diff --git a/llvm/include/llvm/CodeGen/ValueTypes.h b/llvm/include/llvm/CodeGen/ValueTypes.h
--- a/llvm/include/llvm/CodeGen/ValueTypes.h
+++ b/llvm/include/llvm/CodeGen/ValueTypes.h
@@ -298,6 +298,7 @@
     }
 
     /// Given a vector type, return the number of elements it contains.
+    /// This assumes a fixed-vector type.
     unsigned getVectorNumElements() const {
 #ifdef STRICT_FIXED_SIZE_VECTORS
       assert(isFixedLengthVector() && "Invalid vector type!");
@@ -323,7 +324,8 @@
       return getExtendedVectorElementCount();
     }
 
-    /// Given a vector type, return the minimum number of elements it contains.
+    /// Given a (possibly scalable) vector type, return the minimum number of
+    /// elements it contains.
     unsigned getVectorMinNumElements() const {
       return getVectorElementCount().getKnownMinValue();
     }
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
@@ -15139,7 +15139,8 @@
     }
   }
 
-  if (N0.getOpcode() != ISD::SETCC || CCVT.getVectorNumElements() != 1 ||
+  if (N0.getOpcode() != ISD::SETCC ||
+      CCVT.getVectorElementCount() != ElementCount::getFixed(1) ||
       CCVT.getVectorElementType() != MVT::i1)
     return SDValue();
 
diff --git a/llvm/test/CodeGen/AArch64/sve-vselect-interface-warnings.ll b/llvm/test/CodeGen/AArch64/sve-vselect-interface-warnings.ll
new file mode 100644
--- /dev/null
+++ b/llvm/test/CodeGen/AArch64/sve-vselect-interface-warnings.ll
@@ -0,0 +1,49 @@
+; RUN: llc -mtriple=aarch64-linux-unknown -mattr=+sve -o - < %s 2>%t | FileCheck %s
+; RUN: FileCheck --check-prefix="WARN" --allow-empty %s <%t
+
+; If this check fails please read test/CodeGen/AArch64/README for instructions on how to resolve it.
+; WARN-NOT: warning
+
+define <vscale x 8 x i8> @vselect_cmp_ne(<vscale x 8 x i8> %a, <vscale x 8 x i8> %b, <vscale x 8 x i8> %c) {
+  ; CHECK-LABEL: vselect_cmp_ne
+  ; CHECK:       // %bb.0
+  ; CHECK-NEXT:    mov	z3.d, z1.d
+  ; CHECK-NEXT:    and	z3.h, z3.h, #0xff
+  ; CHECK-NEXT:    and	z0.h, z0.h, #0xff
+  ; CHECK-NEXT:    ptrue	p0.h
+  ; CHECK-NEXT:    cmpne	p0.h, p0/z, z0.h, z3.h
+  ; CHECK-NEXT:    sel	z0.h, p0, z1.h, z2.h
+  ; CHECK-NEXT:    ret
+  %cmp = icmp ne <vscale x 8 x i8> %a, %b
+  %d = select <vscale x 8 x i1> %cmp, <vscale x 8 x i8> %b, <vscale x 8 x i8> %c
+  ret <vscale x 8 x i8> %d
+}
+
+define <vscale x 8 x i8> @vselect_cmp_sgt(<vscale x 8 x i8> %a, <vscale x 8 x i8> %b, <vscale x 8 x i8> %c) {
+  ; CHECK-LABEL: vselect_cmp_sgt
+  ; CHECK:       // %bb.0
+  ; CHECK-NEXT:    ptrue	p0.h
+  ; CHECK-NEXT:    sxtb	z3.h, p0/m, z1.h
+  ; CHECK-NEXT:    sxtb	z0.h, p0/m, z0.h
+  ; CHECK-NEXT:    cmpgt	p0.h, p0/z, z0.h, z3.h
+  ; CHECK-NEXT:    sel	z0.h, p0, z1.h, z2.h
+  ; CHECK-NEXT:    ret
+  %cmp = icmp sgt <vscale x 8 x i8> %a, %b
+  %d = select <vscale x 8 x i1> %cmp, <vscale x 8 x i8> %b, <vscale x 8 x i8> %c
+  ret <vscale x 8 x i8> %d
+}
+
+define <vscale x 8 x i8> @vselect_cmp_ugt(<vscale x 8 x i8> %a, <vscale x 8 x i8> %b, <vscale x 8 x i8> %c) {
+  ; CHECK-LABEL: vselect_cmp_ugt
+  ; CHECK:       // %bb.0
+  ; CHECK-NEXT:    mov	z3.d, z1.d
+  ; CHECK-NEXT:    and	z3.h, z3.h, #0xff
+  ; CHECK-NEXT:    and	z0.h, z0.h, #0xff
+  ; CHECK-NEXT:    ptrue	p0.h
+  ; CHECK-NEXT:    cmphi	p0.h, p0/z, z0.h, z3.h
+  ; CHECK-NEXT:    sel	z0.h, p0, z1.h, z2.h
+  ; CHECK-NEXT:    ret
+  %cmp = icmp ugt <vscale x 8 x i8> %a, %b
+  %d = select <vscale x 8 x i1> %cmp, <vscale x 8 x i8> %b, <vscale x 8 x i8> %c
+  ret <vscale x 8 x i8> %d
+}