UNITED STATES SECURITIES AND EXCHANGE COMMISSION

Washington, D.C. 20549

SCHEDULE 13D

Under the Securities Exchange Act of 1934

(Amendment No. __)*

Markwest Energy Partners, L.P.

(Name of Issuer)

Common Units Representing Limited Partner Interests

 (Title of Class of Securities)

570759100

(CUSIP Number)

David Shladovsky, General Counsel

1800 Avenue of the Stars, 3^rd Floor

Los Angeles, CA 90067

Telephone (310) 282-7900

(Name, Address and Telephone Number of Person

Authorized to Receive Notices and Communications)

November 16, 2015

(Date of Event Which Requires Filing of this Statement)

If the filing person has previously filed a statement on Schedule 13G to report the acquisition that is the subject of this Schedule 13D, and is filing this schedule because of sections 240.13d-1(e), 240.13d-1(f) or 140.13d-1(g), check the following box.  ☒

The information required in the remainder of this cover page shall not be deemed to be "filed" for the purpose of Section 18 of the Securities Exchange Act of 1934 ("Act") or otherwise subject to the liabilities of that section of the Act but shall be subject to all other provisions of the Act (however, see the Notes).

CUSIP No. 50187A107 (Common Stock)

1	NAMES OF REPORTING PERSONS
	I.R.S. IDENTIFICATION NOS. OF ABOVE PERSONS (ENTITIES ONLY)
	(A) Kayne Anderson Capital Advisors, L.P. (B) Richard A. Kayne
2	CHECK THE APPROPRIATE BOX IF A MEMBER OF A GROUP			(a)	☒
				(b)	☐
3	SEC USE ONLY
4	SOURCE OF FUNDS (SEE INSTRUCTIONS)
	OO
5	CHECK BOX IF DISCLOSURE OF LEGAL PROCEEDINGS IS REQUIRED PURSUANT TO ITEM 2(D) OR 2(E)				☐
6	CITIZENSHIP OR PLACE OF ORGANIZATION
	(A) California Limited Partnership (B) United States
NUMBER OF SHARES BENEFICIALLY OWNED BY EACH REPORTING PERSON WITH		7	SOLE VOTING POWER
			(A) 0 (B) 0
		8	SHARED VOTING POWER
			(A) 11,329,819 (B) 11,329,819
		9	SOLE DISPOSITIVE POWER
			(A) 0 (B) 0
		10	SHARED DISPOSITIVE POWER
			(A) 11,421,394 (B) 11,421,394
11	AGGREGATE AMOUNT BENEFICIALLY OWNED BY EACH REPORTING PERSON
	(A) 11,421,394 (B) 11,421,394
12	CHECK BOX IF THE AGGREGATE AMOUNT IN ROW (11) EXCLUDES CERTAIN SHARES (SEE INSTRUCTIONS)				☐
13	PERCENT OF CLASS REPRESENTED BY AMOUNT IN ROW (11)
	(A) 5.77% (B) 5.77%
14	TYPE OF REPORTING PERSON
	(A) IA (B) IN

Page 2

CUSIP No. 50187A107 (Common Stock)

Item 1. Security and Issuer.

Common Units Representing Limited Partner Interests of MarkWest Energy Partners, L.P.

Item 2. Identity and Background.

(a) Kayne Anderson Capital Advisors, L.P.

(b) 1800 Avenue of the Stars, 3^rd Floor

 Los Angeles, CA 90067

(c) Registered Investment Adviser

(d) None

(e) None

(f) California

(a) Richard A. Kayne

(b) 1800 Avenue of the Stars, 3^rd Floor

Los Angeles, CA 90067

(c) Chairman of Kayne Anderson Capital Advisors, L.P.

(d) None

(e) None

(f) United States

Item 3. Source and Amount of Funds or Other Consideration.

No new purchases. Prior purchases previously reported by the Reporting Persons on Schedules 13G.

Item 4. Purpose of Transaction.

The Reporting Persons entered into a Voting Agreement with MPLX LP dated November 16, 2015 to vote in favor of its offer to purchase the Issuer.

Item 5. Interest in Securities of the Issuer.

Information is included below on each of the Reporting Persons:

(A) Kayne Anderson Capital Advisors, L.P.

(B) Richard A. Kayne

(c)Please refer to Exhibit C for transactions during the prior 60 days.

