diff --git a/lib/Transforms/IPO/PassManagerBuilder.cpp b/lib/Transforms/IPO/PassManagerBuilder.cpp
index 0495340dc6..118f3c6fcc 100644
--- a/lib/Transforms/IPO/PassManagerBuilder.cpp
+++ b/lib/Transforms/IPO/PassManagerBuilder.cpp
@@ -504,6 +504,17 @@ void PassManagerBuilder::populateModulePassManager(
   }
 
   // HLSL Change Begins.
+  {
+    // Run reassociate pass again after GVN since GVN will expose more
+    // opportunities for reassociation.
+    if (HLSLEnableAggressiveReassociation) {
+      MPM.add(createReassociatePass(true)); // Reassociate expressions
+      if (EnableGVN) {
+        MPM.add(createGVNPass(DisableGVNLoadPRE)); // Remove redundancies
+      }
+    }
+  }
+
   // Use value numbering to figure out if regions are equivalent, and branch to only one.
   MPM.add(createDxilSimpleGVNEliminateRegionPass());
   // HLSL don't allow memcpy and memset.
diff --git a/tools/clang/test/HLSLFileCheck/passes/transforms/reassociate/fp-common-factor-optimization.hlsl b/tools/clang/test/HLSLFileCheck/passes/transforms/reassociate/fp-common-factor-optimization.hlsl
new file mode 100644
index 0000000000..5758d2238e
--- /dev/null
+++ b/tools/clang/test/HLSLFileCheck/passes/transforms/reassociate/fp-common-factor-optimization.hlsl
@@ -0,0 +1,69 @@
+// RUN: %dxc -T cs_6_3 -E cs_main %s -opt-enable enable-aggressive-reassociation | FileCheck %s -check-prefixes=CHECK,COMMON_FACTOR
+// RUN: %dxc -T cs_6_3 -E cs_main %s -opt-disable enable-aggressive-reassociation | FileCheck %s -check-prefixes=CHECK,NO_COMMON_FACTOR
+
+// Make sure DXC recognize the common factor and generate optimized dxils.
+
+// CHECK: [[TMP_CBUF:%.*]] = call %dx.types.Handle @dx.op.createHandle(i32 57, i8 2, i32 0, i32 10, i1 false)
+
+// CHECK: [[ELEM_1:%.*]] = call %dx.types.CBufRet.f32 @dx.op.cbufferLoadLegacy.f32(i32 59, %dx.types.Handle [[TMP_CBUF]], i32 1)
+// CHECK: [[FACTOR_SRC1:%.*]] = extractvalue %dx.types.CBufRet.f32 [[ELEM_1]], 2
+
+// CHECK: [[ELEM_0:%.*]] = call %dx.types.CBufRet.f32 @dx.op.cbufferLoadLegacy.f32(i32 59, %dx.types.Handle [[TMP_CBUF]], i32 0)
+// CHECK: [[FACTOR_SRC0:%.*]] = extractvalue %dx.types.CBufRet.f32 [[ELEM_0]], 0
+
+// COMMON_FACTOR: [[FACTOR:%.*]] = fmul fast float [[FACTOR_SRC0]], [[FACTOR_SRC1]]
+// COMMON_FACTOR: fmul fast float [[FACTOR]],
+// COMMON_FACTOR: fmul fast float [[FACTOR]],
+// COMMON_FACTOR: fmul fast float [[FACTOR]],
+
+// NO_COMMON_FACTOR: [[EXPRESSION_0:%.*]] = fmul fast float [[FACTOR_SRC1]],
+// NO_COMMON_FACTOR:                        fmul fast float [[EXPRESSION_0]], [[FACTOR_SRC0]]
+// NO_COMMON_FACTOR: [[EXPRESSION_1:%.*]] = fmul fast float [[FACTOR_SRC1]],
+// NO_COMMON_FACTOR:                        fmul fast float [[EXPRESSION_1]], [[FACTOR_SRC0]] 
+// NO_COMMON_FACTOR: [[EXPRESSION_2:%.*]] = fmul fast float [[FACTOR_SRC1]],
+// NO_COMMON_FACTOR:                        fmul fast float [[EXPRESSION_2]], [[FACTOR_SRC0]]
+
+
+cbuffer TemporalAAData : register ( b10 )
+{
+    float2 viewportRelativeSize ;
+    float4 outputDimensions ;
+}
+
+Texture2D < float4 > HistoryColor : register ( t2 ) ;
+SamplerState s_Linear : register ( s1 ) ;
+RWTexture1D < float3 > outColorBuffer : register ( u0 ) ;
+
+float4 Test ( in Texture2D < float4 > tex , in SamplerState linearSampler , in float2 uv )
+{
+    float2 samplePos = uv;
+    float2 texPos1 = floor ( samplePos - 0.5f ) + 0.5f ;
+
+    float2 texPos0 = texPos1 - 1 ;
+    float2 texPos3 = texPos1 + 2 ;
+    float2 texPos12 = texPos1 + samplePos;
+
+    // DXC should recognize (outputDimensions . zw * viewportRelativeSize) is a common factor.
+    texPos0 *= outputDimensions . zw * viewportRelativeSize ;
+    texPos3 *= outputDimensions . zw * viewportRelativeSize ;
+    texPos12 *= outputDimensions . zw * viewportRelativeSize ;
+
+    float4 result = 0.0f ;
+    result += tex . SampleLevel ( linearSampler , float2 ( texPos0 . x , texPos0 . y ) , 0.0f );
+    result += tex . SampleLevel ( linearSampler , float2 ( texPos12 . x , texPos0 . y ) , 0.0f );
+    result += tex . SampleLevel ( linearSampler , float2 ( texPos3 . x , texPos0 . y ) , 0.0f );
+    result += tex . SampleLevel ( linearSampler , float2 ( texPos0 . x , texPos12 . y ) , 0.0f );
+    result += tex . SampleLevel ( linearSampler , float2 ( texPos12 . x , texPos12 . y ) , 0.0f );
+    result += tex . SampleLevel ( linearSampler , float2 ( texPos3 . x , texPos12 . y ) , 0.0f );
+    result += tex . SampleLevel ( linearSampler , float2 ( texPos0 . x , texPos3 . y ) , 0.0f );
+    result += tex . SampleLevel ( linearSampler , float2 ( texPos12 . x , texPos3 . y ) , 0.0f );
+    result += tex . SampleLevel ( linearSampler , float2 ( texPos3 . x , texPos3 . y ) , 0.0f );
+    return result ;
+}
+
+[ numthreads ( 8 , 8 , 1 ) ] void cs_main ( uint3 GroupID : SV_GroupID , uint GroupIndex : SV_GroupIndex , uint3 GTID : SV_GroupThreadID , uint3 DispatchThreadID : SV_DispatchThreadID )
+{
+    uint2 pixelCoord = GTID . xy ;
+
+    outColorBuffer [ pixelCoord.x ] = Test ( HistoryColor , s_Linear , outputDimensions . zw ) . rgb;
+}
\ No newline at end of file