runtime: Perf tests are broken when run from project test directory

I’m trying to build and run the System.Collections perf tests. Following the instructions at https://github.com/dotnet/corefx/blob/master/Documentation/project-docs/performance-tests.md, I did a:

git clean -xdf
build -release

from the root of my repo, and then from src\System.Collections\tests\Performance did:

msbuild /t:BuildAndTest /p:Performance=true /p:ConfigurationGroup=Release /p:TargetOS=Windows_NT

and I get the error:

The application to execute does not exist: 'corefx\bin\tests\System.Collections.Performance.Tests\netcoreapp-Windows_NT-Release-x64\PerfRunner.exe'