DeveloperPolicy: "Attribution of Changes" policy question

The LLVM Developer Policy currently states:
http://llvm.org/docs/DeveloperPolicy.html#attribution-of-changes

"""
don’t commit patches authored by others unless they have submitted the
patch to the project or you have been authorized to submit them on
their behalf (you work together and your company authorized you to
contribute the patches, etc.). The author should first submit them to
the relevant project’s commit list, development list, or LLVM bug
tracker component. If someone sends you a patch privately, encourage
them to submit it to the appropriate list first.
"""

I just wanted to double-check my understanding of the requirements
here when moving out-of-tree work with multiple third-party
contributors upstream. The RISC-V LLVM work committed so far has been
authored by me (copyright held by myself or our not-for-profit,
lowRISC CIC). A couple of companies are interested in contributing
further to this effort with code which includes work from other
out-of-tree sources: https://github.com/riscv/riscv-llvm/, out of tree
but under the LLVM license.

My questions are:
1) Does this policy still apply where the work has been released
publicly under the LLVM license?
2) If so, what is the precise question that needs to be asked of the
copyright holder? (in this case, UC Berkeley amongst others). Given
that they've already released code under the LLVM license, is the
intent to additionally get agreement with the LLVM patent policy?

Thanks,

Alex