compiling packages with --prefix=/ but it gives path of /usr/local

[Nupur]

Dear All,

I am upgrading few packages on redhat 7 distribution. Initially I
installed the packages (glibc, gcc, binutils, module-init-tools) with
default prefix and they got installed in /usr/local.

Now, after re-installing the same packages with --prefix=/, then also
the path shown on probing( which gcc or which ld) is /usr/local.

Why is this happening?

I'll appreciate if you can help me.

Thanks and Regards,
Nupur