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CUSIP No. 50187A107 (Common Stock)

(A)Kayne Anderson Capital Advisors, L.P. is the managing member of an affiliated investment adviser to certain investment companies registered under the Investment Company Act of 1940, the general partner of limited partnerships, and investment adviser (or managing member of such adviser) to separately managed accounts each holding shares of the Issuer as reported herein. Such investment companies, limited partnerships and separately managed accounts have the right to receive all dividends from, and the proceeds from the sale of, the securities held in their respective accounts.  The interest of any one such person does not exceed 5% of the class of securities.

(B)Richard A. Kayne is the controlling shareholder of the corporate owner of Kayne Anderson Investment Management, Inc., the general partner of Kayne Anderson Capital Advisors, L.P. Mr. Kayne is also a limited partner of each of the limited partnerships and a shareholder of the registered investment companies.  Mr. Kayne disclaims beneficial ownership of the units reported, except those units held by him or attributable to him by virtue of his limited partnership interests in the limited partnerships, his indirect interest in the interest of Kayne Anderson Capital Advisors, L.P. in the limited partnerships, and his ownership of common stock of the registered investment companies as applicable.

(e)Not applicable for any of the Reporting Persons

Item 6. Contracts, Arrangement, Understandings or Relationships with Respect to Securities of the Issuer.

The Reporting Persons have entered into a Voting Agreement dated November 16, 2015 with MPLX LP to vote in favor of the pending acquisition of the Issuer.

Item 7. Material to be Filed as Exhibits.

Exhibit A. Joint Filing Agreement between Reporting Persons

Exhibit B. Voting Agreement dated November 16, 2015 between the Reporting Persons and MPLX LP.

Exhibit C. Transactions by the Reporting Persons during the prior 60 days.

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CUSIP No. 50187A107 (Common Stock)

SIGNATURES

After reasonable inquiry and to the best of my knowledge and belief, I certify that the information set forth in this statement is true, complete and correct.

Dated:   November 17, 2015

KAYNE ANDERSON CAPITAL ADVISORS, L.P.

By Kayne Anderson Investment Management, Inc.,

Its General Partner

By:/s/ David J. Shladovsky

Name: David J. Shladovsky

Title:General Counsel

By:/s/ Richard Kayne

Name: Richard Kayne

Page 5

Exhibit A

Joint Filing Agreement Pursuant to Rule 13d-1

This agreement is made pursuant to Rule 13d-l(k)(1) under the Securities and Exchange Act of 1934, as amended (the “Act”) by and among the parties listed below, each referenced to herein as a “Joint Filer.”  The Joint Filers agree that a statement of beneficial ownership as required by Sections 13(g) or 13(d) of the Act and the Rules thereunder may be filed on each of their behalf on Schedule 13G or Schedule 13D, as appropriate, and that said joint filing may thereafter be amended by further joint filings.  The Joint Filers state that they each satisfy the requirements for making a joint filing under Rule 13d-1.

Date:  November 17, 2015

Kayne Anderson Capital Advisors, L.P.

By: Kayne Anderson Investment Management, Inc., its General Partner

By: /s/ David J. Shladovsky

Name: David J. Shladovsky

Title:  General Counsel

By: /s/ Richard A. Kayne

Name: Richard A. Kayne

Title:

Exhibit B

VOTING AGREEMENT

This VOTING AGREEMENT (this "Agreement"), dated as of November 16, 2015, is entered into by and among MPLX LP, a Delaware limited partnership ("Parent"), MPLX GP LLC, a Delaware limited liability company and the general partner of Parent ("Parent GP"), and Sapphire Holdco LLC, a Delaware limited liability company and a wholly owned subsidiary of Parent ("Merger Sub" and, with Parent and Parent GP, the "Parent Entities"), and each of the Persons set forth on Schedule A hereto (each, a "Unitholder"), as investment adviser, manager or general partner on behalf of various record and beneficial owners. All terms used but not otherwise defined in this Agreement shall have the respective meanings ascribed to such terms in the Merger Agreement (as defined below).

