function has a streaming-compatible body.
+  bool isStreamingCompatible() const;
 
   /// Returns true if the target has NEON and the function at runtime is known
   /// to have NEON enabled (e.g. the function is known not to be in streaming-SVE
   /// mode, which disables NEON instructions).
   bool isNeonAvailable() const;
 
+  /// Returns true if the target has SVE and can use the full range of SVE
+  /// instructions, for example because it knows the function is known not to be
+  /// in streaming-SVE mode or when the target has FEAT_FA64 enabled.
+  bool isSVEAvailable() const;
+
   unsigned getMinVectorRegisterBitWidth() const {
-    // Don't assume any minimum vector size when PSTATE.SM may not be 0.
-    if (StreamingSVEMode || StreamingCompatibleSVEMode)
+    // Don't assume any minimum vector size when PSTATE.SM may not be 0, because
+    // we don't yet support streaming-compatible codegen support that we trust
+    // is safe for functions that may be executed in streaming-SVE mode.
+    // By returning '0' here, we disable vectorization.
+    if (!isSVEAvailable() && !isNeonAvailable())
       return 0;
     return MinVectorRegisterBitWidth;
   }
diff --git a/llvm/lib/Target/AArch64/AArch64Subtarget.cpp b/llvm/lib/Target/AArch64/AArch64Subtarget.cpp
--- a/llvm/lib/Target/AArch64/AArch64Subtarget.cpp
+++ b/llvm/lib/Target/AArch64/AArch64Subtarget.cpp
@@ -477,14 +477,16 @@
 
 bool AArch64Subtarget::useAA() const { return UseAA; }
 
-bool AArch64Subtarget::isNeonAvailable() const {
-  if (!hasNEON())
-    return false;
+bool AArch64Subtarget::isStreamingCompatible() const {
+  return StreamingCompatibleSVEMode || ForceStreamingCompatibleSVE;
+}
 
-  // The 'force-streaming-comaptible-sve' flag overrides the streaming
-  // function attributes.
-  if (ForceStreamingCompatibleSVE.getNumOccurrences() > 0)
-    return !ForceStreamingCompatibleSVE;
+bool AArch64Subtarget::isNeonAvailable() const {
+  return hasNEON() && !isStreaming() && !isStreamingCompatible();
+}
 
-  return !isStreaming() && !isStreamingCompatible();
+bool AArch64Subtarget::isSVEAvailable() const{
+  // FIXME: Also return false if FEAT_FA64 is set, but we can't do this yet
+  // as we don't yet support the feature in LLVM.
+  return hasSVE() && !isStreaming() && !isStreamingCompatible();
 }
diff --git a/llvm/lib/Target/AArch64/AArch64TargetTransformInfo.cpp b/llvm/lib/Target/AArch64/AArch64TargetTransformInfo.cpp
--- a/llvm/lib/Target/AArch64/AArch64TargetTransformInfo.cpp
+++ b/llvm/lib/Target/AArch64/AArch64TargetTransformInfo.cpp
@@ -1943,8 +1943,7 @@
 
     return TypeSize::getFixed(ST->hasNEON() ? 128 : 0);
   case TargetTransformInfo::RGK_ScalableVector:
-    if ((ST->isStreaming() || ST->isStreamingCompatible()) &&
-        !EnableScalableAutovecInStreamingMode)
+    if (!ST->isSVEAvailable() && !EnableScalableAutovecInStreamingMode)
       return TypeSize::getScalable(0);
 
     return TypeSize::getScalable(ST->hasSVE() ? 128 : 0);
diff --git a/llvm/test/CodeGen/AArch64/sve-fp-reduce-fadda.ll b/llvm/test/CodeGen/AArch64/sve-fp-reduce-fadda.ll
--- a/llvm/test/CodeGen/AArch64/sve-fp-reduce-fadda.ll
+++ b/llvm/test/CodeGen/AArch64/sve-fp-reduce-fadda.ll
@@ -1,8 +1,8 @@
 ; NOTE: Assertions have been autogenerated by utils/update_llc_test_checks.py
 ; RUN: llc -mattr=+sve < %s | FileCheck %s
 
