diff --git a/lib/HLSL/DxilPreparePasses.cpp b/lib/HLSL/DxilPreparePasses.cpp
index c809fab2a4..6ca4a9bdf4 100644
--- a/lib/HLSL/DxilPreparePasses.cpp
+++ b/lib/HLSL/DxilPreparePasses.cpp
@@ -719,11 +719,6 @@ class DxilFinalizeModule : public ModulePass {
         if (DXIL::CompareVersions(ValMajor, ValMinor, 1, 1) <= 0) {
           patchValidation_1_1(M);
         }
-
-        // Set used masks for signature elements
-        MarkUsedSignatureElements(DM.GetEntryFunction(), DM);
-        if (DM.GetShaderModel()->IsHS())
-          MarkUsedSignatureElements(DM.GetPatchConstantFunction(), DM);
       }
 
       // Replace lifetime intrinsics if requested or necessary.
@@ -742,6 +737,28 @@ class DxilFinalizeModule : public ModulePass {
       // Remove store undef output.
       RemoveStoreUndefOutput(M, hlslOP);
 
+      if (!IsLib) {
+        // Set used masks for signature elements
+        MarkUsedSignatureElements(DM.GetEntryFunction(), DM);
+        if (DM.GetShaderModel()->IsHS())
+          MarkUsedSignatureElements(DM.GetPatchConstantFunction(), DM);
+      }
+
+      // Adding warning for pixel shader with unassigned target
+      if (DM.GetShaderModel()->IsPS()) {
+        DxilSignature &sig = DM.GetOutputSignature();
+        for (auto &Elt : sig.GetElements()) {
+          if (Elt->GetKind() == Semantic::Kind::Target &&
+              Elt->GetUsageMask() != Elt->GetColsAsMask()) {
+            dxilutil::EmitWarningOnContext(
+                M.getContext(),
+                "Declared output " + llvm::Twine(Elt->GetName()) +
+                    llvm::Twine(Elt->GetSemanticStartIndex()) +
+                    " not fully written in shader.");
+          }
+        }
+      }
+
       // Turn dx.break() conditional into global
       LowerDxBreak(M);
 
diff --git a/tools/clang/test/HLSLFileCheck/hlsl/diagnostics/warnings/unused-output-target-warning.hlsl b/tools/clang/test/HLSLFileCheck/hlsl/diagnostics/warnings/unused-output-target-warning.hlsl
new file mode 100644
index 0000000000..a0f8ee155b
--- /dev/null
+++ b/tools/clang/test/HLSLFileCheck/hlsl/diagnostics/warnings/unused-output-target-warning.hlsl
@@ -0,0 +1,17 @@
+// RUN: %dxc -T ps_6_0 %s | FileCheck -input=stderr %s
+
+// CHECK-NOT: warning: Declared output SV_Target0 not fully written in shader.
+// CHECK: warning: Declared output SV_Target1 not fully written in shader.
+// CHECK: warning: Declared output SV_Target2 not fully written in shader.
+// CHECK: warning: Declared output SV_Target3 not fully written in shader.
+
+void main(out float4 outRT0 : SV_Target0,
+    out float4 outRT1 : SV_Target1,
+    out float4 outRT2 : SV_Target2,
+    out float4 outRT3 : SV_Target3) {
+
+  outRT0 = 0.0f;
+  outRT1.x = 0.0f;
+  outRT2.zw = 0.0f;
+  // outRT3 = 0.0f;
+}