WHEREAS, as of the date hereof, each Unitholder is the discretionary investment adviser, manager or general partner with respect to various record and beneficial owners (as defined in Rule 13d-3 under the Exchange Act) that own the aggregate number of Common Units set forth opposite such Unitholder's name on Schedule A (all such units set forth on Schedule A next to the Unitholder's name specify those units held as of October 5, 2015 (and not sold before the date of this Agreement), which is the record date for holders of Common Units entitled to vote on the transactions contemplated by the Merger Agreement and is referred to as the "Record Date") (all such units being referred to herein as the "Subject Units"); and

WHEREAS, the Parent Entities, Marathon Petroleum Corporation, a Delaware corporation and the ultimate parent of Parent GP ("MPC"), and MarkWest Energy Partners, L.P., a Delaware limited partnership (the "Partnership"), have entered into an Agreement and Plan of Merger, dated July 11, 2015, as amended on November 10, 2015 (as it may be further amended pursuant to the terms thereof, including pursuant to the Amendment (as defined below), the "Merger Agreement"), which provides, among other things, for the merger of Merger Sub with and into the Partnership, upon the terms and subject to the conditions set forth therein (the "Merger") in accordance with the DRULPA, whereby each issued and outstanding Common Unit will be converted into the right to receive the consideration set forth in the Merger Agreement;

WHEREAS, concurrently with the execution and delivery hereof, the Parent Entities, MPC and the Partnership are entering into Amendment No. 2 to the Agreement and Plan of Merger (the "Amendment"), providing for an Exchange Ratio of 1.09 Parent Units and cash in an amount of $6.20 per Common Unit (the "Specified Consideration");

NOW, THEREFORE, in consideration of the foregoing and the respective representations, warranties, covenants and agreements set forth below and for other good and valuable consideration, the receipt and sufficiency of which are hereby acknowledged, the parties hereto, intending to be legally bound, do hereby agree as follows:

ARTICLE I

AGREEMENT TO VOTE

1.1         Agreement to Vote. Subject to the terms of this Agreement, and so long as the Unitholders remain entitled to receive not less than the Specified Consideration, each Unitholder hereby irrevocably and unconditionally agrees that, until the Termination Date with respect to such Unitholder, at any annual or special meeting of the unitholders of the Partnership, however called, including any adjournment or postponement thereof, and in connection with any action proposed to be taken by written consent of the unitholders of the Partnership, such Unitholder shall, in each case to the fullest extent that such Unitholder's Subject Units are entitled to vote thereon, and unless otherwise directed in writing by Parent: (a) appear at each such meeting or otherwise cause all such Subject Units to be counted as present thereat for purposes of determining a quorum; and (b) vote (or cause to be voted), or deliver (or cause to be delivered) a written consent with respect to, all of its Subject Units (i) in favor of the (A) approval of the Merger Agreement, the Merger and the other transactions contemplated by the Merger Agreement, and, (B) without limitation of the preceding clause (A), approval of any proposal to adjourn or postpone the Partnership Unitholders Meeting to a later date ifthere are not sufficient votes for approval and adoption of the Merger Agreement on the date on which the Partnership Unitholders Meeting is held; and (ii) against any Alternative Proposal and against any other action, agreement or transaction involving the Partnership that is intended, or would reasonably be expected, to prevent, impede, interfere with, delay, postpone, discourage or otherwise impair the consummation of the Merger or the other transactions contemplated by the Merger Agreement; and (iii) against any other action or agreement that would result in a breach of any obligation of the Partnership in the Merger Agreement. Each Unitholder shall retain at all times the right to vote the Subject Units in such Unitholder's sole discretion, and without any other limitation, on any matters other than those set forth in this Section 1.1 that are at any time or from time to time presented for consideration to the Partnership'S unitholders generally.

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ARTICLE II 

REPRESENTATIONS AND WARRANTIES OF THE UNITHOLDERS

Each Unitholder represents and warrants, on its own account with respect to the Subject Units, to the Parent Entities as to such Unitholder on a several basis, that:

2.1Authorization; Binding Agreement. Such Unitholder is duly organized andvalidly existing in good standing under the Laws of the jurisdiction in which it is incorporated or constituted and the consummation of the transactions contemplated hereby are within such Unitholder's entity powers and have been duly authorized by all necessary entity actions on the part of such Unitholder, and such Unitholder has full power and authority to execute, deliver and perform this Agreement and to consummate the transactions contemplated hereby. This Agreement has been duly and validly executed and delivered by such Unitholder and constitutes a valid and binding obligation of such Unitholder enforceable against such Unitholder in accordance with its terms, subject to the effects of bankruptcy, insolvency, fraudulent conveyance, reorganization, moratorium and other similar Laws relating to or affecting creditors' rights generally and general equitable principles (whether considered in a proceeding in equity or at law).