-; FIXME: Streaming-compatible SVE doesn't include FADDA, so this shouldn't compile!
-; RUN: llc -mattr=+sve -force-streaming-compatible-sve < %s | FileCheck %s
+; Streaming-compatible SVE doesn't include FADDA, so this shouldn't compile!
+; RUN: not --crash llc -mattr=+sve -force-streaming-compatible-sve < %s
 
 target triple = "aarch64-linux-gnu"
 
diff --git a/llvm/test/CodeGen/AArch64/sve-streaming-mode-fixed-length-fp-reduce.ll b/llvm/test/CodeGen/AArch64/sve-streaming-mode-fixed-length-fp-reduce.ll
--- a/llvm/test/CodeGen/AArch64/sve-streaming-mode-fixed-length-fp-reduce.ll
+++ b/llvm/test/CodeGen/AArch64/sve-streaming-mode-fixed-length-fp-reduce.ll
@@ -10,11 +10,14 @@
 define half @fadda_v4f16(half %start, <4 x half> %a) {
 ; CHECK-LABEL: fadda_v4f16:
 ; CHECK:       // %bb.0:
-; CHECK-NEXT:    ptrue p0.h, vl4
-; CHECK-NEXT:    // kill: def $h0 killed $h0 def $z0
 ; CHECK-NEXT:    // kill: def $d1 killed $d1 def $z1
-; CHECK-NEXT:    fadda h0, p0, h0, z1.h
-; CHECK-NEXT:    // kill: def $h0 killed $h0 killed $z0
+; CHECK-NEXT:    fadd h0, h0, h1
+; CHECK-NEXT:    mov z2.h, z1.h[1]
+; CHECK-NEXT:    fadd h0, h0, h2
+; CHECK-NEXT:    mov z2.h, z1.h[2]
+; CHECK-NEXT:    mov z1.h, z1.h[3]
+; CHECK-NEXT:    fadd h0, h0, h2
+; CHECK-NEXT:    fadd h0, h0, h1
 ; CHECK-NEXT:    ret
   %res = call half @llvm.vector.reduce.fadd.v4f16(half %start, <4 x half> %a)
   ret half %res
@@ -23,11 +26,22 @@
 define half @fadda_v8f16(half %start, <8 x half> %a) {
 ; CHECK-LABEL: fadda_v8f16:
 ; CHECK:       // %bb.0:
-; CHECK-NEXT:    ptrue p0.h, vl8
-; CHECK-NEXT:    // kill: def $h0 killed $h0 def $z0
 ; CHECK-NEXT:    // kill: def $q1 killed $q1 def $z1
-; CHECK-NEXT:    fadda h0, p0, h0, z1.h
-; CHECK-NEXT:    // kill: def $h0 killed $h0 killed $z0
+; CHECK-NEXT:    fadd h0, h0, h1
+; CHECK-NEXT:    mov z2.h, z1.h[1]
+; CHECK-NEXT:    fadd h0, h0, h2
+; CHECK-NEXT:    mov z2.h, z1.h[2]
+; CHECK-NEXT:    fadd h0, h0, h2
+; CHECK-NEXT:    mov z2.h, z1.h[3]
+; CHECK-NEXT:    fadd h0, h0, h2
+; CHECK-NEXT:    mov z2.h, z1.h[4]
+; CHECK-NEXT:    fadd h0, h0, h2
+; CHECK-NEXT:    mov z2.h, z1.h[5]
+; CHECK-NEXT:    fadd h0, h0, h2
+; CHECK-NEXT:    mov z2.h, z1.h[6]
+; CHECK-NEXT:    mov z1.h, z1.h[7]
+; CHECK-NEXT:    fadd h0, h0, h2
+; CHECK-NEXT:    fadd h0, h0, h1
 ; CHECK-NEXT:    ret
   %res = call half @llvm.vector.reduce.fadd.v8f16(half %start, <8 x half> %a)
   ret half %res
@@ -36,13 +50,38 @@
 define half @fadda_v16f16(half %start, ptr %a) {
 ; CHECK-LABEL: fadda_v16f16:
 ; CHECK:       // %bb.0:
-; CHECK-NEXT:    ptrue p0.h, vl8
 ; CHECK-NEXT:    ldr q1, [x0]
