QEPM

SUMMARY

This summary highlights some of the information in this proxy statement/prospectus. It may not contain all of the information that is important to you. To understand the merger fully and for a more complete description of the terms of the merger, you should read carefully this document, the documents incorporated by reference, and the Annexes to this document, including the full text of the merger agreement included as Annex A. Please also read “Where You Can Find More Information.”

The Merger Parties’ Businesses (see page 99)

Tesoro Logistics LP

TLLP is a publicly traded Delaware limited partnership, the common units of which are listed on the NYSE under the ticker symbol “TLLP.” TLLP is a fee-based, growth oriented Delaware limited partnership formed by Tesoro Corporation (“Tesoro”) and is a leading full-service logistics company operating primarily in the western and mid-continent regions of the United States. TLLP owns and operates networks of over 3,500 miles of crude oil, refined products and natural gas pipelines and 28 crude oil and refined products truck and marine terminals that have over 9 million barrels of storage capacity. In addition, TLLP owns and operates four natural gas processing complexes and one fractionation facility. TLLP’s business operates in three segments: Gathering, Processing, and Terminalling and Transportation. TLLP introduced a new reporting segment (Processing) for the processing operations acquired in December of 2014. In addition, TLLP modified its previous Crude Oil Gathering segment to encompass all gathering operations, including the natural gas transmission operations acquired in December of 2014.

TLLP’s principal executive offices are located at 19100 Ridgewood Pkwy, San Antonio, Texas 78259, and its telephone number is (210) 626-6000.

QEP Midstream Partners, LP

QEPM is a publicly traded Delaware limited partnership. QEPM common units are listed on the NYSE under the ticker symbol “QEPM.” QEPM is a master limited partnership formed by QEP Resources, Inc. (“QEP Resources”) to own, operate, acquire and develop midstream energy assets. QEPM’s primary assets consist of ownership interests in four gathering systems and two FERC-regulated pipelines through which QEPM provides natural gas and crude oil gathering and transportation services. QEPM’s assets are located in, or are within close proximity to, the Green River Basin located in Wyoming and Colorado, the Uinta Basin located in eastern Utah, and the Williston Basin located in North Dakota. As of the year ended December 31, 2014, QEPM’s gathering systems had over 1,500 miles of pipeline. QEPM believes its customers are some of the largest natural gas producers in the Rocky Mountain region.

QEPM’s principal executive offices are located at 19100 Ridgewood Pkwy, San Antonio, Texas 78259, and its telephone number is (210) 626-6000.

Certain Relationships; Interests of Certain Persons in the Merger (see page 101)

TLLP and QEPM are currently under common control. As of December 2, 2014, QEPM was owned 98.0% by its limited partners and 2.0% by its general partner, QEPM GP. On December 2, 2014, TLLP closed the acquisition of QEP Field Services, and TLLP acquired, directly or through its wholly owned subsidiaries, QEPM’s general partner and approximately 55.8% of the limited partner interests in QEPM, consisting of 3,701,750 common units and 26,705,000 subordinated units, and 100% of the limited liability company interests of QEPM GP, which itself owns all of QEPM’s outstanding incentive distribution rights. In addition, some of the directors of QEPM GP are also executive officers or employees of Tesoro or TLLP GP, including Gregory J. Goff, Phillip M. Anderson, Keith M. Casey, Charles S. Parrish and Steven M. Sterin.

Additionally, TLLP and QEPM and their general partners have extensive and ongoing relationships with Tesoro and its affiliates. TLLP GP is a wholly owned subsidiary of Tesoro. Certain current executive officers of TLLP GP and QEPM GP are current employees of Tesoro. Much of TLLP’s total revenue is derived from Tesoro under various long-term, fee-based commercial agreements that generally include minimum volume commitments.

For information on specific contracts and arrangements between TLLP and QEPM, please see “Certain Relationships; Interests of Certain Persons in the Merger.”

Structure of the Merger and Related Transactions (see page 76)

Pursuant to the merger agreement, at the effective time of the merger, a wholly owned subsidiary of TLLP will merge with and into QEPM, with QEPM surviving the merger as an indirect, wholly owned subsidiary of TLLP, and each outstanding common unit of QEPM held by QEPM unaffiliated unitholders will be cancelled and converted into the right to receive 0.3088 TLLP common units. This merger consideration represents an 8.5% premium to the closing price of QEPM common units based on the closing prices of QEPM common units and TLLP common units on December 1, 2014, the last trading day before TLLP made its initial proposal to acquire all of QEPM common units held by the public. Relative to the respective closing prices for TLLP and QEPM common units on April 6, 2015, the day the parties entered into the merger agreement, the 0.3088 exchange ratio represents an 8.6% premium to QEPM common unitholders.