2.2Non-Contravention. Neither the execution and delivery of this Agreement bysuch Unitholder nor the consummation by such Unitholder of the transactions contemplated hereby, nor compliance by such Unitholder with any of the terms or provisions ofthis Agreement, will (i) conflict with or violate any provision of the certificate of incorporation or bylaws (or other similar governing documents), (ii) (x) violate any Law,judgment, writ or injunction of any Governmental Authority applicable to such Unitholder or any of their respective properties or assets, or (y) violate, conflict with, result in the loss of any benefit under, constitute a default (or an event which, with notice or lapse of time, or both, would constitute a default) under, result in the termination of or a right of termination or cancellation under, accelerate the performance required by, or result in the creation of any Lien upon any of the respective properties or assets of, such Unitholder under, any of the terms, conditions or provisions of any loan or credit agreement, debenture, note, bond, mortgage, indenture, deed of trust, license, lease, contract or other agreement, instrument or obligation, to which such Unitholder is a party, or by which they or any of their respective properties or assets may be bound or affected or (iii) result in the exercisability of any right to purchase or acquire any asset of such Unitholder, except, in the case of clauses (ii)(x), (ii)(y) and (iii), for such violations, conflicts, losses, defaults, terminations, cancellations, accelerations, Liens, purchases or acquisitions as, individually or in the aggregate, would not prevent or materially impair the consummation of the transactions contemplated hereby.

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2.3Ownership of Subject Units; Total Units. Such Unitholder is the is thediscretionary investment adviser, manager or general partner with respect to various record and beneficial owners (as defined in Rule 13d-3 under the Exchange Act) of all such Unitholder's Subject Units. The respective owners of the Subject Units for which the Unitholder is the investment adviser, manager or general partner has good and marketable title to all such Subject Units free and clear of any Liens, except for any such Lien that may be imposed pursuant to (i)this Agreement, (ii) the Partnership Agreement, (iii) any applicable restrictions on transfer under the Securities Act or any state securities law, or (iv) any leverage transactions pursuant to which the Subject Units serve as collateral (collectively, "Permitted Liens"). The Common Units listed on Schedule A opposite such Unitholder's name constitute all ofthe Common Units beneficially owned as of the Record Date by the respective owners of the Subject Units for which the Unitholder is the investment adviser or general partner.

2.4Voting Power. Such Unitholder has full voting power with respect to all suchUnitholder's Subject Units, and full power of disposition, full power to issue instructions with respect to the matters set forth herein and full power to agree to all of the matters set forth in this Agreement, in each case with respect to all such Unitholder's Subject Units. None of such Unitholder's Subject Units are subject to any unitholders' agreement, proxy, voting trust or other agreement or arrangement with respect to the voting of such Subject Units, except as provided hereunder.

2.5Absence of Litigation. With respect to such Unitholder, as ofthe date hereof,there is no Proceeding pending against, or, to the actual knowledge of such Unitholder, threatened in writing against such Unitholder or any of such Unitholder's properties or assets (including any Subject Units beneficially owned by such Unitholder) before or by any Governmental Authority that could reasonably be expected to prevent or materially delay or impair the consummation by such Unitholder of the transactions contemplated by this Agreement or otherwise materially impair such Unitholder's ability to perform its obligations hereunder.

2.6Brokers. No broker, finder, financial advisor, investment banker or other Personis entitled to any brokerage, finder's, financial advisor's or other similar fee or commission from the Parent Entities or the Partnership in connection with the transactions contemplated hereby based upon arrangements made by or on behalf of such Unitholder.

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ARTICLE III

REPRESENTATIONS AND WARRANTIES OF THE PARENT ENTITIES

The Parent Entities represent and warrant to the Unitholders that:

3.1Organization and Qualification. Each of the Parent Entities is a duly organizedand validly existing entity in good standing under the Laws of the jurisdiction of its organization. All of the issued and outstanding capital stock of Merger Sub is owned directly or indirectly by Parent.

3.2Authority for this Agreement. Each of the Parent Entities has all requisite entitypower and authority to execute, deliver and perform its obligations under this Agreement and to consummate the transactions contemplated hereby. The execution and delivery ofthis Agreement by the Parent Entities have been duly and validly authorized by all necessary entity action on the part of each of the Parent Entities, and no other entity proceedings on the part of the Parent Entities are necessary to authorize this Agreement. This Agreement has been duly and validly executed and delivered by the Parent Entities and, assuming the due authorization, execution and delivery by the Unitholders, constitutes a legal, valid and binding obligation of each of the Parent Entities, enforceable against each of the Parent Entities in accordance with its terms, except as enforceability may be limited by bankruptcy Laws, other similar Laws affecting creditors' rights and general principles of equity affecting the availability of specific performance and other equitable remedies.

