diff --git a/autoroll/go/autoroll-google3/google3_test.go b/autoroll/go/autoroll-google3/google3_test.go
index f50d12a..7b1c2c7 100644
--- a/autoroll/go/autoroll-google3/google3_test.go
+++ b/autoroll/go/autoroll-google3/google3_test.go
@@ -100,7 +100,7 @@
 	commits = append(commits, gb.CommitGen(ctx, "a.txt"))
 
 	mockChild.MockGetCommit(ctx, "master")
-	mockChild.MockLog(ctx, commits[0], commits[1])
+	mockChild.MockLog(ctx, git.LogFromTo(commits[0], commits[1]))
 	assert.NoError(t, a.UpdateStatus(ctx, "", true))
 	status := a.status.Get()
 	assert.Equal(t, 0, status.NumFailedRolls)
@@ -128,7 +128,7 @@
 
 	recent := []*autoroll.AutoRollIssue{issue4, issue3, issue2, issue1}
 	mockChild.MockGetCommit(ctx, "master")
-	mockChild.MockLog(ctx, commits[0], commits[2])
+	mockChild.MockLog(ctx, git.LogFromTo(commits[0], commits[2]))
 	assert.NoError(t, a.UpdateStatus(ctx, "error message", false))
 	status = a.status.Get()
 	assert.Equal(t, 2, status.NumFailedRolls)
@@ -141,7 +141,7 @@
 
 	// Test preserving error.
 	mockChild.MockGetCommit(ctx, "master")
-	mockChild.MockLog(ctx, commits[0], commits[2])
+	mockChild.MockLog(ctx, git.LogFromTo(commits[0], commits[2]))
 	assert.NoError(t, a.UpdateStatus(ctx, "", true))
 	status = a.status.Get()
 	assert.Equal(t, "error message", status.Error)
@@ -160,7 +160,7 @@
 		recent = append([]*autoroll.AutoRollIssue{issueI}, recent...)
 	}
 	mockChild.MockGetCommit(ctx, "master")
-	mockChild.MockLog(ctx, commits[0], commits[2])
+	mockChild.MockLog(ctx, git.LogFromTo(commits[0], commits[2]))
 	assert.NoError(t, a.UpdateStatus(ctx, "error message", false))
 	status = a.status.Get()
 	assert.Equal(t, recent_rolls.RECENT_ROLLS_LENGTH+1, status.NumFailedRolls)
@@ -188,7 +188,7 @@
 	closeIssue(issue2, autoroll.ROLL_RESULT_SUCCESS)
 	assert.NoError(t, a.AddOrUpdateIssue(ctx, issue2, http.MethodPut))
 	mockChild.MockGetCommit(ctx, "master")
-	mockChild.MockLog(ctx, commits[1], commits[2])
+	mockChild.MockLog(ctx, git.LogFromTo(commits[1], commits[2]))
 	assert.NoError(t, a.UpdateStatus(ctx, "", true))
 	deepequal.AssertDeepEqual(t, []*autoroll.AutoRollIssue{issue2, issue1}, a.status.Get().Recent)
 
@@ -198,7 +198,7 @@
 	issue4 := makeIssue(4, commits[2])
 	assert.NoError(t, a.AddOrUpdateIssue(ctx, issue4, http.MethodPost))
 	mockChild.MockGetCommit(ctx, "master")
-	mockChild.MockLog(ctx, commits[1], commits[2])
+	mockChild.MockLog(ctx, git.LogFromTo(commits[1], commits[2]))
 	assert.NoError(t, a.UpdateStatus(ctx, "", true))
 	issue3.Closed = true
 	issue3.Result = autoroll.ROLL_RESULT_FAILURE
@@ -209,7 +209,7 @@
 	closeIssue(issue5, autoroll.ROLL_RESULT_SUCCESS)
 	assert.NoError(t, a.AddOrUpdateIssue(ctx, issue5, http.MethodPut))
 	mockChild.MockGetCommit(ctx, "master")
-	mockChild.MockLog(ctx, commits[2], commits[2])
+	mockChild.MockLog(ctx, git.LogFromTo(commits[2], commits[2]))
 	assert.NoError(t, a.UpdateStatus(ctx, "", true))
 	issue4.Closed = true
 	issue4.Result = autoroll.ROLL_RESULT_FAILURE
diff --git a/autoroll/go/repo_manager/android_repo_manager.go b/autoroll/go/repo_manager/android_repo_manager.go
index 1937f49..28fc1d2 100644
--- a/autoroll/go/repo_manager/android_repo_manager.go
+++ b/autoroll/go/repo_manager/android_repo_manager.go
@@ -18,6 +18,7 @@
 	"go.skia.org/infra/go/common"
 	"go.skia.org/infra/go/exec"
 	"go.skia.org/infra/go/gerrit"
+	"go.skia.org/infra/go/git"
 	"go.skia.org/infra/go/sklog"
 	"go.skia.org/infra/go/util"
 	"go.skia.org/infra/go/vcsinfo"
@@ -281,7 +282,7 @@
 	// Create the roll CL.
 