The subordinated units and incentive distribution rights of QEPM will remain outstanding through the effectiveness of the merger, as will the QEPM common units held by QEP Field Services, and none of the entities that hold these interests (all of which are affiliates of QEPM GP) will receive any consideration for the continuation of their respective limited partner interests in QEPM in connection with the merger. The QEPM general partner interest held by QEPM GP will also remain outstanding through the effectiveness of the merger, and QEPM GP will not receive any consideration for the continuation of its general partner interest in connection with the merger.

If the exchange ratio would result in a QEPM unaffiliated unitholder being entitled to receive a fraction of a TLLP common unit, then such QEPM unaffiliated unitholder will receive cash from TLLP in lieu of such fractional interest in an amount equal to such fractional interest multiplied by the average of the closing price of TLLP common units for the five trading day period ending on the third trading day immediately prior to the day upon which the merger becomes effective.

Once the merger is completed and QEPM common units held by QEPM unaffiliated unitholders are exchanged for TLLP common units (and cash in lieu of fractional units, if applicable), when distributions are declared by the general partner of TLLP and paid by TLLP, former QEPM unaffiliated common unitholders will receive distributions on their TLLP common units in accordance with TLLP’s partnership agreement. For a description of the distribution provisions of TLLP’s partnership agreement, please read “Comparison of the Rights of TLLP and QEPM Unitholders.”

As of June 8, 2015, there were 80,939,599 TLLP common units and 26,753,205 QEPM common units outstanding. Based on the 23,051,455 QEPM common units outstanding at such date that are owned by QEPM unaffiliated unitholders and eligible for exchange into TLLP common units pursuant to the merger agreement, TLLP expects to issue approximately 7,118,289 TLLP common units in connection with the merger.

Support Agreement (see page 75)

In connection with the merger agreement, QEPM, QEP Field Services and TLLP entered into the support agreement dated April 6, 2015. Pursuant to the support agreement, TLLP and QEP Field Services have agreed to

vote any QEPM common units or QEPM subordinated units owned by them or their subsidiaries in favor of the adoption of the merger agreement and the merger at any meeting of QEPM’s unitholders. In addition, pursuant to the support agreement, QEP Field Services and TLLP granted an irrevocable proxy to a member of the QEPM Conflicts Committee to vote such units accordingly. QEP Field Services currently owns directly 26,705,000 QEPM subordinated units representing 100% of the outstanding QEPM subordinated units. The support agreement will terminate upon the completion of the merger, the termination of the merger agreement, the QEPM Conflicts Committee making a change in recommendation or the written agreement of TLLP, QEP Field Services and the QEPM Conflicts Committee on behalf of QEPM.

Directors and Officers of TLLP GP and QEPM GP (see page 108)

Tesoro, the sole member of TLLP GP, has the power to appoint and remove all of the directors of TLLP GP. TLLP has indirect power to cause the appointment or removal of the directors of QEPM GP, an indirect wholly owned subsidiary of TLLP. Each of the executive officers of TLLP GP is currently expected to remain an executive officer of TLLP GP following the merger. TLLP has not yet determined whether any directors or executive officers of QEPM GP will serve as directors or executive officers of TLLP GP following the merger. In the absence of any changes, the current directors of TLLP GP will continue as directors following the merger.

The following persons currently serve as directors and executive officers of TLLP GP and QEPM GP:

Market Prices of TLLP Common Units and QEPM Common Units Prior to Announcing the Proposed Merger (see page 33)

TLLP’s common units are traded on the NYSE under the ticker symbol “TLLP.” QEPM’s common units are traded on the NYSE under the ticker symbol “QEPM.” The following table shows the closing prices of TLLP common units and QEPM common units on December 1, 2014 (the last full trading day before TLLP’s initial proposal to acquire all of the QEPM common units owned by the public) and on April 6, 2015 (the day TLLP and QEPM entered into and announced the merger agreement).