ARTICLE IV

MISCELLANEOUS

4.1         Documentation and Information. Such Unitholder shall not make any public announcement regarding this Agreement and the transactions contemplated hereby without the prior written consent of Parent (such consent not to be unreasonably withheld, conditioned or delayed), except as may be required by applicable Law (provided that reasonable notice of any such disclosure will be provided to Parent). Parent acknowledges it has been advised by each Unitholder of an obligation and intent of that Unitholder to file a Schedule 13D with the SEC with respect to the Unitholder's obligations under this Agreement, and Parent consents to that filing. Such Unitholder consents to and hereby authorizes the Parent Entities and the Partnership to publish and disclose in all documents and schedules filed with the SEC or other Governmental Authority or applicable securities exchange, to the extent Parent determines such filing is required by applicable Law or regulation, and any press release or other disclosure document that the Parent Entities reasonably determine to be necessary or advisable in connection with the Merger and any other transactions contemplated by the Merger Agreement, such Unitholder's identity and ownership of the Subject Units, the existence of this Agreement and the nature of such Unitholder's commitments and obligations under this Agreement, and such Unitholder acknowledges that the Parent Entities and the Partnership may, in their respective sole discretion, file this Agreement or a form hereof with the SEC or any other Governrnental Authority or securities exchange. For the avoidance of doubt, no consent of the Unitholder shall be required to file and accurately describe contracts to which any Unitholder is a party or is otherwise referenced therein in compliance with Parent's reporting obligations under the Securities Exchange Act of 1934. Such Unitholder agrees to promptly give Parent and the Partnership any information it may reasonably require for the preparation of any such disclosure documents, and such Unitholder agrees to promptly notify Parent and the Partnership, as applicable, of any required corrections with respect to any written information supplied by such Unitholder specifically for use in any such disclosure document, if and to the extent that any such information shall have become false or misleading in any material respect.

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4.2          Notices. Any and all notices or other communications or deliveries required or permitted to be provided hereunder will be in writing and sent by facsimile, by electronic mail, by nationally recognized overnight courier service or by registered mail and will be deemed given and effective on the earliest of (a) the date of transmission, if such notice or communication is delivered via electronic mail at the email address specified in Section 8.9 of the Merger Agreement or facsimile at the facsimile telephone number specified in Section 8.9 of the Merger Agreement, in either case, prior to 5:00 p.m. (New York City time) on a Business Day and, in each case, a copy is sent on such Business Day by nationally recognized overnight courier service, (b) the Business Day after the date of transmission, if such notice or communication is delivered via electronic mail at the email address specified in Section 8.9 of the Merger Agreement or facsimile at the facsimile telephone number specified in Section 8.9 of the Merger Agreement, in each case, later than 5:00 p.m. (New York City time) on any date and earlier than 12 midnight (New York City time) on the following date and a copy is sent no later than such date by nationally recognized overnight courier service, (c) when received, if sent by nationally recognized overnight courier service (other than in the cases of clauses (a) and (b) above), or (d) upon actual receipt by the party to whom such notice is required to be given if sent by registered mail. The address for such notices and communications will be as set forth (i) if to any Parent Entity, to the address or facsimile number set forth in Section 8.9 of the Merger Agreement and (ii) if to a Unitholder, to such Unitholder's address or facsimile number set forth on a signature page hereto, or to such other address or facsimile number as such party may hereafter specify for the purpose by notice to each other party hereto.

4.3Termination. This Agreement shall terminate automatically with respect to aUnitholder, without any notice or other action by any Person, upon the first to occur of (a) the valid termination of the Merger Agreement in accordance with its terms, (b) the Effective Time,  (c) the entry without the prior written consent of such Unitholder into any amendment or modification to the Merger Agreement or any waiver of any of the Partnership's rights under the Merger Agreement, in each case, that results in a decrease in the Exchange Ratio or Cash Consideration (in each case, as defined in the Merger Agreement on the date hereof), or (d) the mutual written consent of Parent and such Unitholder (the date of termination with respect to any Unitholder being referred to herein as the "Termination Date"). Upon termination of this Agreement, no party shall have any further obligations or liabilities under this  Agreement; provided, however that (x) nothing set forth in this Section 4.3 shall relieve any party from liability for any breach of this Agreement prior to termination hereof and (y) the provisions of this Article IV shall survive any termination of this Agreement.