-; CHECK-NEXT:    // kill: def $h0 killed $h0 def $z0
-; CHECK-NEXT:    fadda h0, p0, h0, z1.h
+; CHECK-NEXT:    fadd h0, h0, h1
+; CHECK-NEXT:    mov z2.h, z1.h[1]
+; CHECK-NEXT:    fadd h0, h0, h2
+; CHECK-NEXT:    mov z2.h, z1.h[2]
+; CHECK-NEXT:    fadd h0, h0, h2
+; CHECK-NEXT:    mov z2.h, z1.h[3]
+; CHECK-NEXT:    fadd h0, h0, h2
+; CHECK-NEXT:    mov z2.h, z1.h[4]
+; CHECK-NEXT:    fadd h0, h0, h2
+; CHECK-NEXT:    mov z2.h, z1.h[5]
+; CHECK-NEXT:    fadd h0, h0, h2
+; CHECK-NEXT:    mov z2.h, z1.h[6]
+; CHECK-NEXT:    mov z1.h, z1.h[7]
+; CHECK-NEXT:    fadd h0, h0, h2
+; CHECK-NEXT:    fadd h0, h0, h1
 ; CHECK-NEXT:    ldr q1, [x0, #16]
-; CHECK-NEXT:    fadda h0, p0, h0, z1.h
-; CHECK-NEXT:    // kill: def $h0 killed $h0 killed $z0
+; CHECK-NEXT:    mov z2.h, z1.h[1]
+; CHECK-NEXT:    fadd h0, h0, h1
+; CHECK-NEXT:    fadd h0, h0, h2
+; CHECK-NEXT:    mov z2.h, z1.h[2]
+; CHECK-NEXT:    fadd h0, h0, h2
+; CHECK-NEXT:    mov z2.h, z1.h[3]
+; CHECK-NEXT:    fadd h0, h0, h2
+; CHECK-NEXT:    mov z2.h, z1.h[4]
+; CHECK-NEXT:    fadd h0, h0, h2
+; CHECK-NEXT:    mov z2.h, z1.h[5]
+; CHECK-NEXT:    fadd h0, h0, h2
+; CHECK-NEXT:    mov z2.h, z1.h[6]
+; CHECK-NEXT:    mov z1.h, z1.h[7]
+; CHECK-NEXT:    fadd h0, h0, h2
+; CHECK-NEXT:    fadd h0, h0, h1
 ; CHECK-NEXT:    ret
   %op = load <16 x half>, ptr %a
   %res = call half @llvm.vector.reduce.fadd.v16f16(half %start, <16 x half> %op)
@@ -52,11 +91,10 @@
 define float @fadda_v2f32(float %start, <2 x float> %a) {
 ; CHECK-LABEL: fadda_v2f32:
 ; CHECK:       // %bb.0:
-; CHECK-NEXT:    ptrue p0.s, vl2
-; CHECK-NEXT:    // kill: def $s0 killed $s0 def $z0
 ; CHECK-NEXT:    // kill: def $d1 killed $d1 def $z1
-; CHECK-NEXT:    fadda s0, p0, s0, z1.s
-; CHECK-NEXT:    // kill: def $s0 killed $s0 killed $z0
+; CHECK-NEXT:    fadd s0, s0, s1
+; CHECK-NEXT:    mov z1.s, z1.s[1]
+; CHECK-NEXT:    fadd s0, s0, s1
 ; CHECK-NEXT:    ret
   %res = call float @llvm.vector.reduce.fadd.v2f32(float %start, <2 x float> %a)
   ret float %res
@@ -65,11 +103,14 @@
 define float @fadda_v4f32(float %start, <4 x float> %a) {
 ; CHECK-LABEL: fadda_v4f32:
 ; CHECK:       // %bb.0:
-; CHECK-NEXT:    ptrue p0.s, vl4
-; CHECK-NEXT:    // kill: def $s0 killed $s0 def $z0
 ; CHECK-NEXT:    // kill: def $q1 killed $q1 def $z1
-; CHECK-NEXT:    fadda s0, p0, s0, z1.s
-; CHECK-NEXT:    // kill: def $s0 killed $s0 killed $z0
+; CHECK-NEXT:    fadd s0, s0, s1
+; CHECK-NEXT:    mov z2.s, z1.s[1]
+; CHECK-NEXT:    fadd s0, s0, s2
+; CHECK-NEXT:    mov z2.s, z1.s[2]
+; CHECK-NEXT:    mov z1.s, z1.s[3]
+; CHECK-NEXT:    fadd s0, s0, s2