The Special Unitholder Meeting (see page 45)

Time, Place and Date. The special meeting will take place at 19100 Ridgewood Parkway, San Antonio, Texas 78259, on July 21, 2015 at 8:00 a.m., local time. The special meeting may be adjourned or postponed to another date or place for proper purposes, including for the purpose of soliciting additional proxies.

Purposes. The purposes of the special meeting are to consider and vote on the approval and adoption of the merger agreement and the merger and to transact other business as may be properly presented at the special meeting or any adjournments of the special meeting. At the present time, QEPM knows of no other matters that will be presented for consideration at the special meeting.

Quorum. The holders of a majority of each class of units voting at the special meeting outstanding on the record date present in person or by proxy at the special meeting will constitute a quorum and will permit QEPM to conduct the proposed business at the special meeting. Representatives of QEPM GP will be present in person on behalf of QEPM GP at the special meeting.

Record Date. The close of business on June 8, 2015 is the record date.

Units Entitled to Vote. Holders of QEPM common units or QEPM subordinated units as of the close of business on the record date may vote at the special meeting. On that date, there were 26,753,205 QEPM common units outstanding and 26,705,000 QEPM subordinated units outstanding. Each holder of QEPM common units or QEPM subordinated units entitled to vote at the special meeting may cast one vote for each QEPM common unit or each QEPM subordinated unit that such holder owned on the close of business on the record date.

Votes Required. The affirmative vote of holders of at least a majority of the outstanding QEPM unaffiliated units is required to approve and adopt the merger agreement and merger. As of the record date, there were                  QEPM unaffiliated units outstanding. For purposes of determining whether the merger agreement and the merger have been approved and adopted by the QEPM unaffiliated units, QEPM common units held by QEP Field Services, a wholly owned subsidiary of TLLP, and by directors and officers of QEPM GP will not be counted toward the required majority vote of outstanding QEPM unaffiliated units.

The affirmative vote of holders of at least a majority of the outstanding QEPM subordinated units is also required to approve and adopt the merger Agreement and the merger. QEP Field Services owns all of the outstanding QEPM subordinated units and has agreed in the support agreement to vote these units at the special meeting in favor of the merger agreement and the merger.

The failure of a holder of QEPM unaffiliated units to vote in person or by proxy will have the effect of a vote against approval and adoption of the merger agreement and the merger. If you sign and return your proxy card but do not indicate how you want to vote, your proxy will be counted as a vote in favor of the approval and adoption of the merger agreement and the merger.

Recommendation to QEPM Unitholders (see page 59)

The members of QEPM Conflicts Committee considered the benefits of the merger and the related transactions as well as the associated risks and determined in good faith that it is in the best interests of QEPM and the QEPM unaffiliated unitholders and not adverse to the best interests of the Partnership Group (as defined in QEPM’s partnership agreement) for QEPM to enter into the merger agreement and to consummate the transactions contemplated thereby, including the merger. The QEPM Conflicts Committee also recommended that the QEPM Board and QEPM unaffiliated unitholders approve the merger agreement and the merger. The QEPM Board also approved the merger agreement and the merger and recommends that the QEPM unitholders, including the QEPM unaffiliated unitholders, vote to approve the merger agreement and the merger.

QEPM’s Reasons for the Merger (see page 59)

The QEPM Conflicts Committee considered many factors in making its determination and recommendation that the merger agreement and the merger are in the best interests of QEPM and QEPM’s unaffiliated unitholders and not adverse to the best interests of QEPM and its subsidiaries. The committee consulted with its financial and legal advisors and viewed the following factors, among others described in greater detail under “The Merger — Recommendation of the QEPM Conflicts Committee and the QEPM Board and Reasons for the Merger,” as being generally positive or favorable in coming to its determination and related recommendations:

The QEPM Conflicts Committee considered the following factors to be generally negative or unfavorable in making its determination and recommendations:

Opinion of the QEPM Conflicts Committee’s Financial Advisor (see page 65)

In connection with the merger, TPH delivered an opinion to the QEPM Conflicts Committee as to the fairness, from a financial point of view, to the QEPM unaffiliated unitholders of the exchange ratio provided in the merger pursuant to the merger agreement. The QEPM Conflicts Committee retained TPH to act as its financial advisor and to provide its opinion.