4.4Amendments and Waivers. Any provision of this Agreement may be amendedor waived if such amendment or waiver is in writing and is signed, in the case of an amendment, by each party to this Agreement or, in the case of a waiver, by each party against whom the waiver is to be effective. No failure or delay by any party in exercising any right hereunder will operate as a waiver thereof nor will any single or partial exercise thereof preclude any other or further exercise thereof or the exercise of any other right.

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4.5Expenses. All fees and expenses incurred in connection herewith and the transactions contemplated hereby shall be paid by the party incurring such fees and expenses, whether or not the Merger is consummated.

4.6Assignment. Neither this Agreement nor any of the rights, interests or obligations hereunder may be assigned, in whole or in part, by operation of Law or otherwise, by any of the parties without the prior written consent of the other parties, except that Merger Sub may assign, in its sole discretion, any of or all its rights, interests and obligations under this Agreement to any wholly owned Subsidiary of Parent, but no such assignment will relieve Parent, Parent GP or Merger Sub of any of its obligations hereunder. Subject to the preceding sentence, this Agreement will be binding upon, inure to the benefit of, and be enforceable by, the parties hereto and their respective successors and permitted assigns. Any purported assignment not permitted under this Section 4.6 will be null and void.

4.7Counterparts. This Agreement may be executed in counterparts (each of which will be deemed to be an original but all of which taken together will constitute one and the same agreement) and will become effective when one or more counterparts have been signed by each of the parties and delivered to the other parties.

4.8Entire Agreement; No Third-Party Beneficiaries. This Agreement, together with Schedule A, and the other documents and certificates delivered pursuant hereto, (a)constitute the entire agreement, and supersede all other prior agreements and understandings, both written and oral, among the parties with respect to the subject matter of this Agreement and thereof and (b) will not confer upon any Person other than the parties hereto any rights (including third-party beneficiary rights or otherwise) or remedies hereunder.

4.9Governing Law; Jurisdiction; Waiver of Jury Trial.

(a)This Agreement will be governed by, and construed in accordance with, the laws of the State of Delaware, applicable to contracts executed in and to be performed entirely within that State.

(b)Each of the parties hereto irrevocably agrees that any legal action or proceeding with respect to this Agreement and the rights and obligations arising hereunder, or for recognition and enforcement of any judgment in respect of this Agreement and the rights and obligations arising hereunder brought by the other party hereto or its successors or assigns, will be brought and determined exclusively in the Delaware Court of Chancery and any state appellate court therefrom within the State of Delaware (or, ifthe Delaware Court of Chancery declines to accept jurisdiction over a particular matter, any state or federal court within the State of Delaware). Each of the parties hereto hereby irrevocably submits with regard to any such action or proceeding for itself and in respect of its property, generally and unconditionally, to the personal jurisdiction of the aforesaid courts and agrees that it will not bring any action relating to this Agreement or any of the transactions contemplated by this Agreement in any court other than the aforesaid courts. Each of the parties hereto hereby irrevocably waives, and agrees not to assert as a defense, counterclaim or otherwise, in any action or proceeding with respect to this Agreement, (i) any claim that it is not personally subject to the jurisdiction ofthe above named courts for any reason, (ii) any claim that it or its property is exempt or immune from the jurisdiction of any such court or from any legal process commenced in such courts (whether through service of notice, attachment prior to judgment, attachment in aid of execution of judgment, execution of judgment or otherwise) and (iii) to the fullest extent permitted by the applicable Law, any claim that (x) the suit, action or proceeding in such court is brought in an inconvenient forum, (y) the venue of such suit, action or proceeding is improper or (z) this Agreement, or the subject matter hereof, may not be enforced in or by such courts. The parties hereto further agree that the mailing by certified or registered mail, return receipt requested, (i) if to any Parent Entity, to the address or facsimile number set forth in Section 8.9 of the Merger Agreement and (ii) if to a Unitholder, to such Unitholder's address set forth on a signature page hereto, or to such other address as such party may hereafter specify for the purpose by notice to each other party hereto, of any process required by any such court will constitute valid and lawful service of process against them, without necessity for service by any other means provided by statute or rule of court.

