Index: llvm/lib/Target/AArch64/AArch64TargetTransformInfo.h
===================================================================
--- llvm/lib/Target/AArch64/AArch64TargetTransformInfo.h
+++ llvm/lib/Target/AArch64/AArch64TargetTransformInfo.h
@@ -127,6 +127,10 @@
 
   unsigned getMaxInterleaveFactor(unsigned VF);
 
+  InstructionCost getMaskedMemoryOpCost(unsigned Opcode, Type *Src,
+                                        Align Alignment, unsigned AddressSpace,
+                                        TTI::TargetCostKind CostKind);
+
   InstructionCost getGatherScatterOpCost(unsigned Opcode, Type *DataTy,
                                          const Value *Ptr, bool VariableMask,
                                          Align Alignment,
Index: llvm/lib/Target/AArch64/AArch64TargetTransformInfo.cpp
===================================================================
--- llvm/lib/Target/AArch64/AArch64TargetTransformInfo.cpp
+++ llvm/lib/Target/AArch64/AArch64TargetTransformInfo.cpp
@@ -915,6 +915,22 @@
   return Options;
 }
 
+InstructionCost
+AArch64TTIImpl::getMaskedMemoryOpCost(unsigned Opcode, Type *Src, Align Alignment,
+                                      unsigned AddressSpace,
+                                      TTI::TargetCostKind CostKind) {
+  if (!isa<ScalableVectorType>(Src)) {
+    // This involves a comparison, a branch and the load/store itself. The
+    // single scalar cost of 8 is an estimate to reflect the expense of the
+    // branch.
+    unsigned ScalarCost = 8;
+    if (auto *VecTy = dyn_cast<FixedVectorType>(Src))
+      ScalarCost *= VecTy->getNumElements();
+    return ScalarCost;
+  }
+  return 2;
+}
+
 InstructionCost AArch64TTIImpl::getGatherScatterOpCost(
     unsigned Opcode, Type *DataTy, const Value *Ptr, bool VariableMask,
     Align Alignment, TTI::TargetCostKind CostKind, const Instruction *I) {
Index: llvm/test/Transforms/LoopVectorize/AArch64/masked-op-cost.ll
===================================================================
--- /dev/null
+++ llvm/test/Transforms/LoopVectorize/AArch64/masked-op-cost.ll
@@ -0,0 +1,92 @@
+; REQUIRES: asserts
+; RUN: opt -loop-vectorize -force-vector-interleave=1 -S -debug < %s 2>%t | FileCheck %s
+; RUN: cat %t | FileCheck %s --check-prefix=CHECK-COST
+
+target triple = "aarch64-unknown-linux-gnu"
+
+; CHECK-COST: Checking a loop in "fixed_width"
+; CHECK-COST: Found an estimated cost of 16 for VF 2 For instruction:   store i32 2, i32* %arrayidx1, align 4
+; CHECK-COST: Found an estimated cost of 32 for VF 4 For instruction:   store i32 2, i32* %arrayidx1, align 4
+; CHECK-COST: Selecting VF: 1.
+
+; We should decide this loop is not worth vectorising using fixed width vectors
+define void @fixed_width(i32* noalias nocapture %a, i32* noalias nocapture readonly %b, i64 %n) #0 {
+; CHECK-LABEL: @fixed_width(
+; CHECK-NOT: vector.body
+entry:
+  %cmp6 = icmp sgt i64 %n, 0
+  br i1 %cmp6, label %for.body.preheader, label %for.cond.cleanup
+
+for.body.preheader:                               ; preds = %entry
+  br label %for.body
+
+for.cond.cleanup.loopexit:                        ; preds = %for.inc
+  br label %for.cond.cleanup
+
+for.cond.cleanup:                                 ; preds = %for.cond.cleanup.loopexit, %entry
+  ret void
+
+for.body:                                         ; preds = %for.body.preheader, %for.inc
+  %i.07 = phi i64 [ %inc, %for.inc ], [ 0, %for.body.preheader ]
+  %arrayidx = getelementptr inbounds i32, i32* %b, i64 %i.07
+  %0 = load i32, i32* %arrayidx, align 4
+  %tobool.not = icmp eq i32 %0, 0
+  br i1 %tobool.not, label %for.inc, label %if.then
+
+if.then:                                          ; preds = %for.body
+  %arrayidx1 = getelementptr inbounds i32, i32* %a, i64 %i.07
+  store i32 2, i32* %arrayidx1, align 4
+  br label %for.inc
+
+for.inc:                                          ; preds = %for.body, %if.then
+  %inc = add nuw nsw i64 %i.07, 1
+  %exitcond.not = icmp eq i64 %inc, %n
+  br i1 %exitcond.not, label %for.cond.cleanup.loopexit, label %for.body
+}
+
+
+; CHECK-COST: Checking a loop in "scalable"
+; CHECK-COST: Found an estimated cost of 2 for VF vscale x 4 For instruction:   store i32 2, i32* %arrayidx1, align 4
+
+define void @scalable(i32* noalias nocapture %a, i32* noalias nocapture readonly %b, i64 %n) #0 {
+; CHECK-LABEL: @scalable(
+; CHECK: vector.body
+; CHECK: call void @llvm.masked.store.nxv4i32.p0nxv4i32
+entry:
+  %cmp6 = icmp sgt i64 %n, 0
+  br i1 %cmp6, label %for.body.preheader, label %for.cond.cleanup
+
+for.body.preheader:                               ; preds = %entry
+  br label %for.body
+
+for.cond.cleanup.loopexit:                        ; preds = %for.inc
+  br label %for.cond.cleanup
+
+for.cond.cleanup:                                 ; preds = %for.cond.cleanup.loopexit, %entry
+  ret void
+
+for.body:                                         ; preds = %for.body.preheader, %for.inc
+  %i.07 = phi i64 [ %inc, %for.inc ], [ 0, %for.body.preheader ]
+  %arrayidx = getelementptr inbounds i32, i32* %b, i64 %i.07
+  %0 = load i32, i32* %arrayidx, align 4
+  %tobool.not = icmp eq i32 %0, 0
+  br i1 %tobool.not, label %for.inc, label %if.then
+
+if.then:                                          ; preds = %for.body
+  %arrayidx1 = getelementptr inbounds i32, i32* %a, i64 %i.07
+  store i32 2, i32* %arrayidx1, align 4
+  br label %for.inc
+
+for.inc:                                          ; preds = %for.body, %if.then
+  %inc = add nuw nsw i64 %i.07, 1
+  %exitcond.not = icmp eq i64 %inc, %n
+  br i1 %exitcond.not, label %for.cond.cleanup.loopexit, label %for.body, !llvm.loop !0
+}
+
+attributes #0 = { "target-features"="+neon,+sve" }
+
+!0 = distinct !{!0, !1, !2, !3, !4}
+!1 = !{!"llvm.loop.mustprogress"}
+!2 = !{!"llvm.loop.vectorize.width", i32 4}
+!3 = !{!"llvm.loop.vectorize.scalable.enable", i1 true}
+!4 = !{!"llvm.loop.vectorize.enable", i1 true}