The full text of TPH’s written opinion, dated April 6, 2015, is attached to this proxy statement/prospectus as Annex B and is incorporated by reference into this document. We encourage you to read this opinion carefully in its entirety for a description of the procedures followed, assumptions made, matters considered and qualifications

and limitations of the review undertaken. TPH’s opinion was provided to the QEPM Conflicts Committee in connection with the QEPM Conflicts Committee’s consideration of the merger, does not address any other aspect of the proposed merger and does not constitute a recommendation as to how any holder of interests in QEPM or any other party to the merger should vote or act with respect to the merger, or any other matter. See “The Merger — Opinion of the QEPM Conflicts Committee’s Financial Advisor” beginning on page 64.

The Merger Agreement (see page 76)

The merger agreement is attached to this proxy statement/prospectus as Annex A and is incorporated by reference into this document. You are encouraged to read the merger agreement because it is the legal document that governs the merger.

What Needs to Be Done to Complete the Merger

TLLP and QEPM will complete the merger only if the conditions set forth in the merger agreement are satisfied or, in some cases, waived. The obligations of TLLP and QEPM to complete the merger are subject to, among other things, the following conditions:

The obligation of TLLP, TLLP GP and MergerCo to complete the merger is further subject to the following conditions:

The obligation of QEPM and QEPM GP to complete the merger is further subject to the following conditions:

Each of TLLP, TLLP GP, MergerCo the TLLP Board, QEPM, QEPM GP and the QEPM Board (with the approval of the TLLP Board or the QEPM Conflicts Committee, as applicable) may waive any of the conditions to its obligation to complete the merger (other than receipt of QEPM unitholder approval) subject to compliance with applicable law.

No Solicitation

QEPM and QEPM GP have agreed that they shall not, and they shall cause their subsidiaries not to and direct and use commercially reasonable best efforts to cause their respective representatives not to, directly or indirectly, take any action to solicit, initiate, or knowingly encourage or knowingly facilitate the making of any QEPM takeover proposal (as defined in the merger agreement) or any inquiry with respect thereto or engage in discussions or negotiations with any person or entity with respect thereto (except to notify such person or entity of the existence of these provisions), or disclose any non-public information or afford access to properties, books or records to, any person or entity that has made, or to the knowledge of QEPM or QEPM GP is considering making, any QEPM takeover proposal or any inquiry with respect thereto, or approve or recommend, or propose to approve or recommend, or execute or enter into any letter of intent, agreement in principle, merger agreement, option agreement, acquisition agreement or other similar agreement relating to a QEPM takeover proposal, or propose publicly or agree to do any of the foregoing relating to a QEPM takeover proposal or any inquiry with respect thereto.

Notwithstanding the foregoing, subject to certain limitations, at any time prior to receipt of QEPM unitholder approval, QEPM and QEPM GP may furnish information to the person or entity making a QEPM takeover proposal and participate in discussions with such person or entity if and only if the QEPM Conflicts Committee determines, after consultation with its financial advisor and legal counsel, that the QEPM takeover proposal constitutes or is likely to result in a superior proposal and that the failure to do so would not be in the best interests of the QEPM unaffiliated unitholders.

Please read “The Merger Agreement — Additional Agreements, Covenants, Rights and Obligations — No Solicitation” for more information.

Change in Recommendation

The QEPM Conflicts Committee is permitted to withdraw, modify or qualify in any manner adverse to TLLP its recommendation of the merger agreement and the merger, if, prior to receipt of QEPM unitholder approval, the QEPM Conflicts Committee determines, after consultation with its outside legal counsel, that a failure to change its recommendation would not be in the best interests of the QEPM unaffiliated unitholders, the QEPM Conflicts Committee may change its recommendation.

Please read “The Merger Agreement — Additional Agreements, Covenants, Rights and Obligations — No Solicitation” for more information.

Termination of the Merger Agreement

The parties to the merger agreement may terminate the merger agreement by mutual written agreement at any time without completing the merger, even after the QEPM unitholders have approved the merger agreement and the merger.

In addition, TLLP or QEPM may terminate the merger agreement on its own upon written notice to the other without completing the merger if:

The QEPM Conflicts Committee, on behalf of QEPM, may terminate the merger agreement:

TLLP may terminate the merger agreement:

Material U.S. Federal Income Tax Consequences of the Merger (see page 139)

Tax matters associated with the merger are complicated. The U.S. federal income tax consequences of the merger to a QEPM unaffiliated unitholder will depend on such unitholder’s own situation. The tax discussions in this proxy statement/prospectus focus on the U.S. federal income tax consequences generally applicable to individuals who are residents or citizens of the United States that hold their QEPM common units as capital assets, and these discussions have only limited application to other unitholders, including those subject to special tax treatment. QEPM unaffiliated unitholders are urged to consult their tax advisors for a full understanding of the U.S. federal, state, local and foreign tax consequences of the merger that will be applicable to them.