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(c)         EACH PARTY HEREBY IRREVOCABLY WAIVES ALL RIGHT TO TRIAL BY JURY IN ANY ACTION, PROCEEDING OR COUNTERCLAIM (WHETHER BASED ON CONTRACT, TORT OR OTHERWISE) ARISING OUT OF OR RELATING TO THIS AGREEMENT OR THE TRANSACTIONS CONTEMPLATED HEREBY OR THE ACTIONS OF ANY PARTY IN THE NEGOTIATION, ADMINISTRATION, PERFORMANCE AND ENFORCEMENT OF THIS AGREEMENT AND THE TRANSACTIONS CONTEMPLATED BY THIS AGREEMENT.

4.10       Speciflc Enforcement. The parties agree that irreparable damage would occur and that the parties would not have any adequate remedy at law in the event that any of the provisions of this Agreement were not performed in accordance with their specific terms or were otherwise breached and it is accordingly agreed that the parties will be entitled to an injunction or injunctions to prevent breaches of this Agreement and to enforce specifically the terms and provisions of this Agreement, in each case, in accordance with this Section 4.10 in the Delaware Court of Chancery or any federal court sitting in the State of Delaware, this being in addition to any other remedy to which they are entitled at law or in equity. Each of the parties agrees that it will not oppose the granting of an injunction, specific performance and other equitable relief as provided herein on the basis that (x) either party has an adequate remedy at law or (y) an award of specific performance is not an appropriate remedy for any reason at law or equity. Each party further agrees that no party will be required to obtain, furnish or post any bond or similar instrument in connection with or as a condition to obtaining any remedy referred to in this Section 4.10, and each party irrevocably waives any right it may have to require the obtaining, furnishing or posting of any such bond or similar instrument.

4.11        Severability. If any term or other provision of this Agreement is determined by a court of competent jurisdiction to be invalid, illegal or incapable of being enforced by any rule of Law or public policy, all other terms, provisions and conditions of this Agreement will nevertheless remain in full force and effect. Upon such determination that any term or other provision is invalid, illegal or incapable of being enforced, the parties hereto will negotiate in good faith to modify this Agreement so as to effect the original intent of the parties as closely as possible to the fullest extent permitted by Applicable Law in an acceptable manner to the end that the transactions contemplated hereby are fulfilled to the extent possible.

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4.12Interpretation.

(a)         The headings contained in this Agreement are for reference purposes only and will not affect in any way the meaning or interpretation of this Agreement. Whenever the words "include," "includes" or "including" are used in this Agreement, they will be deemed to be followed by the words "without limitation." The words "hereof," "herein" and "hereunder" and words of similar import when used in this Agreement will refer to this Agreement as a whole and not to any particular provision of this Agreement. All terms defined in this Agreement will have the defined meanings when used in any certificate or other document made or delivered pursuant hereto unless otherwise defined therein. The definitions contained in this Agreement are applicable to the singular as well as the plural forms of such terms and to the masculine as well as to the feminine and neuter genders of such term. Any agreement, instrument or statute defined or referred to herein or in any agreement or instrument that is referred to herein means such agreement, instrument or statute as from time to time amended, modified or supplemented, including (in the case of agreements or instruments) by waiver or consent and (in the case of statutes) by succession of comparable successor statutes and references to all attachments thereto and instruments incorporated therein. References to a Person are also to its permitted successors and assigns.

(b)          The parties hereto have participated jointly in the negotiation and drafting of this Agreement with the assistance of counsel and other advisors and, in the event an ambiguity or question of intent or interpretation arises, this Agreement will be construed as jointly drafted by the parties hereto and no presumption or burden of proof will arise favoring or disfavoring any party by virtue of the authorship of any provision of this Agreement or interim drafts of this Agreement.

4.13Further Assurances. Each Unitholder will execute and deliver, or cause to beexecuted and delivered, all further documents and instruments and use its reasonable best efforts to take, or cause to be taken, all actions and to do, or cause to be done, all things necessary, proper or advisable under applicable Laws and regulations, to perform its obligations under this Agreement.

4.14Unitholder Obligation Several and Not Joint. The obligations of eachUnitholder hereunder shall be several and not joint, and no Unitholder shall be liable for any breach of the terms ofthis Agreement by any other Unitholder.

[Remainder of Page Intentionally Left Blank. Signature Pages Follow.]

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The parties are executing this Agreement on the date set forth in the introductory clause.