 	cr := r.childRepo
-	commits, err := cr.RevList(ctx, fmt.Sprintf("%s..%s", from.Id, to.Id))
+	commits, err := cr.RevList(ctx, git.LogFromTo(from.Id, to.Id))
 	if err != nil {
 		return 0, fmt.Errorf("Failed to list revisions: %s", err)
 	}
@@ -508,7 +509,7 @@
 		return []*revision.Revision{}, nil
 	}
 	// Only consider commits on the "main" branch as roll candidates.
-	commits, err := r.childRepo.RevList(ctx, "--ancestry-path", "--first-parent", fmt.Sprintf("%s..%s", lastRollRev.Id, head))
+	commits, err := r.childRepo.RevList(ctx, "--ancestry-path", "--first-parent", git.LogFromTo(lastRollRev.Id, head))
 	if err != nil {
 		return nil, err
 	}
diff --git a/autoroll/go/repo_manager/copy_repo_manager.go b/autoroll/go/repo_manager/copy_repo_manager.go
index 174daf2..2cfcf7f 100644
--- a/autoroll/go/repo_manager/copy_repo_manager.go
+++ b/autoroll/go/repo_manager/copy_repo_manager.go
@@ -163,7 +163,7 @@
 	}()
 
 	// List the revisions in the roll.
-	commits, err := rm.childRepo.RevList(ctx, fmt.Sprintf("%s..%s", from.Id, to.Id))
+	commits, err := rm.childRepo.RevList(ctx, git.LogFromTo(from.Id, to.Id))
 	if err != nil {
 		return 0, fmt.Errorf("Failed to list revisions: %s", err)
 	}
diff --git a/autoroll/go/repo_manager/deps_repo_manager.go b/autoroll/go/repo_manager/deps_repo_manager.go
index 9fd8a04..9f8d22f 100644
--- a/autoroll/go/repo_manager/deps_repo_manager.go
+++ b/autoroll/go/repo_manager/deps_repo_manager.go
@@ -15,6 +15,7 @@
 	"go.skia.org/infra/autoroll/go/revision"
 	"go.skia.org/infra/go/exec"
 	"go.skia.org/infra/go/gerrit"
+	"go.skia.org/infra/go/git"
 	"go.skia.org/infra/go/issues"
 	"go.skia.org/infra/go/sklog"
 	"go.skia.org/infra/go/util"
@@ -162,7 +163,7 @@
 
 	// Create the roll CL.
 	cr := dr.childRepo
-	commits, err := cr.RevList(ctx, fmt.Sprintf("%s..%s", from.Id, to.Id))
+	commits, err := cr.RevList(ctx, git.LogFromTo(from.Id, to.Id))
 	if err != nil {
 		return 0, fmt.Errorf("Failed to list revisions: %s", err)
 	}
diff --git a/autoroll/go/repo_manager/freetype_repo_manager.go b/autoroll/go/repo_manager/freetype_repo_manager.go
index 038f4b5..eb038b1 100644
--- a/autoroll/go/repo_manager/freetype_repo_manager.go
+++ b/autoroll/go/repo_manager/freetype_repo_manager.go
@@ -182,7 +182,7 @@
 	}
 
