diff --git a/clang/include/clang/Basic/TargetOptions.h b/clang/include/clang/Basic/TargetOptions.h
--- a/clang/include/clang/Basic/TargetOptions.h
+++ b/clang/include/clang/Basic/TargetOptions.h
@@ -113,6 +113,9 @@
 
   /// The validator version for dxil.
   std::string DxilValidatorVersion;
+
+  /// Keep the information about disable optimization for ShaderFlags.
+  bool DxcOptDisable = false;
 };
 
 } // end namespace clang
diff --git a/clang/include/clang/Driver/Options.td b/clang/include/clang/Driver/Options.td
--- a/clang/include/clang/Driver/Options.td
+++ b/clang/include/clang/Driver/Options.td
@@ -6854,6 +6854,14 @@
          "as_6_5, as_6_6, as_6_7">;
 def dxc_D : Option<["--", "/", "-"], "D", KIND_JOINED_OR_SEPARATE>,
   Group<dxc_Group>, Flags<[DXCOption, NoXarchOption]>, Alias<D>;
+def dxc_O : Option<["--", "/", "-"], "O", KIND_JOINED>,
+  Group<dxc_Group>, Flags<[DXCOption, NoXarchOption]>, Alias<O>;
+def dxc_Od : Option<["--", "/", "-"], "Od", KIND_FLAG>,
+  Group<dxc_Group>, Flags<[DXCOption, NoXarchOption]>,
+  HelpText<"Disable optimizations.">;
+def dxc_opt_disable : Flag<["-"], "dxc-opt-disable">, Group<dxc_Group>, Flags<[CC1Option]>,
+  MarshallingInfoFlag<TargetOpts<"DxcOptDisable">>,
+  HelpText<"HLSL only. This option disables all optimizations. By default optimizations are enabled.">;
 def emit_pristine_llvm : DXCFlag<"emit-pristine-llvm">,
   HelpText<"Emit pristine LLVM IR from the frontend by not running any LLVM passes at all."
            "Same as -S + -emit-llvm + -disable-llvm-passes.">;
diff --git a/clang/lib/CodeGen/CGHLSLRuntime.cpp b/clang/lib/CodeGen/CGHLSLRuntime.cpp
--- a/clang/lib/CodeGen/CGHLSLRuntime.cpp
+++ b/clang/lib/CodeGen/CGHLSLRuntime.cpp
@@ -42,6 +42,11 @@
   StringRef DxilValKey = "dx.valver";
   M.addModuleFlag(llvm::Module::ModFlagBehavior::AppendUnique, DxilValKey, Val);
 }
+void addDisableOptimizations(llvm::Module &M) {
+  StringRef Key = "dx.disable_optimizations";
+  M.addModuleFlag(llvm::Module::ModFlagBehavior::Override, Key, 1);
+}
+
 } // namespace
 