QEPM expects to receive an opinion from Andrews Kurth to the effect that no gain or loss should be recognized by the QEPM unaffiliated unitholders as a result of the receipt of TLLP common units in the merger, other than any income or gain resulting from either (i) any actual or constructive distribution of cash, including as a result of any decrease in partnership liabilities pursuant to Section 752 of the Internal Revenue Code , or (ii) any cash received in lieu of any fractional TLLP common units. TLLP expects to receive an opinion from Norton Rose Fulbright to the effect that no gain or loss should be recognized by TLLP unaffiliated unitholders as a result of the merger (other than gain resulting from any decrease in partnership liabilities pursuant to Section 752 of the Internal Revenue Code). Opinions of counsel, however, are subject to certain limitations and are not binding on the Internal Revenue Service, or “IRS,” and no assurance can be given that the IRS would not successfully assert a contrary position regarding the merger and the opinions of counsel.

The U.S. federal income tax consequences described above may not apply to all holders of TLLP common units and QEPM common units. Please read “Material U.S. Federal Income Tax Consequences of the Merger” beginning on page 138 for a more complete discussion of the U.S. federal income tax consequences of the merger.

Comparison of the Rights of TLLP and QEPM Unitholders (see page 113)

QEPM unitholders will own TLLP common units following the completion of the merger, and their rights associated with those TLLP common units will be governed by TLLP’s partnership agreement (which differs in a number of respects from QEPM’s partnership agreement) and the Delaware Act.

Other Information Related to the Merger (see page 74)

No Dissenters’ or Appraisal Rights

QEPM unitholders do not have dissenters’ or appraisal rights under QEPM’s partnership agreement, the merger agreement or the Delaware Act.

Antitrust and Regulatory Matters

Due to rules applicable to partnerships and the common control of QEPM and TLLP, no filing is required under the Hart-Scott-Rodino Act (the “HSR Act”) and the rules promulgated thereunder by the FTC. However, at any time before or after completion of the merger, the Department of Justice (the “DOJ”), the Federal Trade Commission (the “FTC”), or any state may request additional information or could take such action under the antitrust laws as it deems necessary or desirable in the public interest.

Listing of Common Units to be Issued in the Merger; Delisting and Deregistration of QEPM Common Units

TLLP expects to obtain approval to list on the NYSE the TLLP common units to be issued pursuant to the merger agreement, which approval is a condition to closing the merger. Upon completion of the merger, QEPM common units currently listed on the NYSE will cease to be listed on the NYSE and will be subsequently deregistered under the Exchange Act.

Accounting Treatment

The proposed merger will be accounted for in accordance with Accounting Standards Codification 810, Consolidations — Overall — Changes in Parent’s Ownership Interest in a Subsidiary, which is referred to as ASC 810. Changes in TLLP’s ownership interest in QEPM, while TLLP retains its controlling financial interest in QEPM, will be accounted for as an equity transaction and no gain or loss will be recognized as a result of the proposed merger. The proposed merger represents TLLP’s acquisition of the noncontrolling interests in QEPM.

Pending Litigation

On May 19, 2015, Randy Behner, a purported unitholder of QEPM, filed a putative class action lawsuit in the United States District Court for the Western District of Texas on behalf of the unitholders of QEPM, and the lawsuit is captioned Randy Behner v. QEP Midstream Partners, LP, Tesoro Logistics LP, Susan O. Rheney, Don A. Turkleson, and Gregory C. King, Civil Action No. 5:15-cv-415. On May 22, 2015, W. Joss Sanderson, a purported unitholder of QEPM, filed a substantially similar putative class action lawsuit in the United States District Court for the Western District of Texas on behalf of the unitholders of QEPM, and the lawsuit is captioned W. Joss Sanderson v. QEP Midstream Partners, LP, Tesoro Logistics LP, Susan O. Rheney, Don A. Turkleson, and Gregory C. King, Civil Action No. 5:15-cv-428. The complaints are similar and allege, among other things, that the registration statement on Form S-4 filed with the SEC is false and materially misleading and that the defendants have violated Sections 14(a) and 20(a) of the Securities Exchange Act of 1934 and Rule 14a-9 promulgated thereunder. The plaintiffs seek (i) to enjoin the defendants from finalizing and consummating the proposed merger between QEPM and TLLP unless and until the defendants provide additional disclosures and (ii) the implementation of a constructive trust, in favor of the plaintiffs, upon any benefits purportedly improperly received by defendants as a result of their conduct.

