llvm dev - Oct 2019 - Want to Build LLVM 10 (need it to build Qt 5 along with Documentation)

Hi.  I want to build LLVM myself since I want to build Qt 5 for WebAssembly and
I want to see if having the same version of LLVM installed as the one used by
EMSDK will help if I also want to build the Documentation (basically I want to
avoid a chance of conflicts between versions).  I'm using the latest version
of the EMSDK which uses LLVM 10 currently by default.  I understand that not
everyone on this mailing list knows much about WebAssembly, but my main
intention here is only to ask about building LLVM and the info I just gave is
just to let you guys know what I'm trying to do and why.

Anyway, the command I ran was:
"cmake -DCMAKE_INSTALL_PREFIX=../install -G"Visual Studio 16
2019" -Thost=x64 -A x86
-DLLVM_ENABLE_PROJECTS="clang;clang-tools-extra;lld;lldb;libcxx;libcxxabi"
-DCMAKE_BUILD-TYPE=Release -MSVC_RUNTIME_TYPE=/MT -DLLVM_TARGETS_TO_BUILD=all
-DLLVM_ENABLE_THREADS=On -DLLVM_CXX_STD="c++17"
-DLLVM_ENABLE_PEDANTIC=On
-DCMAKE_CXX_FLAGS="/std:c++17;/permissive-;/MT;/EHsc" ../llvm"

I put the error message I got in the .log file I'm attaching to this
message.  Any help is appreciated.  Thanks.  (Maybe I should also ask at the
CMake mailing list for help?).
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I was able to get it to work through the VS2019 IDE itself for now (thank God
they have built-in CMake support in VS2017 and later), but I'd still like to
know how to get it to work on the command line directly.
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