After you have upgraded OS X EL Capitan Upgrade and Xcode 7, you get an error at IOS 9 SDK with Frameworks directory (by old Xcode projects).
You need to check your targets, and find at Build Phases the "Framework Search Paths" or "Library Search Paths".
If the warning is for option "-L/..." that is Library Search Paths, however if the warning is for option "-F/..." that is Framework Search Paths. You need to clear these.
Probably you will find these line there:
So you need to delete these lines.