SecProbe.io

March 30, 2020
Michael J. Hennigan
President and Chief Executive Officer
MPLX LP
200 E. Hardin Street
Findlay, OH 45840
Re:MPLX LP
Registration Statement on Form S-4
Filed March 20, 2020
File No. 333-237317
Dear Mr. Hennigan:
            We have limited our review of your registration statement to those issues we have
addressed in our comments.  In some of our comments, we may ask you to provide us with
information so we may better understand your disclosure.
            Please respond to this letter by amending your registration statement and providing the
requested information.  If you do not believe our comments apply to your facts and
circumstances or do not believe an amendment is appropriate, please tell us why in your
response.
            After reviewing any amendment to your registration statement and the information you
provide in response to these comments, we may have additional comments.
Registration Statement on Form S-4
General
1.We note that the forum selection provision in Section 16.9 of your Fifth Amended and
Restated Agreement of Limited Partnership identifies the Court of Chancery of the State
of Delaware as the exclusive forum for certain litigation, including claims, suits, actions
or proceedings "brought in a derivative manner on behalf of the Partnership."  Please
disclose whether this provision applies to actions arising under the Securities Act or
Exchange Act.  In that regard, we note that Section 27 of the Exchange Act creates
exclusive federal jurisdiction over all suits brought to enforce any duty or liability created
by the Exchange Act or the rules and regulations thereunder, and Section 22 of the
Securities Act creates concurrent jurisdiction for federal and state courts over all suits
brought to enforce any duty or liability created by the Securities Act or the rules and

 FirstName LastNameMichael J. Hennigan
 Comapany NameMPLX LP
 March 30, 2020 Page 2
 FirstName LastName
Michael J. Hennigan
MPLX LP
March 30, 2020
Page 2
regulations thereunder.  If the provision applies to Securities Act claims, please also revise
your prospectus to state that there is uncertainty as to whether a court would enforce such
provision and that investors cannot waive compliance with the federal securities laws and
the rules and regulations thereunder.  If this provision does not apply to actions arising
under the Securities Act or Exchange Act, please tell us how you will inform investors in
future filings that the provision does not apply to any actions arising under the Securities
Act or Exchange Act.
            We remind you that the company and its management are responsible for the accuracy
and adequacy of their disclosures, notwithstanding any review, comments, action or absence of
action by the staff.
            Refer to Rules 460 and 461 regarding requests for acceleration.  Please allow adequate
time for us to review any amendment prior to the requested effective date of the registration
statement.
            Please contact Karina Dorin, Staff Attorney, at (202) 551-3763 or Lauren Nguyen, Legal
Branch Chief, at (202) 551-3642 with any  questions.
Sincerely,
Division of Corporation Finance
Office of Energy & Transportation