 	// Check modules.cfg. Give up if it has changed.
-	diff, err := rm.localChildRepo.Git(ctx, "diff", "--name-only", fmt.Sprintf("%s..%s", from.Id, to.Id))
+	diff, err := rm.localChildRepo.Git(ctx, "diff", "--name-only", git.LogFromTo(from.Id, to.Id))
 	if err != nil {
 		return "", nil, err
 	}
diff --git a/autoroll/go/repo_manager/freetype_repo_manager_test.go b/autoroll/go/repo_manager/freetype_repo_manager_test.go
index 4fbd3c5..5bb6e67 100644
--- a/autoroll/go/repo_manager/freetype_repo_manager_test.go
+++ b/autoroll/go/repo_manager/freetype_repo_manager_test.go
@@ -110,7 +110,7 @@
 	parentMaster, err := git.GitDir(parent.Dir()).RevParse(ctx, "HEAD")
 	assert.NoError(t, err)
 	mockParent.MockReadFile(ctx, "DEPS", parentMaster)
-	mockChild.MockLog(ctx, childCommits[0], "master")
+	mockChild.MockLog(ctx, git.LogFromTo(childCommits[0], "master"))
 	mockChild.MockGetCommit(ctx, childCommits[0])
 
 	rm, err := NewFreeTypeRepoManager(ctx, cfg, wd, g, recipesCfg, "fake.server.com", "", urlmock.Client(), gerritCR(t, g), false)
@@ -135,7 +135,7 @@
 	parentMaster, err := git.GitDir(parentRepo.Dir()).RevParse(ctx, "HEAD")
 	assert.NoError(t, err)
 	mockParent.MockReadFile(ctx, "DEPS", parentMaster)
-	mockChild.MockLog(ctx, childCommits[0], "master")
+	mockChild.MockLog(ctx, git.LogFromTo(childCommits[0], "master"))
 	mockChild.MockGetCommit(ctx, childCommits[0])
 	nextRollRev := childCommits[len(childCommits)-1]
 	assert.NoError(t, rm.Update(ctx))
@@ -154,7 +154,7 @@
 		rev, err := rm.GetRevision(ctx, c)
 		assert.NoError(t, err)
 		assert.Equal(t, c, rev.Id)
-		mockChild.MockLog(ctx, c, childCommits[0])
+		mockChild.MockLog(ctx, git.LogFromTo(c, childCommits[0]))
 		rp, err := rm.RolledPast(ctx, rev)
 		assert.NoError(t, err)
 		assert.False(t, rp)
@@ -169,7 +169,7 @@
 	parentMaster, err := git.GitDir(parentRepo.Dir()).RevParse(ctx, "HEAD")
 	assert.NoError(t, err)
 	mockParent.MockReadFile(ctx, "DEPS", parentMaster)
-	mockChild.MockLog(ctx, childCommits[0], "master")
+	mockChild.MockLog(ctx, git.LogFromTo(childCommits[0], "master"))
 	mockChild.MockGetCommit(ctx, childCommits[0])
 	nextRollRev := childCommits[1]
 	assert.NoError(t, rm.Update(ctx))
@@ -179,7 +179,7 @@
 	assert.NoError(t, SetStrategy(ctx, rm, strategy.ROLL_STRATEGY_BATCH))
 	mockParent.MockGetCommit(ctx, "master")
 	mockParent.MockReadFile(ctx, "DEPS", parentMaster)
-	mockChild.MockLog(ctx, childCommits[0], "master")
+	mockChild.MockLog(ctx, git.LogFromTo(childCommits[0], "master"))
 	mockChild.MockGetCommit(ctx, childCommits[0])
 	assert.NoError(t, rm.Update(ctx))
 	assert.Equal(t, childCommits[len(childCommits)-1], rm.NextRollRev().Id)
@@ -187,7 +187,7 @@
 	assert.NoError(t, SetStrategy(ctx, rm, strategy.ROLL_STRATEGY_SINGLE))
 	mockParent.MockGetCommit(ctx, "master")
 	mockParent.MockReadFile(ctx, "DEPS", parentMaster)
-	mockChild.MockLog(ctx, childCommits[0], "master")
+	mockChild.MockLog(ctx, git.LogFromTo(childCommits[0], "master"))
 	mockChild.MockGetCommit(ctx, childCommits[0])
 	assert.NoError(t, rm.Update(ctx))
 	assert.Equal(t, childCommits[1], rm.NextRollRev().Id)
@@ -201,7 +201,7 @@
 	parentMaster, err := git.GitDir(parentRepo.Dir()).RevParse(ctx, "HEAD")
 	assert.NoError(t, err)
 	mockParent.MockReadFile(ctx, "DEPS", parentMaster)
-	mockChild.MockLog(ctx, childCommits[0], "master")
+	mockChild.MockLog(ctx, git.LogFromTo(childCommits[0], "master"))
 	mockChild.MockGetCommit(ctx, childCommits[0])
 	nextRollRev := childCommits[len(childCommits)-1]
 	assert.NoError(t, rm.Update(ctx))
@@ -224,7 +224,7 @@
 	// Mock the initial change creation.
 	logStr := ""
 	childGitRepo := git.GitDir(childRepo.Dir())
-	commitsToRoll, err := childGitRepo.RevList(ctx, fmt.Sprintf("%s..%s", lastRollRev, nextRollRev))
+	commitsToRoll, err := childGitRepo.RevList(ctx, git.LogFromTo(lastRollRev, nextRollRev))
 	assert.NoError(t, err)
 	for _, c := range commitsToRoll {
 		mockChild.MockGetCommit(ctx, c)
diff --git a/autoroll/go/repo_manager/github_deps_repo_manager.go b/autoroll/go/repo_manager/github_deps_repo_manager.go
index 6ada471..ee6c244 100644
--- a/autoroll/go/repo_manager/github_deps_repo_manager.go
+++ b/autoroll/go/repo_manager/github_deps_repo_manager.go
@@ -304,7 +304,7 @@
 
