Washington, D.C. 20549
 Current Report
Pursuant to Section 13 or 15(d) of The
Securities Exchange Act of 1934
Date of Report (Date of earliest event reported) January 2, 2018
(Exact name of registrant as specified in its charter)
(State or other jurisdiction
of incorporation)
(Commission File Number)
(IRS Employer
Identification No.)
200 E. Hardin Street
Findlay, Ohio
(Address of principal executive offices)
(Zip Code)
Registrant’s telephone number, including area code:
(419) 421-2414
(Former name or former address, if changed since last report.)
Check the appropriate box below if the Form 8-K filing is intended to simultaneously satisfy the filing obligation of the registrant under any of the following provisions:
Written communications pursuant to Rule 425 under the Securities Act (17 CFR 230.425)
Soliciting material pursuant to Rule 14a-12 under the Exchange Act (17 CFR 240.14a-12)
Pre-commencement communications pursuant to Rule 14d-2(b) under the Exchange Act (17 CFR 240.14d-2(b))
Pre-commencement communications pursuant to Rule 13e-4(c) under the Exchange Act (17 CFR 240.13e-4(c))
Indicate by check mark whether the registrant is an emerging growth company as defined in Rule 405 of the Securities Act of 1933 (§230.405 of this chapter) or Rule 12b-2 of the Securities Exchange Act of 1934 (§240.12b-2 of this chapter).
Emerging growth company ¨
If an emerging growth company, indicate by check mark if the registrant has elected not to use the extended transition period for complying with any new or revised financial accounting standards provided pursuant to Section 13(a) of the Exchange Act. ¨

Item 5.03
Amendments to Articles of Incorporation or Bylaws; Change in Fiscal Year.

On January 2, 2018, MPLX GP LLC, the general partner (the “General Partner”) of MPLX LP (the “Partnership”), entered into a Second Amendment (the “Amendment”) to the Third Amended and Restated Agreement of Limited Partnership of the Partnership, dated as of October 31, 2016, as amended by the Frist Amendment, dated as of February 23, 2017 (as amended, the “Partnership Agreement”), in response to changes to the Internal Revenue Code enacted by the Bipartisan Budget Act of 2015 (the “BBA”) relating to partnership audit and adjustment procedures. The Amendment makes certain revisions to the Partnership Agreement that facilitate the General Partner’s obligations as the “Partnership Representative” under the BBA and, if possible and practical, provide the General Partner with the option of maintaining the current economic balance by which the partners during a reviewed year bear the economic burden associated with any adjustments for such year.
The foregoing description of the Amendment in this Current Report does not purport to be complete and is qualified in its entirety by reference to the full text of the Amendment, a copy of which is filed as Exhibit 3.1 to this Current Report, and is incorporated herein by reference.

Item 7.01
Regulation FD Disclosure.

On January 8, 2018, MPLX LP updated its investor presentation (the “Presentation”) posted to its website at The slides attached as Exhibit 99.1 to this Current Report on Form 8-K are incorporated herein by reference. Information on or accessible through the MPLX website is not, and shall not be deemed to be, part of this Current Report on Form 8-K.

The information provided in this Item 7.01 (including Exhibit 99.1) is being furnished and shall not be deemed "filed" for the purposes of Section 18 of the Securities Exchange Act of 1934, or otherwise subject to the liabilities of that section, nor shall it be deemed incorporated by reference into any registration statement or other filing under the Securities Act of 1933, except as shall be expressly set forth by specific reference to such filing.

Item 9.01
Financial Statements and Exhibits.
(d) Exhibits.
Exhibit Number

Pursuant to the requirements of the Securities Exchange Act of 1934, the registrant has duly caused this report to be signed on its behalf by the undersigned hereunto duly authorized.
MPLX GP LLC, its General Partner
Date: January 8, 2018
/s/ Molly R. Benson
Name: Molly R. Benson
Title: Vice President, Corporate Secretary and Chief Compliance Officer