diff --git a/clang/include/clang/Basic/DiagnosticDriverKinds.td b/clang/include/clang/Basic/DiagnosticDriverKinds.td
--- a/clang/include/clang/Basic/DiagnosticDriverKinds.td
+++ b/clang/include/clang/Basic/DiagnosticDriverKinds.td
@@ -666,6 +666,9 @@
   "invalid profile : %0">;
 def err_drv_dxc_missing_target_profile : Error<
   "target profile option (-T) is missing">;
+def warn_drv_dxc_ignore_output_for_preprocess : Warning<
+  "'%0' ignored when not compiling">,
+  InGroup<OptionIgnored>;
 
 def err_drv_invalid_range_dxil_validator_version : Error<
   "invalid validator version : %0\n"
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
@@ -6381,6 +6381,9 @@
 class CLFlag<string name> : Option<["/", "-"], name, KIND_FLAG>,
   Group<cl_Group>, Flags<[CLOption, NoXarchOption]>;
 
+class CLDXCFlag<string name> : Option<["/", "-"], name, KIND_FLAG>,
+  Group<cl_Group>, Flags<[CLDXCOption, NoXarchOption]>;
+
 class CLCompileFlag<string name> : Option<["/", "-"], name, KIND_FLAG>,
   Group<cl_compile_Group>, Flags<[CLOption, NoXarchOption]>;
 
@@ -6393,6 +6396,9 @@
 class CLCompileJoined<string name> : Option<["/", "-"], name, KIND_JOINED>,
   Group<cl_compile_Group>, Flags<[CLOption, NoXarchOption]>;
 
+class CLDXCCompileJoined<string name> : Option<["/", "-"], name, KIND_JOINED>,
+  Group<cl_compile_Group>, Flags<[CLDXCOption, NoXarchOption]>;
+
 class CLIgnoredJoined<string name> : Option<["/", "-"], name, KIND_JOINED>,
   Group<cl_ignored_Group>, Flags<[CLOption, NoXarchOption, HelpHidden]>;
 
@@ -6662,7 +6668,7 @@
   HelpText<"Set output executable file name">,
   MetaVarName<"<file or dir/>">;
 def _SLASH_Fe_COLON : CLJoined<"Fe:">, Alias<_SLASH_Fe>;
-def _SLASH_Fi : CLCompileJoined<"Fi">,
+def _SLASH_Fi : CLDXCCompileJoined<"Fi">,
   HelpText<"Set preprocess output file name (with /P)">,
   MetaVarName<"<file>">;
 def _SLASH_Fo : CLCompileJoined<"Fo">,
@@ -6697,7 +6703,7 @@
 def _SLASH_o : CLJoinedOrSeparate<"o">,
   HelpText<"Deprecated (set output file name); use /Fe or /Fe">,
   MetaVarName<"<file or dir/>">;
-def _SLASH_P : CLFlag<"P">, HelpText<"Preprocess to file">;
+def _SLASH_P : CLDXCFlag<"P">, HelpText<"Preprocess to file">;
 def _SLASH_permissive : CLFlag<"permissive">,
   HelpText<"Enable some non conforming code to compile">;
 def _SLASH_permissive_ : CLFlag<"permissive-">,
diff --git a/clang/lib/Driver/Driver.cpp b/clang/lib/Driver/Driver.cpp
--- a/clang/lib/Driver/Driver.cpp
+++ b/clang/lib/Driver/Driver.cpp
@@ -5455,7 +5455,8 @@
 
   llvm::PrettyStackTraceString CrashInfo("Computing output path");
   // Output to a user requested destination?
-  if (AtTopLevel && !isa<DsymutilJobAction>(JA) && !isa<VerifyJobAction>(JA)) {
+  if (AtTopLevel && !isa<DsymutilJobAction>(JA) && !isa<VerifyJobAction>(JA) &&
+      !(IsDXCMode() && C.getArgs().hasArg(options::OPT__SLASH_P))) {
     if (Arg *FinalOutput = C.getArgs().getLastArg(options::OPT_o))
       return C.addResultFile(FinalOutput->getValue(), &JA);
   }
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
@@ -177,6 +177,9 @@
   }
 
   if (DAL->hasArg(options::OPT_o)) {
+    if (DAL->hasArg(options::OPT__SLASH_P))
+      getDriver().Diag(diag::warn_drv_dxc_ignore_output_for_preprocess) << "Fo";
+
     // When run the whole pipeline.
     if (!DAL->hasArg(options::OPT_emit_llvm))
       // Emit obj if write to file.
diff --git a/clang/test/Driver/dxc_P.hlsl b/clang/test/Driver/dxc_P.hlsl
new file mode 100644
--- /dev/null
+++ b/clang/test/Driver/dxc_P.hlsl
@@ -0,0 +1,16 @@
+// RUN: %clang_dxc -Tlib_6_7 -P -### %s 2>&1 | FileCheck %s
+// RUN: %clang_dxc -Tlib_6_7  -P -Fi"a.txt" -### %s 2>&1 | FileCheck %s --check-prefix=FI
+// RUN: %clang_dxc -Tlib_6_7  -Fo b.txt -P -Fi"a.txt" -### %s 2>&1 | FileCheck %s --check-prefix=WARNING
+
+// Make sure -P option flag which translated into "-E" + "-o" "dxc_P.i".
+// CHECK:"-E"
+// CHECK-SAME: "-o" "dxc_P.i"
+
+// Make sure -Fi updated -o.
+// FI:"-E"
+// FI-SAME:"-o" "a.txt"
+
+// Make sure got warning when -Fo and -P at same time.
+// WARNING: warning: 'Fo' ignored when not compiling [-Woption-ignored]
+// WARNING:"-E"
+// WARNING-SAME:"-o" "a.txt"