 void CGHLSLRuntime::finishCodeGen() {
@@ -49,4 +54,6 @@
 
   llvm::Module &M = CGM.getModule();
   addDxilValVersion(TargetOpts.DxilValidatorVersion, M);
+  if (TargetOpts.DxcOptDisable)
+    addDisableOptimizations(M);
 }
diff --git a/clang/lib/Driver/ToolChains/Clang.cpp b/clang/lib/Driver/ToolChains/Clang.cpp
--- a/clang/lib/Driver/ToolChains/Clang.cpp
+++ b/clang/lib/Driver/ToolChains/Clang.cpp
@@ -3482,6 +3482,8 @@
   const unsigned ForwardedArguments[] = {options::OPT_dxil_validator_version,
                                          options::OPT_D,
                                          options::OPT_S,
+                                         options::OPT_O,
+                                         options::OPT_dxc_opt_disable,
                                          options::OPT_emit_llvm,
                                          options::OPT_disable_llvm_passes,
                                          options::OPT_fnative_half_type};
diff --git a/clang/lib/Driver/ToolChains/HLSL.cpp b/clang/lib/Driver/ToolChains/HLSL.cpp
--- a/clang/lib/Driver/ToolChains/HLSL.cpp
+++ b/clang/lib/Driver/ToolChains/HLSL.cpp
@@ -158,6 +158,12 @@
       if (!isLegalValidatorVersion(ValVerStr, getDriver()))
         continue;
     }
+    if (A->getOption().getID() == options::OPT_dxc_Od) {
+      DAL->AddFlagArg(nullptr, Opts.getOption(options::OPT_dxc_opt_disable));
+      DAL->AddFlagArg(nullptr, Opts.getOption(options::OPT_O0));
+      A->claim();
+      continue;
+    }
     if (A->getOption().getID() == options::OPT_emit_pristine_llvm) {
       // Translate fcgl into -S -emit-llvm and -disable-llvm-passes.
       DAL->AddFlagArg(nullptr, Opts.getOption(options::OPT_S));
diff --git a/clang/lib/Frontend/CompilerInvocation.cpp b/clang/lib/Frontend/CompilerInvocation.cpp
--- a/clang/lib/Frontend/CompilerInvocation.cpp
+++ b/clang/lib/Frontend/CompilerInvocation.cpp
@@ -572,6 +572,9 @@
       !Args.hasArg(OPT_cl_opt_disable))
     DefaultOpt = llvm::CodeGenOpt::Default;
 
+  if (IK.getLanguage() == Language::HLSL)
+    DefaultOpt = llvm::CodeGenOpt::Aggressive;
+
   if (Arg *A = Args.getLastArg(options::OPT_O_Group)) {
     if (A->getOption().matches(options::OPT_O0))
       return llvm::CodeGenOpt::None;
diff --git a/clang/test/CodeGenHLSL/disable_opt.hlsl b/clang/test/CodeGenHLSL/disable_opt.hlsl
new file mode 100644
--- /dev/null
+++ b/clang/test/CodeGenHLSL/disable_opt.hlsl
@@ -0,0 +1,12 @@
+// RUN: %clang -cc1 -S -triple dxil-pc-shadermodel6.3-library -dxc-opt-disable -emit-llvm -xhlsl  -o - %s | FileCheck %s
+// RUN: %clang -cc1 -S -triple dxil-pc-shadermodel6.3-library -emit-llvm -xhlsl  -o - %s | FileCheck %s --check-prefix=OPT
+
+// CHECK:!"dx.disable_optimizations", i32 1}
+
+// OPT-NOT:"dx.disable_optimizations"
+
+float bar(float a, float b);
+
+float foo(float a, float b) {
+  return bar(a, b);
+}
diff --git a/clang/test/Driver/dxc_O.hlsl b/clang/test/Driver/dxc_O.hlsl
new file mode 100644
--- /dev/null
+++ b/clang/test/Driver/dxc_O.hlsl
@@ -0,0 +1,15 @@
+// RUN: %clang_dxc -fcgl -T lib_6_7 -Od foo.hlsl -### %s 2>&1 | FileCheck %s
+// RUN: %clang_dxc -fcgl -T lib_6_7 -O0 foo.hlsl -### %s 2>&1 | FileCheck %s --check-prefix=O0
+// RUN: %clang_dxc -fcgl -T lib_6_7 -O1 foo.hlsl -### %s 2>&1 | FileCheck %s --check-prefix=O1
+// RUN: %clang_dxc -fcgl -T lib_6_7 -O2 foo.hlsl -### %s 2>&1 | FileCheck %s --check-prefix=O2
+// RUN: %clang_dxc -fcgl -T lib_6_7 -O3 foo.hlsl -### %s 2>&1 | FileCheck %s --check-prefix=O3
+
+// Make sure fcgl option flag which translated into "-O0" "-dxc-opt-disable"
+// CHECK: "-O0"
+// CHECK-SAME: "-dxc-opt-disable"
+
+// Make sure O0/O1/O2/O3 is send to cc1.
+// O0: "-O0"
+// O1: "-O1"
+// O2: "-O2"
+// O3: "-O3"