While TLLP and QEPM cannot predict the outcome of these lawsuits, nor can TLLP and QEPM predict the amount of time and expense that will be required to resolve these lawsuits, TLLP, QEPM and the individual defendants named in these lawsuits deny the allegations and intend to defend vigorously against them.

Summary of Risk Factors (see page 34)

You should consider carefully all of the risk factors together with all of the other information included in this proxy statement/prospectus before deciding how to vote. The risks related to the merger and the related transactions, TLLP’s business, TLLP common units and risks resulting from TLLP’s organizational structure are described under the caption “Risk Factors” beginning on page 33 of this proxy statement/prospectus. Some of these risks include, but are not limited to, those described below:

Organizational Chart

Before the Merger

The following simplified diagram depicts TLLP’s organizational structure prior to giving effect to the merger. This diagram is provided for illustrative purposes only and does not show all legal entities or obligations of such entities.

After the Merger

The following simplified diagram depicts TLLP’s organizational structure after giving effect to the merger. This diagram is provided for illustrative purposes only and does not show all legal entities or obligations of such entities.

SUMMARY HISTORICAL AND PRO FORMA FINANCIAL AND OPERATING INFORMATION OF

TLLP AND QEPM

The following tables set forth, for the periods and at the dates indicated, summary historical financial and operating information for TLLP, summary historical financial information for QEPM and summary unaudited pro forma financial information for TLLP after giving effect to the proposed merger with QEPM. The summary historical financial data as of and for each of the years ended December 31, 2012, 2013 and 2014 are derived from and should be read in conjunction with the audited financial statements and accompanying footnotes of TLLP and QEPM, respectively. The summary historical financial data as of and for the three months ended March 31, 2015 and 2014, respectively, are derived from and should be read in conjunction with the unaudited condensed combined consolidated financial statements and accompanying footnotes of TLLP and QEPM, respectively.

TLLP’s and QEPM’s consolidated balance sheets as of December 31, 2013 and 2014 and as of March 31, 2015, and the related statements of consolidated operations, comprehensive income, cash flows and equity for each of the three years in the period ended December 31, 2014 and the three months ended March 31, 2015 and 2014 are incorporated by reference into this proxy statement/prospectus from TLLP’s and QEPM’s respective Annual Reports on Form 10-K for the year ended December 31, 2014, and their Quarterly Reports on Form 10-Q for the three months ended March 31, 2015.

The summary unaudited pro forma condensed consolidated financial statements of TLLP show the pro forma effect of TLLP’s proposed merger with QEPM. For a complete discussion of the pro forma adjustments underlying the amounts in the table on the following page, please read “Unaudited Pro Forma Condensed Consolidated Financial Statements” beginning on page F-2 of this proxy statement/prospectus.

On December 2, 2014, pursuant to a definitive membership interest purchase agreement (“the MIPA”), TLLP completed the purchase from QEP Field Services Company (“QEPFSC”) of all the issued and outstanding membership interests of QEP Field Services, which assets are referred to as the “Rockies Natural Gas Business,” for approximately $2.5 billion in cash, subject to customary post closing adjustments (the “Rockies Natural Gas Business Acquisition”). Pursuant to the MIPA, TLLP acquired all of the assets and certain liabilities of QEPFS, excluding the Haynesville gathering system, which was retained by QEPFSC (the “QEP Retained Assets”).

As part of the Rockies Natural Gas Business Acquisition, TLLP acquired QEPM GP and related incentive distribution rights, 3,701,750 QEPM common units and 26,705,000 QEPM subordinated units on December 2, 2014, and QEPM became a consolidated subsidiary of TLLP for financial accounting and reporting purposes. The proposed merger will be accounted for in accordance with Accounting Standards Codification 810, Consolidations — Overall — Changes in Parent’s Ownership Interest in a Subsidiary, which is referred to as ASC 810. Changes in TLLP’s ownership interest in QEPM, while TLLP retains its controlling financial interest in QEPM, will be accounted for as an equity transaction and no gain or loss will be recognized as a result of the proposed merger. The proposed merger represents TLLP’s acquisition of the noncontrolling interests in QEPM.

