So there is no option in the compiler to set the clock frequency of the processor....How will that be handled? Do i need to edit the Makefile?
"How will that be handled?"
As Tamir says, that will be described in the Datasheet for the particular chip that you are using - so you will just need to write whatever code is necessary to do whatever the Datasheet tells you.
If it's possible, the chip manufacturer may provide libraries to help...
find out of your chip is a '51 type or an ARM type
Erik