+; CHECK-NEXT:    fadd s0, s0, s1
 ; CHECK-NEXT:    ret
   %res = call float @llvm.vector.reduce.fadd.v4f32(float %start, <4 x float> %a)
   ret float %res
@@ -78,13 +119,22 @@
 define float @fadda_v8f32(float %start, ptr %a) {
 ; CHECK-LABEL: fadda_v8f32:
 ; CHECK:       // %bb.0:
-; CHECK-NEXT:    ptrue p0.s, vl4
 ; CHECK-NEXT:    ldr q1, [x0]
-; CHECK-NEXT:    // kill: def $s0 killed $s0 def $z0
-; CHECK-NEXT:    fadda s0, p0, s0, z1.s
+; CHECK-NEXT:    fadd s0, s0, s1
+; CHECK-NEXT:    mov z2.s, z1.s[1]
+; CHECK-NEXT:    fadd s0, s0, s2
+; CHECK-NEXT:    mov z2.s, z1.s[2]
+; CHECK-NEXT:    mov z1.s, z1.s[3]
+; CHECK-NEXT:    fadd s0, s0, s2
+; CHECK-NEXT:    fadd s0, s0, s1
 ; CHECK-NEXT:    ldr q1, [x0, #16]
-; CHECK-NEXT:    fadda s0, p0, s0, z1.s
-; CHECK-NEXT:    // kill: def $s0 killed $s0 killed $z0
+; CHECK-NEXT:    mov z2.s, z1.s[1]
+; CHECK-NEXT:    fadd s0, s0, s1
+; CHECK-NEXT:    fadd s0, s0, s2
+; CHECK-NEXT:    mov z2.s, z1.s[2]
+; CHECK-NEXT:    mov z1.s, z1.s[3]
+; CHECK-NEXT:    fadd s0, s0, s2
+; CHECK-NEXT:    fadd s0, s0, s1
 ; CHECK-NEXT:    ret
   %op = load <8 x float>, ptr %a
   %res = call float @llvm.vector.reduce.fadd.v8f32(float %start, <8 x float> %op)
@@ -104,11 +154,10 @@
 define double @fadda_v2f64(double %start, <2 x double> %a) {
 ; CHECK-LABEL: fadda_v2f64:
 ; CHECK:       // %bb.0:
-; CHECK-NEXT:    ptrue p0.d, vl2
-; CHECK-NEXT:    // kill: def $d0 killed $d0 def $z0
 ; CHECK-NEXT:    // kill: def $q1 killed $q1 def $z1
-; CHECK-NEXT:    fadda d0, p0, d0, z1.d
-; CHECK-NEXT:    // kill: def $d0 killed $d0 killed $z0
+; CHECK-NEXT:    fadd d0, d0, d1
+; CHECK-NEXT:    mov z1.d, z1.d[1]
+; CHECK-NEXT:    fadd d0, d0, d1
 ; CHECK-NEXT:    ret
   %res = call double @llvm.vector.reduce.fadd.v2f64(double %start, <2 x double> %a)
   ret double %res
@@ -117,13 +166,14 @@
 define double @fadda_v4f64(double %start, ptr %a) {
 ; CHECK-LABEL: fadda_v4f64:
 ; CHECK:       // %bb.0:
-; CHECK-NEXT:    ptrue p0.d, vl2
 ; CHECK-NEXT:    ldr q1, [x0]
-; CHECK-NEXT:    // kill: def $d0 killed $d0 def $z0
-; CHECK-NEXT:    fadda d0, p0, d0, z1.d
+; CHECK-NEXT:    fadd d0, d0, d1
+; CHECK-NEXT:    mov z1.d, z1.d[1]
+; CHECK-NEXT:    fadd d0, d0, d1
 ; CHECK-NEXT:    ldr q1, [x0, #16]
-; CHECK-NEXT:    fadda d0, p0, d0, z1.d
-; CHECK-NEXT:    // kill: def $d0 killed $d0 killed $z0
+; CHECK-NEXT:    fadd d0, d0, d1
+; CHECK-NEXT:    mov z1.d, z1.d[1]
+; CHECK-NEXT:    fadd d0, d0, d1
 ; CHECK-NEXT:    ret
   %op = load <4 x double>, ptr %a
   %res = call double @llvm.vector.reduce.fadd.v4f64(double %start, <4 x double> %op)