During the third quarter of 2014, pursuant to a Contribution, Conveyance and Assumption Agreement, TLLP acquired from Tesoro three truck terminals, ten storage tanks, two rail loading and unloading facilities and a refined products pipeline (the “West Coast Logistics Assets”) for approximately $270 million, comprised of $243 million in cash and the remaining $27 million from the issuance of equity to TLLP GP (which partnership units consisted of the number of general partner units necessary to increase its ownership to 2% and the remainder of which were common units). The acquisition was completed in two phases, which occurred on July 1, 2014 and on September 30, 2014 (“West Coast Logistics Assets Acquisition”).

The unaudited pro forma condensed combined consolidated financial information of TLLP reflects adjustments to the historical statement of combined consolidated operations (the “Statement of Operations”) of TLLP to give effect to (i) the Rockies Natural Gas Business Acquisition, (ii) the offering of $1.3 billion aggregate principal amount of new Senior Notes due 2019 and 2022 on October 29, 2014 (“October Debt Offering”) and use of the proceeds from the October Debt Offering to fund a portion of the purchase price of the Rockies Natural Gas Business and repay $243 million outstanding under TLLP’s revolving credit agreement which was used to fund the West Coast Logistics Assets Acquisition, (iii) the entering into and borrowings under TLLP’s amended and restated credit agreement on December 2, 2014 (“New Credit Agreement”) to fund a portion of the purchase price of the Rockies Natural Gas Business, (iv) the offering of common units on October 24, 2014, with an aggregate value of $1.3 billion, which included the purchase of common units equal to $500 million by Tesoro and TLLP GP making a capital contribution to acquire general partner units to maintain its current 2% general partner interest in TLLP (“October Equity Offering”), and the use of the net proceeds from the October Equity Offering to fund a portion of the purchase price of the Rockies Natural Gas Business Acquisition, (v) the West Coast Logistics Assets Acquisition, (vi) the proposed merger between TLLP and QEPM and (vii) the payment of fees and expenses in connection with each of the foregoing. These items are collectively referred to as the “Pro Forma Statement of Operations Transactions.” The unaudited pro forma condensed combined consolidated financial information of TLLP reflects adjustments to the historical balance sheet (the “Balance Sheet”) of TLLP to give effect to (i) the proposed merger between TLLP and QEPM and (ii) the payment of fees and expenses in connection with the Merger. These items are collectively referred to as the “Pro Forma Balance Sheet Transactions.”

The unaudited pro forma condensed consolidated financial statements have been prepared to assist in the analysis of financial effects of the proposed merger between TLLP and QEPM. The unaudited pro forma condensed statements of consolidated operations for the year ended December 31, 2014 and the three months ended March 31, 2015 assume the Pro Forma Statement of Operations Transactions had taken place as of January 1, 2014. The unaudited pro forma condensed consolidated balance sheet as of March 31, 2015 assumes the Pro Forma Balance Sheet Transactions had taken place as of March 31, 2015. The unaudited pro forma condensed consolidated financial statements are based upon assumptions that TLLP and QEPM believe are reasonable under the circumstances, and are intended for informational purposes only. They are not necessarily indicative of the financial results that would have occurred if the transactions described herein had taken place on the dates indicated, nor are they indicative of the future consolidated results of the combined entity.

TLLP’s non-generally accepted accounting principles, or non-GAAP, financial measures of EBITDA, Adjusted EBITDA and Distributable Cash Flow are presented in the summary historical and pro forma financial information. Please read “— Non-GAAP Financial Measures,” which provides the necessary explanations for these non-GAAP financial measures and reconciliations to their most closely related GAAP financial measures.

For information regarding the effect of the proposed merger on pro forma distributions to QEPM unitholders, please read “Comparative Per Unit Information.” For additional financial information, please read “Selected Financial Data and Pro Forma Information of TLLP and QEPM” on page 96.

Summary Historical and Pro Forma Financial Information of TLLP

The following table should be read together with, and is qualified in its entirety by reference to, the historical combined consolidated financial statements and the accompanying notes incorporated by reference from TLLP’s Annual Report on Form 10-K for the year ended December 31, 2014 and TLLP’s Quarterly Report on Form 10-Q for the three months ended March 31, 2015, each incorporated herein by reference. The table should also be read together with “Unaudited Pro Forma Condensed Combined Consolidated Financial Information” included elsewhere in this document, “Item 7. Management’s Discussion and Analysis of Financial Condition and Results of Operations” incorporated by reference from TLLP’s Annual Reports on Form 10-K for the year ended December 31, 2014.

