Exhibit 5.1

December 5, 2012

Memorial Production Partners LP

1301 McKinney, Suite 2100

Houston, Texas 77010

Ladies and Gentlemen:

We have acted as special counsel to Memorial Production Partners LP, a Delaware limited partnership (the “Partnership”), in connection with the preparation and filing by the Partnership with the Securities and Exchange Commission of a Registration Statement on Form S-1, as amended (File No. 333-185051) (the “Registration Statement”), under the Securities Act of 1933, as amended (the “Act”). The Registration Statement relates to an underwritten public offering by the Partnership of up to 12,075,000 common units (including up to 1,575,000 common units subject to the Underwriters’ (as defined below) overallotment option) representing limited partnership interests in the Partnership (the “Units”) pursuant to the terms of an underwriting agreement in the form filed as an exhibit to the Registration Statement (the “Underwriting Agreement”) to be executed by the Partnership, Memorial Production Partners GP LLC and Memorial Production Operating LLC and Raymond James & Associates, Inc., Citigroup Global Markets Inc., Merrill Lynch, Pierce, Fenner & Smith Incorporated, Barclays Capital Inc., RBC Capital Markets, LLC and Wells Fargo Securities, LLC, as representatives of the underwriters named therein (the “Underwriters”). This opinion is being furnished in accordance with the requirements of Item 601(b)(5) of Regulation S-K under the Act.

We have examined originals or certified copies of such partnership records of the Partnership and other certificates and documents of officials of the Partnership or its general partner, public officials and others as we have deemed appropriate for purposes of this letter. We have assumed the genuineness of all signatures, the legal capacity of all natural persons, the authenticity of all documents submitted to us as originals, and the conformity to authentic original documents of all copies submitted to us as conformed, certified or reproduced copies. We have also assumed that, upon sale and delivery, the certificates for the Units will conform to the specimen thereof included as an exhibit to the partnership agreement of the Partnership filed as an exhibit to the Registration Statement and will have been duly countersigned by the transfer agent and duly registered by the registrar for the common units of the Partnership or, if uncertificated, valid book-entry notations for the issuance of the Units in uncertificated form will have been duly made in the register of common units of the Partnership. As to various questions

Memorial Production Partners LP

December 5, 2012

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of fact relevant to this letter, we have relied, without independent investigation, upon certificates of public officials and certificates of officers of the general partner of the Partnership, all of which we assume to be true, correct and complete.

Based upon the foregoing, and subject to the assumptions, exceptions, qualifications and limitations stated herein, we are of the opinion that, when the Underwriting Agreement has been duly executed and delivered and the Units have been issued and delivered as described in the Registration Statement in accordance with the Underwriting Agreement against payment in full of the consideration payable therefor as determined in accordance with the partnership agreement of the Partnership by the Board of Directors of the general partner of the Partnership or a duly authorized committee thereof and as contemplated by the Underwriting Agreement, the Units will be duly authorized, validly issued, fully paid and non-assessable.

The opinions and other matters in this letter are qualified in their entirety and subject to the following:

We hereby consent to the filing of this opinion as an exhibit to the Registration Statement and to the use of our name in the Prospectus forming a part of the Registration Statement under the caption “Validity of the Common Units.” In giving this consent, we do not thereby admit that we are within the category of persons whose consent is required under Section 7 of the Act and the rules and regulations thereunder.