When running a command like `DESTDIR=foo x.py install` in a completely
clean build directory, this will cause LLVM to be installed into
`DESTDIR`, which then causes the build to fail later when it attempts
to *use* those LLVM files.
// LLVM and LLD builds can produce a lot of those and hit CI limits on log size.
cfg.define("CMAKE_INSTALL_MESSAGE", "LAZY");
+ // Do not allow the user's value of DESTDIR to influence where
+ // LLVM will install itself. LLVM must always be installed in our
+ // own build directories.
+ cfg.env("DESTDIR", "");
+
if builder.config.ninja {
cfg.generator("Ninja");
}