Error building with clang-cl on Windows

The following errors occur when trying to set clang-cl.exe instead of cl.exe as host compiler:

[1/39] Building CXX object source\CMakeFiles\ze_loader.dir\lib\ze_libapi.cpp.obj
FAILED: source/CMakeFiles/ze_loader.dir/lib/ze_libapi.cpp.obj 
C:\PROGRA~1\LLVM\bin\clang-cl.exe  /nologo -TP -DL0_LOADER_VERSION=\"1\" -DL0_VALIDATION_LAYER_SUPPORTED_VERSION=\"1\" -Dze_loader_EXPORTS -ID:\a\llvm\llvm\build\tools\sycl\plugins\level_zero\level_zero\level_zero_loader\include -ID:\a\llvm\llvm\build\tools\sycl\plugins\level_zero\level_zero\level_zero_loader\source\wrapper\include -ID:\a\llvm\llvm\build\tools\sycl\plugins\level_zero\level_zero\level_zero_loader -ID:\a\llvm\llvm\build\tools\sycl\plugins\level_zero\level_zero\level_zero_loader\source\inc /DWIN32 /D_WINDOWS /W3 /GR /EHsc /guard:cf /Qspectre /WX /W3 /wd4996 /MP /MT /O2 /Ob2 /DNDEBUG /Zi -std:c++14 /showIncludes /Fosource\CMakeFiles\ze_loader.dir\lib\ze_libapi.cpp.obj /Fdsource\CMakeFiles\ze_loader.dir\ -c -- D:\a\llvm\llvm\build\tools\sycl\plugins\level_zero\level_zero\level_zero_loader\source\lib\ze_libapi.cpp
clang-cl: error: argument unused during compilation: '/Qspectre' [-Werror,-Wunused-command-line-argument]
clang-cl: error: argument unused during compilation: '/MP' [-Werror,-Wunused-command-line-argument]
[2/39] Building CXX object source\CMakeFiles\ze_loader.dir\lib\zet_libapi.cpp.obj
FAILED: source/CMakeFiles/ze_loader.dir/lib/zet_libapi.cpp.obj 
C:\PROGRA~1\LLVM\bin\clang-cl.exe  /nologo -TP -DL0_LOADER_VERSION=\"1\" -DL0_VALIDATION_LAYER_SUPPORTED_VERSION=\"1\" -Dze_loader_EXPORTS -ID:\a\llvm\llvm\build\tools\sycl\plugins\level_zero\level_zero\level_zero_loader\include -ID:\a\llvm\llvm\build\tools\sycl\plugins\level_zero\level_zero\level_zero_loader\source\wrapper\include -ID:\a\llvm\llvm\build\tools\sycl\plugins\level_zero\level_zero\level_zero_loader -ID:\a\llvm\llvm\build\tools\sycl\plugins\level_zero\level_zero\level_zero_loader\source\inc /DWIN32 /D_WINDOWS /W3 /GR /EHsc /guard:cf /Qspectre /WX /W3 /wd4996 /MP /MT /O2 /Ob2 /DNDEBUG /Zi -std:c++14 /showIncludes /Fosource\CMakeFiles\ze_loader.dir\lib\zet_libapi.cpp.obj /Fdsource\CMakeFiles\ze_loader.dir\ -c -- D:\a\llvm\llvm\build\tools\sycl\plugins\level_zero\level_zero\level_zero_loader\source\lib\zet_libapi.cpp
clang-cl: error: argument unused during compilation: '/Qspectre' [-Werror,-Wunused-command-line-argument]
clang-cl: error: argument unused during compilation: '/MP' [-Werror,-Wunused-command-line-argument]
[3/39] Building RC object source\CMakeFiles\ze_loader.dir\ZeLoaderVersion.rc.res
Microsoft (R) Windows (R) Resource Compiler Version 10.0.10011.16384


Copyright (C) Microsoft Corporation.  All rights reserved.

ninja: build stopped: subcommand failed.

Start by reproducing the Windows build of the Level Zero loader with clang-cl.exe and inspect the compiler flags shown in the failure, especially /Qspectre and /MP. The work is done when the affected loader sources compile successfully with clang-cl without unused-argument errors.