Reproduction steps:
1. Open a new or an existing project
2. Go to Edit > Project Settings... > Player > Other Settings and select the IL2CPP Scripting Backend
3. Import the Toolchain Win Linux x64 package
4. Build the project

Expected result: Build succeeds
Actual result: Build fails

Part of the error:
stdout:
Running il2cpp.exe in server GC mode.
Either unknown arguments were used or one or more assemblies could not be found :
PartOfName\AppData\Local\unity3d\cache\sysroots\windows-x86_64-linux-x86_64\llvm-9.0.0-1\bin\ld.lld -target x86_64-glibc2.17-linux-gnu

Reproducible with: 2019.4.17f1, 2020.1.17f1, 2020.2.2f1, 2021.1.0b1
Could not test with: 2018.4.30f1 (due to the option to build for Linux IL2CPP not being available on this version)

Notes:
- To import the Toolchain package, include this line in the manifest.json file within the project directory:
"com.unity.toolchain.win-x86_64-linux-x86_64": "0.1.17-preview"
- Linux and macOS don't have the option to name the user profile folder with a space in the name, so the issue is not reproducible on those systems