diff --git a/external/SPIRV-Headers b/external/SPIRV-Headers
index 19e8350415..1380cbbec1 160000
--- a/external/SPIRV-Headers
+++ b/external/SPIRV-Headers
@@ -1 +1 @@
-Subproject commit 19e8350415ed9516c8afffa19ae2c58559495a67
+Subproject commit 1380cbbec10756b492e9397d03c4250887e15090
diff --git a/external/SPIRV-Tools b/external/SPIRV-Tools
index 5ed637caa3..d997c83b10 160000
--- a/external/SPIRV-Tools
+++ b/external/SPIRV-Tools
@@ -1 +1 @@
-Subproject commit 5ed637caa3a120e151712cd4c2f2f31bf1ee7211
+Subproject commit d997c83b103ed1f3af09ed65e1cbf89fbc6d9451
diff --git a/tools/clang/lib/SPIRV/SpirvEmitter.cpp b/tools/clang/lib/SPIRV/SpirvEmitter.cpp
index 2532730d9b..802e6a5482 100644
--- a/tools/clang/lib/SPIRV/SpirvEmitter.cpp
+++ b/tools/clang/lib/SPIRV/SpirvEmitter.cpp
@@ -12593,6 +12593,9 @@ bool SpirvEmitter::spirvToolsLegalize(std::vector<uint32_t> *mod,
   // Add flattening of resources if needed.
   if (spirvOptions.flattenResourceArrays ||
       declIdMapper.requiresFlatteningCompositeResources()) {
+    optimizer.RegisterPass(
+        spvtools::CreateReplaceDescArrayAccessUsingVarIndexPass());
+    optimizer.RegisterPass(spvtools::CreateAggressiveDCEPass());
     optimizer.RegisterPass(spvtools::CreateDescriptorScalarReplacementPass());
     // ADCE should be run after desc_sroa in order to remove potentially
     // illegal types such as structures containing opaque types.
diff --git a/tools/clang/test/CodeGenSPIRV/vk.binding.flatten-arrays.var-index.hlsl b/tools/clang/test/CodeGenSPIRV/vk.binding.flatten-arrays.var-index.hlsl
new file mode 100644
index 0000000000..8d8b0238f8
--- /dev/null
+++ b/tools/clang/test/CodeGenSPIRV/vk.binding.flatten-arrays.var-index.hlsl
@@ -0,0 +1,81 @@
+// Run: %dxc -T ps_6_0 -E main -fspv-flatten-resource-arrays -O3
+
+// CHECK: OpName %x_0_ "x[0]"
+// CHECK: OpName %x_1_ "x[1]"
+// CHECK: OpName %y_0_ "y[0]"
+// CHECK: OpName %y_1_ "y[1]"
+// CHECK: OpName %y_2_ "y[2]"
+// CHECK: OpDecorate %x_0_ DescriptorSet 0
+// CHECK: OpDecorate %x_0_ Binding 1
+// CHECK: OpDecorate %x_1_ DescriptorSet 0
+// CHECK: OpDecorate %x_1_ Binding 2
+// CHECK: OpDecorate %y_0_ DescriptorSet 0
+// CHECK: OpDecorate %y_0_ Binding 2
+// CHECK: OpDecorate %y_1_ DescriptorSet 0
+// CHECK: OpDecorate %y_1_ Binding 3
+// CHECK: OpDecorate %y_2_ DescriptorSet 0
+// CHECK: OpDecorate %y_2_ Binding 4
+
+SamplerState x[2]  : register(s1);
+Texture2D    y[3]  : register(t2);
+
+float4 main(uint instanceID : INSTANCEID, float2 texCoord : TEXCOORD) : SV_TARGET
+{
+// CHECK: [[instanceID:%\d+]] = OpLoad %uint %in_var_INSTANCEID
+// CHECK: [[texCoord:%\d+]] = OpLoad %v2float %in_var_TEXCOORD
+// CHECK: [[instanceID_idx:%\d+]] = OpUMod %uint [[instanceID]] %uint_2
+// CHECK:       OpSelectionMerge [[merge0:%\d+]] None
+// CHECK:       OpSwitch [[instanceID_idx]] [[default0:%\d+]] 0 [[sw0_bb0:%\d+]] 1 [[sw0_bb1:%\d+]]
