Senior Notes due 2021
CUSIP No. 55336V BG4
UNLESS THIS CERTIFICATE IS PRESENTED BY AN AUTHORIZED REPRESENTATIVE OF THE DEPOSITORY TRUST COMPANY, A NEW YORK CORPORATION
(DTC), NEW YORK, NEW YORK, TO THE PARTNERSHIP OR ITS AGENT FOR REGISTRATION OF TRANSFER, EXCHANGE OR PAYMENT, AND ANY CERTIFICATE ISSUED IS REGISTERED IN THE NAME OF CEDE & CO. OR SUCH OTHER NAME AS IS REQUESTED BY AN AUTHORIZED
REPRESENTATIVE OF DTC (AND ANY PAYMENT IS MADE TO CEDE & CO., OR TO SUCH OTHER ENTITY AS IS REQUESTED BY AN AUTHORIZED REPRESENTATIVE OF DTC), ANY TRANSFER, PLEDGE OR OTHER USE HEREOF FOR VALUE OR OTHERWISE BY OR TO ANY PERSON IS WRONGFUL
INASMUCH AS THE REGISTERED OWNER HEREOF, CEDE & CO., HAS AN INTEREST HEREIN.
TRANSFERS OF THIS GLOBAL SECURITY SHALL BE LIMITED TO TRANSFERS IN
WHOLE, BUT NOT IN PART, TO NOMINEES OF DTC OR TO A SUCCESSOR THEREOF OR SUCH SUCCESSORS NOMINEE AND TRANSFERS OF PORTIONS OF THIS GLOBAL SECURITY SHALL BE LIMITED TO TRANSFERS MADE IN ACCORDANCE WITH THE RESTRICTIONS SET FORTH IN THE INDENTURE
REFERRED TO HEREIN.
MPLX LP, a limited partnership duly formed and existing under the laws of the State of Delaware (herein called the
Partnership, which term includes any successor Person under the Indenture hereinafter referred to), for value received, hereby promises to pay to CEDE & CO., or registered assigns, the principal sum of [●] ($[●]), or
such greater or lesser amount as indicated on the Schedule of Increases or Decreases in the Principal Amount of Securities attached hereto, on September 9, 2021, and to pay interest thereon from September 9, 2019 or from the most recent
Interest Payment Date to which interest has been paid or duly provided for, quarterly on March 9, June 9, September 9 and December 9 in each year commencing December 9, 2019, at the rate of three-month USD LIBOR (as defined
below) plus 0.900% per annum, as determined on the second London business day preceding the interest period (the Interest Determination Date), until the principal hereof is paid or made available for payment. A London business day is a
day on which dealings in deposits in U.S. dollars are transacted in the London interbank market. The interest so payable, and punctually paid or duly provided for, on any Interest Payment Date will, as provided in such Indenture, be paid to the
Person in whose name this Debt Security (or one or more Predecessor Securities) is registered at