diff --git a/lib/SPIRVProducerPass.cpp b/lib/SPIRVProducerPass.cpp
index e14671c66f..8c94427895 100644
--- a/lib/SPIRVProducerPass.cpp
+++ b/lib/SPIRVProducerPass.cpp
@@ -66,6 +66,11 @@ llvm::cl::opt<bool> distinct_kernel_descriptor_sets(
     llvm::cl::desc(
         "Each kernel uses its own descriptor set for its arguments"));
 
+llvm::cl::opt<bool> hack_undef(
+    "hack-undef", llvm::cl::init(false),
+    llvm::cl::desc(
+        "Use OpConstantNull instead of OpUndef"));
+
 enum SPIRVOperandType {
   NUMBERID,
   LITERAL_INTEGER,
@@ -1971,7 +1976,7 @@ void SPIRVProducerPass::GenerateSPIRVConstants() {
 
     if (isa<UndefValue>(Cst)) {
       // Ops[0] = Result Type ID
-      Opcode = spv::OpUndef;
+      Opcode = hack_undef ? spv::OpConstantNull : spv::OpUndef;
       WordCount = 3;
     } else if (const ConstantInt *CI = dyn_cast<ConstantInt>(Cst)) {
       unsigned BitWidth = CI->getBitWidth();
diff --git a/test/hack_undef.cl b/test/hack_undef.cl
new file mode 100644
index 0000000000..3abdeffbba
--- /dev/null
+++ b/test/hack_undef.cl
@@ -0,0 +1,64 @@
+// Test the -hack-undef option.
+// It's a workaround for https://github.com/google/clspv/issues/95
+
+// RUN: clspv %s -S -o %t.spvasm -hack-undef
+// RUN: FileCheck %s < %t.spvasm
+// RUN: clspv %s -o %t.spv -hack-undef
+// RUN: spirv-dis -o %t2.spvasm %t.spv
+// RUN: FileCheck %s < %t2.spvasm
+// RUN: spirv-val --target-env vulkan1.0 %t.spv
+
+void kernel foo(global float4* A)
+{
+  float4 value;
+  value.w = 1111.0f;
+  *A = value;
+}
+// CHECK: ; SPIR-V
+// CHECK: ; Version: 1.0
+// CHECK: ; Generator: Codeplay; 0
+// CHECK: ; Bound: 25
+// CHECK: ; Schema: 0
+// CHECK: OpCapability Shader
+// CHECK: OpCapability VariablePointers
+// CHECK: OpExtension "SPV_KHR_storage_buffer_storage_class"
+// CHECK: OpExtension "SPV_KHR_variable_pointers"
+// CHECK: OpMemoryModel Logical GLSL450
+// CHECK: OpEntryPoint GLCompute [[_22:%[a-zA-Z0-9_]+]] "foo"
+// CHECK: OpSource OpenCL_C 120
+// CHECK: OpDecorate [[_16:%[a-zA-Z0-9_]+]] SpecId 0
+// CHECK: OpDecorate [[_17:%[a-zA-Z0-9_]+]] SpecId 1
+// CHECK: OpDecorate [[_18:%[a-zA-Z0-9_]+]] SpecId 2
+// CHECK: OpDecorate [[__runtimearr_v4float:%[a-zA-Z0-9_]+]] ArrayStride 16
+// CHECK: OpMemberDecorate [[__struct_5:%[a-zA-Z0-9_]+]] 0 Offset 0
+// CHECK: OpDecorate [[__struct_5]] Block
+// CHECK: OpDecorate [[_gl_WorkGroupSize:%[a-zA-Z0-9_]+]] BuiltIn WorkgroupSize
+// CHECK: OpDecorate [[_21:%[a-zA-Z0-9_]+]] DescriptorSet 0
+// CHECK: OpDecorate [[_21]] Binding 0
+// CHECK: [[_float:%[a-zA-Z0-9_]+]] = OpTypeFloat 32
+// CHECK: [[_v4float:%[a-zA-Z0-9_]+]] = OpTypeVector [[_float]] 4
+// CHECK: [[__ptr_StorageBuffer_v4float:%[a-zA-Z0-9_]+]] = OpTypePointer StorageBuffer [[_v4float]]
+// CHECK: [[__runtimearr_v4float]] = OpTypeRuntimeArray [[_v4float]]
+// CHECK: [[__struct_5]] = OpTypeStruct [[__runtimearr_v4float]]
+// CHECK: [[__ptr_StorageBuffer__struct_5:%[a-zA-Z0-9_]+]] = OpTypePointer StorageBuffer [[__struct_5]]
+// CHECK: [[_uint:%[a-zA-Z0-9_]+]] = OpTypeInt 32 0
+// CHECK: [[_void:%[a-zA-Z0-9_]+]] = OpTypeVoid
+// CHECK: [[_9:%[a-zA-Z0-9_]+]] = OpTypeFunction [[_void]]
+// CHECK: [[_v3uint:%[a-zA-Z0-9_]+]] = OpTypeVector [[_uint]] 3
+// CHECK: [[__ptr_Private_v3uint:%[a-zA-Z0-9_]+]] = OpTypePointer Private [[_v3uint]]
+// CHECK: [[_uint_0:%[a-zA-Z0-9_]+]] = OpConstant [[_uint]] 0
+// CHECK: [[_13:%[a-zA-Z0-9_]+]] = OpConstantNull [[_float]]
+// CHECK: [[_float_1111:%[a-zA-Z0-9_]+]] = OpConstant [[_float]] 1111
+// CHECK: [[_15:%[a-zA-Z0-9_]+]] = OpConstantComposite [[_v4float]] [[_13]] [[_13]] [[_13]] [[_float_1111]]
+// CHECK: [[_16]] = OpSpecConstant [[_uint]] 1
+// CHECK: [[_17]] = OpSpecConstant [[_uint]] 1
+// CHECK: [[_18]] = OpSpecConstant [[_uint]] 1
+// CHECK: [[_gl_WorkGroupSize]] = OpSpecConstantComposite [[_v3uint]] [[_16]] [[_17]] [[_18]]
+// CHECK: [[_20:%[a-zA-Z0-9_]+]] = OpVariable [[__ptr_Private_v3uint]] Private [[_gl_WorkGroupSize]]
+// CHECK: [[_21]] = OpVariable [[__ptr_StorageBuffer__struct_5]] StorageBuffer
+// CHECK: [[_22]] = OpFunction [[_void]] None [[_9]]
+// CHECK: [[_23:%[a-zA-Z0-9_]+]] = OpLabel
+// CHECK: [[_24:%[a-zA-Z0-9_]+]] = OpAccessChain [[__ptr_StorageBuffer_v4float]] [[_21]] [[_uint_0]] [[_uint_0]]
+// CHECK: OpStore [[_24]] [[_15]]
+// CHECK: OpReturn
+// CHECK: OpFunctionEnd