UBT / UAT - Passing preprocessor definitions


I’m building my project in several flavors, based on a C preprocessor definition.

For development, it is provided as an argument to GenerateProjects.bat (eg, sthg like GenerateProjects.bat -DEFINE FLAVOUR_X=1).
This is working fine: The definition is reflected in vcxproj, and I can add any required dependency in xxx.Build.cs (FLAVOUR_X will be reflected in GlobalDefinitions)

Now I want to run UAT with the same preprocessor option. Is there a way/How can I provide that macro to the BuildCookRun ?