PARENT:
MPLX LP
By:	MPLX GP LLC,
	its general partner
By:	/s/ G.R. Heminger
Name:	G.R. Heminger
Title:	Chairman and Chief Executive Officer
PARENT GP:
MPLX GP LLC
By:	/s/ G.R. Heminger
Name:	G.R. Heminger
Title:	Chairman and Chief Executive Officer
MERGER SUB:
SAPPHIRE HOLDCO LLC
By:	/s/ P.K.M. Beall
Name:	P.K.M. Beall
Title:	President

{Signature Page to Voting Agreement]

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UNITHOLDER
KAYNE ANDERSON CAPITAL ADVISORS, L.P., as investment adviser, manager or general partner
By:	/s/ David Shladovsky
Name:	David Shladovsky
Title:	General Counsel
UNITHOLDER
KA FUND ADVISORS, LLC, as investment adviser, manager or general partner
By:	/s/ James Baker
Name:	James Baker
Title:	Managing Director

[Signature Page to Voting Agreement]

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Schedule A

Name of Unitholder; Address	Number of Common Units
Kayne Anderson Capital Advisors, L.P.	2,792,961
1800 Avenue of the Stars, 3rd Floor
Los Angeles, CA  90067
E-mail address:
dshladovsky@kaynecapita1.com and
jbaker@kaynecapital.com
KA Fund Advisors, LLC	8,344,758
811 Main Street, 14th Floor
Houston, TX  77002
dshladovsky@kaynecapita1.com and
jbaker@kaynecapital.com

Schedule A

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Exhibit C

The following table sets forth all transactions with respect to the units effected in the last sixty days by the Reporting Persons, inclusive of any transactions effected through 4:00 p.m., eastern time, on November 16, 2015.  All such transactions were purchases of units effected in the open market.  The per unit prices noted in the table below include commissions paid.

Nature of Transaction	Reporting Person	Date of Transaction	Amount of Securities	Price Per Unit ($)
Purchase of Common Units Representing Limited Partnership Interests	Kayne Anderson Capital Advisors, L.P.	9/28/2015	100,000	44.79
Sale of Common Units Representing Limited Partnership Interests	Kayne Anderson Capital Advisors, L.P.	9/28/2015	95,000	45.28
Sale of Common Units Representing Limited Partnership Interests	Kayne Anderson Capital Advisors, L.P.	9/29/2015	52,412	43.44
Purchase of Common Units Representing Limited Partnership Interests	Kayne Anderson Capital Advisors, L.P.	9/30/2015	50,000	43.25
Sale of Common Units Representing Limited Partnership Interests	Kayne Anderson Capital Advisors, L.P.	9/30/2015	100,000	43.02
Purchase of Common Units Representing Limited Partnership Interests	Kayne Anderson Capital Advisors, L.P.	10/1/2015	10,000	43.74
Purchase of Common Units Representing Limited Partnership Interests	Kayne Anderson Capital Advisors, L.P.	10/2/2015	100,000	44.32
Purchase of Common Units Representing Limited Partnership Interests	Kayne Anderson Capital Advisors, L.P.	10/6/2015	15,000	45.92
Purchase of Common Units Representing Limited Partnership Interests	Kayne Anderson Capital Advisors, L.P.	10/7/2015	34,500	46.95
Sale of Common Units Representing Limited Partnership Interests	Kayne Anderson Capital Advisors, L.P.	10/16/2015	11,950	45.98
Sale of Common Units Representing Limited Partnership Interests	Kayne Anderson Capital Advisors, L.P.	10/19/2015	9,050	45.13

Nature of Transaction	Reporting Person	Date of Transaction	Amount of Securities	Price Per Unit ($)
Sale of Common Units Representing Limited Partnership Interests	Kayne Anderson Capital Advisors, L.P.	10/20/2015	28,100	45.05
Purchase of Common Units Representing Limited Partnership Interests	Kayne Anderson Capital Advisors, L.P.	10/28/2015	10,000	40.29
Purchase of Common Units Representing Limited Partnership Interests	Kayne Anderson Capital Advisors, L.P.	10/30/2015	5,000	43.32
Purchase of Common Units Representing Limited Partnership Interests	Kayne Anderson Capital Advisors, L.P.	11/3/2015	70,500	46.41
Purchase of Common Units Representing Limited Partnership Interests	Kayne Anderson Capital Advisors, L.P.	11/4/2015	34,500	46.97
Sale of Call Options of Common Units  Representing Limited Partnership Interests	Kayne Anderson Capital Advisors, L.P.	11/5/2015	500	96.52
Purchase of Common Units Representing Limited Partnership Interests	Kayne Anderson Capital Advisors, L.P.	11/11/2015	70,000	45.36