something about the memory layout and basic block alignment

I’m trying to implement something similar to the sandbox and i need to control the block alignment and the memory layout.I have already read the document and the mail list but i failed to solve it.
I know that gcc can set the alignment of the basic code blocks by compile option -falign-label=n.So is there any option similar to this in llvm?
And I know we can control the memory layout by GNU linker script while linking.For example , we can set the .text section’s address in linker script.So what should i do to control the memory layout in llvm?
Thank you