diff --git a/lib/Target/AMDGPU/SIISelLowering.cpp b/lib/Target/AMDGPU/SIISelLowering.cpp
index a3135a78763..d9027284850 100644
--- a/lib/Target/AMDGPU/SIISelLowering.cpp
+++ b/lib/Target/AMDGPU/SIISelLowering.cpp
@@ -11690,3 +11690,18 @@ bool SITargetLowering::requiresUniformRegister(MachineFunction &MF,
   SmallPtrSet<const Value *, 16> Visited;
   return hasCFUser(V, Visited, Subtarget->getWavefrontSize());
 }
+
+std::pair<int, MVT>
+SITargetLowering::getTypeLegalizationCost(const DataLayout &DL,
+                                          Type *Ty) const {
+  auto Cost = TargetLoweringBase::getTypeLegalizationCost(DL, Ty);
+  auto Size = DL.getTypeSizeInBits(Ty);
+  // Maximum load or store can handle 8 dwords for scalar and 4 for
+  // vector ALU. Let's assume anything above 8 dwords is expensive
+  // even if legal.
+  if (Size <= 256)
+    return Cost;
+
+  Cost.first = (Size + 255) / 256;
+  return Cost;
+}
diff --git a/lib/Target/AMDGPU/SIISelLowering.h b/lib/Target/AMDGPU/SIISelLowering.h
index ffe9140d3d0..f4c07646405 100644
--- a/lib/Target/AMDGPU/SIISelLowering.h
+++ b/lib/Target/AMDGPU/SIISelLowering.h
@@ -464,6 +464,9 @@ public:
                                       MachineFunction &MF,
                                       const SIRegisterInfo &TRI,
                                       SIMachineFunctionInfo &Info) const;
+
+  std::pair<int, MVT> getTypeLegalizationCost(const DataLayout &DL,
+                                              Type *Ty) const;
 };
 
 } // End namespace llvm
diff --git a/test/Analysis/CostModel/AMDGPU/add-sub.ll b/test/Analysis/CostModel/AMDGPU/add-sub.ll
index 9a2c01058b2..609769fd514 100644
--- a/test/Analysis/CostModel/AMDGPU/add-sub.ll
+++ b/test/Analysis/CostModel/AMDGPU/add-sub.ll
@@ -90,7 +90,7 @@ define amdgpu_kernel void @add_v4i64(<4 x i64> addrspace(1)* %out, <4 x i64> add
 }
 
 ; ALL: 'add_v16i64'
-; ALL: estimated cost of 32 for {{.*}} add <16 x i64>
+; ALL: estimated cost of 128 for {{.*}} add <16 x i64>
 define amdgpu_kernel void @add_v16i64(<16 x i64> addrspace(1)* %out, <16 x i64> addrspace(1)* %vaddr, <16 x i64> %b) #0 {
   %vec = load <16 x i64>, <16 x i64> addrspace(1)* %vaddr
   %add = add <16 x i64> %vec, %b
diff --git a/test/Analysis/CostModel/AMDGPU/mul.ll b/test/Analysis/CostModel/AMDGPU/mul.ll
index 4d8a66ecd42..fa36d391f9c 100644
--- a/test/Analysis/CostModel/AMDGPU/mul.ll
+++ b/test/Analysis/CostModel/AMDGPU/mul.ll
@@ -90,7 +90,7 @@ define amdgpu_kernel void @mul_v4i64(<4 x i64> addrspace(1)* %out, <4 x i64> add
 
 
 ; ALL: 'mul_v8i64'
-; ALL: estimated cost of 128 for {{.*}} mul <8 x i64>
+; ALL: estimated cost of 256 for {{.*}} mul <8 x i64>
 define amdgpu_kernel void @mul_v8i64(<8 x i64> addrspace(1)* %out, <8 x i64> addrspace(1)* %vaddr, <8 x i64> %b) #0 {
   %vec = load <8 x i64>, <8 x i64> addrspace(1)* %vaddr
   %mul = mul <8 x i64> %vec, %b