[CMake] adding a custom command with the file name as a target

[Jim Newsome]

I'd like to do something like add_custom_command, with the output file
name as a target in the generated makefile. Is there an elegant way of
doing this?

The closest I've come is:
add_executable (hello hello.c)
add_custom_command(OUTPUT hello.bin
                    COMMAND objcopy --output-format=binary hello hello.bin
                   DEPENDS hello
                   COMMENT "objcopying hello to hello.bin")
add_custom_target(bin ALL DEPENDS hello.bin)

However, the target name in the generated makefile is 'bin' rather
than 'hello.bin'. Is there a way to make 'hello.bin' itself a target
in the generated makefile?

Thanks!
-Jim