Index: llvm/lib/CodeGen/SelectionDAG/SelectionDAG.cpp
===================================================================
--- llvm/lib/CodeGen/SelectionDAG/SelectionDAG.cpp
+++ llvm/lib/CodeGen/SelectionDAG/SelectionDAG.cpp
@@ -1942,10 +1942,8 @@
 
 SDValue SelectionDAG::getVScale(const SDLoc &DL, EVT VT, APInt MulImm,
                                 bool ConstantFold) {
-  assert(MulImm.getSignificantBits() <= VT.getSizeInBits() &&
-         "Immediate does not fit VT");
-
-  MulImm = MulImm.sextOrTrunc(VT.getSizeInBits());
+  assert(MulImm.getBitWidth() == VT.getSizeInBits() &&
+         "APInt size does not match type size!");
 
   if (ConstantFold) {
     const MachineFunction &MF = getMachineFunction();
@@ -5751,7 +5749,8 @@
     if (OpOpcode == ISD::UNDEF)
       return getUNDEF(VT);
     if (OpOpcode == ISD::VSCALE && !NewNodesMustHaveLegalTypes)
-      return getVScale(DL, VT, N1.getConstantOperandAPInt(0));
+      return getVScale(DL, VT,
+                       N1.getConstantOperandAPInt(0).trunc(VT.getSizeInBits()));
     break;
   case ISD::ANY_EXTEND_VECTOR_INREG:
   case ISD::ZERO_EXTEND_VECTOR_INREG:
Index: llvm/test/CodeGen/AArch64/sve-vscale.ll
===================================================================
--- llvm/test/CodeGen/AArch64/sve-vscale.ll
+++ llvm/test/CodeGen/AArch64/sve-vscale.ll
@@ -101,6 +101,17 @@
   ret i32 %1
 }
 
+define i1 @rdvl_i1() {
+; CHECK-LABEL: rdvl_i1:
+; CHECK:         rdvl x8, #-1
+; CHECK-NEXT:    asr x8, x8, #4
+; CHECK-NEXT:    and w0, w8, #0x1
+; CHECK-NEXT:    ret
+  %a = tail call i64 @llvm.vscale.i64()
+  %b = trunc i64 %a to i1
+  ret i1 %b
+}
+
 ;
 ; CNTH
 ;