Summary Historical Financial Information of QEPM

The following table should be read together with, and is qualified in its entirety by reference to, the historical combined consolidated financial statements and the accompanying notes incorporated by reference from QEPM’s Annual Report on Form 10-K for the year ended December 31, 2014 and QEPM’s Quarterly Report on Form 10-Q for the three months ended March 31, 2015, each incorporated herein by reference. The table should also be read together with “Unaudited Pro Forma Condensed Combined Consolidated Financial Information” included elsewhere in this document, “Item 7. Management’s Discussion and Analysis of Financial Condition and Results of Operations” incorporated by reference from QEPM’s Annual Reports on Form 10-K for the year ended December 31, 2014.

Non-GAAP Financial Measures

This section provides reconciliations of TLLP’s and QEPM’s non-GAAP financial measures included in this proxy statement/prospectus to their most directly comparable financial measures calculated and presented in accordance with accounting principles generally accepted in the U.S., or “GAAP.”

Our management uses a variety of financial and operating measures to analyze operating segment performance. To supplement our financial information presented in accordance with U.S. GAAP, our management uses additional measures that are known as “non-GAAP” financial measures in its evaluation of past performance and prospects for the future. These measures are significant factors in assessing our operating results and profitability and include EBITDA, adjusted EBITDA and distributable cash flow.

EBITDA, adjusted EBITDA and distributable cash flow are not measures prescribed by U.S. GAAP but are supplemental financial measures that are used by management and may be used by external users of our financial statements, such as industry analysts, investors, lenders and rating agencies, to assess:

We believe that the presentation of EBITDA and adjusted EBITDA will provide useful information to investors in assessing our financial condition and results of operations. The U.S. GAAP measures most directly comparable to EBITDA and adjusted EBITDA are net income and net cash from operating activities. EBITDA and adjusted EBITDA should not be considered as an alternative to U.S. GAAP net income or net cash from operating activities. EBITDA and adjusted EBITDA have important limitations as an analytical tool, because they exclude some, but not all, of the items that affect net income and net cash from operating activities.

We believe that the presentation of distributable cash flow will provide useful information to investors as it is a widely accepted financial indicator used by investors to compare partnership performance and it provides investors an enhanced perspective of the operating performance of our assets and the cash our business is generating. The U.S. GAAP measure most directly comparable to distributable cash flow is net income.

These non-GAAP financial measures should not be considered in isolation or as a substitute for analysis of our results as reported under U.S. GAAP. Our definitions of these non-GAAP financial measures may not be comparable to similarly titled measures of other companies, because they may be defined differently by other companies in our industry, thereby diminishing their utility.

TLLP Non-GAAP Financial Measures

TLLP defines EBITDA as net income before depreciation and amortization expenses, net interest and financing costs and interest income. We define adjusted EBITDA as EBITDA plus or minus amounts determined to be “special items” by our management based on their unusual nature and relative significance to cash flow in a certain period. TLLP defines distributable cash flow as adjusted EBITDA plus or minus amounts determined to be “special items” by our management based on their relative significance to cash flow in a certain period. TLLP provides complete reconciliation and discussion of items identified as special items with our presentation of adjusted EBITDA and Distributable Cash Flow.

QEPM Non-GAAP Financial Measures

QEPM defines adjusted EBITDA as net income attributable to QEPM or predecessor plus any interest expense, net of other income, depreciation and amortization expense, QEPM’s share of unconsolidated affiliate’s depreciate and amortization expense, loss from early extinguishment of debt, net loss from asset sales and less any noncontrolling interest share of depreciation and amortization expense. QEPM defines distributable cash flow as adjusted EBITDA less cash interest paid, maintenance capital expenditures and cash adjustments for non-controlling interest and equity method investments, plus reimbursement by our customers for certain maintenance capital expenditures and non-cash long-term compensation expense.

TLLP

The following table presents a reconciliation of TLLP’s GAAP financial measure of net income to TLLP’s non-GAAP financial measures of EBITDA, adjusted EBITDA and distributable cash flow and a reconciliation of net cash from operating activities to EBITDA, on a historical and pro forma basis, as applicable for each of the periods indicated: