I have a C++ project in Visual Studio 2008 and I'd like to be able to compile several versions from the command line, defining conditional variables (aka #define). If it were just a single file to compile I'd use something like cl /D, but this is complex enough that I would like to be able to use VS's other features like the build order etc. I've seen a similar question asked in stackoverflow and the answer was to use /p:DefineConstants="var1;var2". This doesn't seem to work with C++ though. The other problem with that answer is that it replaces the conditional variables, instead of adding to them. The vcproj files for C++ look quite different. If msbuild (or vsbuild) had a way to change Configurations/Tool[name="VCCLCompilerTool"] we'd be golden. But I haven't found such an option. The vcproj files are under source control so I'd rather not have a script mess with them. I've considered doubling the number of configurations (one with the #define, one without). That'd be annoying, and I'm especially unhappy with having to modify these configurations in tandem every time I need to modify anything there. A previous similar question found no solution. I'm hoping that has changed since? How would you go about building those variants (with and without define) from the command line? Thanks!