+// CHECK: [[sw0_bb0]] = OpLabel
+// CHECK:       OpSelectionMerge [[merge1:%\d+]] None
+// CHECK:       OpSwitch [[instanceID]] {{%\d+}} 0 {{%\d+}} 1 {{%\d+}} 2
+// CHECK:       OpLabel
+// CHECK: [[x_0:%\d+]] = OpLoad %type_sampler %x_0_
+// CHECK: [[y_0:%\d+]] = OpLoad %type_2d_image %y_0_
+// CHECK: [[xy_00:%\d+]] = OpSampledImage %type_sampled_image [[y_0]] [[x_0]]
+// CHECK: [[sample0:%\d+]] = OpImageSampleImplicitLod %v4float [[xy_00]] [[texCoord]] None
+// CHECK:       OpBranch [[merge1]]
+// CHECK:       OpLabel
+// CHECK:       OpLoad %type_sampler %x_0_
+// CHECK:       OpLoad %type_2d_image %y_1_
+// CHECK:       OpSampledImage %type_sampled_image
+// CHECK:       OpImageSampleImplicitLod %v4float
+// CHECK:       OpBranch [[merge1]]
+// CHECK:       OpLabel
+// CHECK:       OpLoad %type_sampler %x_0_
+// CHECK:       OpLoad %type_2d_image %y_2_
+// CHECK:       OpSampledImage %type_sampled_image
+// CHECK:       OpImageSampleImplicitLod %v4float
+// CHECK:       OpBranch [[merge1]]
+// CHECK: [[default1:%\d+]] = OpLabel
+// CHECK:       OpBranch [[merge1]]
+// CHECK: [[merge1]] = OpLabel
+// CHECK:       OpPhi %v4float [[sample0]] {{%\d+}} {{%\d+}} {{%\d+}} {{%\d+}} {{%\d+}} {{%\d+}} [[default1]]
+// CHECK:       OpBranch [[merge0]]
+
+// CHECK: [[sw0_bb1]] = OpLabel
+// CHECK:       OpSwitch [[instanceID]]
+
+// CHECK: OpLoad %type_sampler %x_1_
+// CHECK: OpLoad %type_2d_image %y_0_
+// CHECK: OpImageSampleImplicitLod %v4float %59 [[texCoord]] None
+
+// CHECK: OpLoad %type_sampler %x_1_
+// CHECK: OpLoad %type_2d_image %y_1_
+// CHECK: OpImageSampleImplicitLod %v4float %63 [[texCoord]] None
+
+// CHECK: OpLoad %type_sampler %x_1_
+// CHECK: OpLoad %type_2d_image %y_2_
+// CHECK: OpImageSampleImplicitLod %v4float %67 [[texCoord]] None
+
+// CHECK: OpPhi %v4float
+
+// CHECK:       OpBranch [[merge0]]
+// CHECK: [[default0]] = OpLabel
+// CHECK:       OpBranch [[merge0]]
+// CHECK: [[merge0]] = OpLabel
+// CHECK: [[value:%\d+]] = OpPhi %v4float {{%\d+}} {{%\d+}} {{%\d+}} {{%\d+}} {{%\d+}} [[default0]]
+// CHECK:       OpStore %out_var_SV_TARGET [[value]]
+
+  return y[instanceID].Sample(x[instanceID % 2], texCoord);
+}
diff --git a/tools/clang/unittests/SPIRV/CodeGenSpirvTest.cpp b/tools/clang/unittests/SPIRV/CodeGenSpirvTest.cpp
index 49f12c9a86..c868a6f634 100644
--- a/tools/clang/unittests/SPIRV/CodeGenSpirvTest.cpp
+++ b/tools/clang/unittests/SPIRV/CodeGenSpirvTest.cpp
@@ -1994,6 +1994,9 @@ TEST_F(FileTest, FlattenResourceArrayBindings2Optimized) {
 TEST_F(FileTest, FlattenResourceArrayBindings3) {
   runFileTest("vk.binding.cl.flatten-arrays.example3.hlsl");
 }
+TEST_F(FileTest, FlattenResourceArrayAccessedByVarIndex) {
+  runFileTest("vk.binding.flatten-arrays.var-index.hlsl");
+}
 
 // For testing the "-auto-binding-space" command line option which specifies the
 // "default space" for resources.