Exhibit 5.1

Tel +713.758.2222 Fax +713.758.2346

                    , 2017

BP Midstream Partners LP

1001 Fannin St., Suite 1500

Houston, Texas 77002

Ladies and Gentlemen

We have acted as counsel to BP Midstream Partners LP, a Delaware limited partnership (the “Partnership”), in connection with the registration under the Securities Act of 1933, as amended (the “Securities Act”), of the offering and sale by the Partnership of up to an aggregate of              common units representing limited partner interests in the Partnership (the “Common Units”) and up to an additional              Common Units pursuant to the underwriters’ option to purchase additional Common Units.

We are rendering this opinion as of the time the Partnership’s Registration Statement on Form S-1 (File No. 333-                     ), as amended (the “Registration Statement”), to which this opinion is an exhibit and relating to the Common Units, becomes effective in accordance with Section 8(a) of the Securities Act. The term “Common Units” shall include any additional common units representing limited partner interests in the Partnership registered pursuant to Rule 462(b) under the Securities Act in connection with the offering contemplated by the Registration Statement.

As the basis for the opinion hereinafter expressed, we examined such statutes, including the Delaware Revised Uniform Limited Partnership Act (the “Delaware LP Act”), and the Partnership’s respective records and documents, certificates of the Partnership and public officials, and other instruments and documents as we deemed necessary or advisable for the purposes of this opinion. In such examination, we have assumed (i) the authenticity of all documents submitted to us as originals and the conformity with the original documents of all documents submitted to us as copies and (ii) that a definitive underwriting agreement in the form filed as an exhibit to the Registration Statement with respect to the sale of the Common Units will have been duly authorized and validly executed and delivered by the Partnership and the other parties thereto.

Based on the foregoing and on such legal considerations as we deem relevant, we are of the opinion that the Common Units, when issued and delivered on behalf of the Partnership against payment therefor as described in the Registration Statement, will be duly authorized, validly issued, fully paid and non-assessable.

The foregoing opinion is limited to the federal laws of the United States of America, the Constitution of the State of Delaware and the Delaware LP Act, each as interpreted by the federal courts and the courts of the State of Delaware, and we are expressing no opinion as to the effect of the laws of any other jurisdiction.

We hereby consent to the reference to us under the heading “Legal Matters” in the Registration Statement and the filing of this opinion as an exhibit to the Registration Statement. We further consent to the incorporation by reference of this letter and consent into any registration statement filed pursuant to Rule 462(b) under the Securities Act with respect to the Common Units. By giving this consent, we do not admit that we are within the category of persons whose consent is required under Section 7 of the Securities Act and the rules and regulations thereunder.

Very truly yours,