 	// Build the commit message.
 	user, repo := GetUserAndRepo(rm.childRepoUrl)
-	commits, err := rm.childRepo.RevList(ctx, "--no-merges", fmt.Sprintf("%s..%s", from.Id, to.Id))
+	commits, err := rm.childRepo.RevList(ctx, "--no-merges", git.LogFromTo(from.Id, to.Id))
 	if err != nil {
 		return 0, fmt.Errorf("Failed to list revisions: %s", err)
 	}
diff --git a/autoroll/go/repo_manager/github_repo_manager.go b/autoroll/go/repo_manager/github_repo_manager.go
index 6db3d39..263b9bf 100644
--- a/autoroll/go/repo_manager/github_repo_manager.go
+++ b/autoroll/go/repo_manager/github_repo_manager.go
@@ -301,7 +301,7 @@
 
 	// Build the commit message.
 	user, repo := GetUserAndRepo(rm.childRepoURL)
-	commits, err := rm.childRepo.RevList(ctx, "--no-merges", fmt.Sprintf("%s..%s", from.Id, to.Id))
+	commits, err := rm.childRepo.RevList(ctx, "--no-merges", git.LogFromTo(from.Id, to.Id))
 	if err != nil {
 		return 0, fmt.Errorf("Failed to list revisions: %s", err)
 	}
diff --git a/autoroll/go/repo_manager/no_checkout_deps_repo_manager.go b/autoroll/go/repo_manager/no_checkout_deps_repo_manager.go
index 7b95630..14f4651 100644
--- a/autoroll/go/repo_manager/no_checkout_deps_repo_manager.go
+++ b/autoroll/go/repo_manager/no_checkout_deps_repo_manager.go
@@ -17,6 +17,7 @@
 	"go.skia.org/infra/go/depot_tools"
 	"go.skia.org/infra/go/exec"
 	"go.skia.org/infra/go/gerrit"
+	"go.skia.org/infra/go/git"
 	"go.skia.org/infra/go/gitiles"
 	"go.skia.org/infra/go/issues"
 	"go.skia.org/infra/go/sklog"
@@ -267,7 +268,7 @@
 	if rev.Id == rm.lastRollRev.Id {
 		return true, nil
 	}
-	commits, err := rm.childRepo.Log(ctx, rev.Id, rm.lastRollRev.Id)
+	commits, err := rm.childRepo.Log(ctx, git.LogFromTo(rev.Id, rm.lastRollRev.Id))
 	if err != nil {
 		return false, err
 	}
diff --git a/autoroll/go/repo_manager/no_checkout_deps_repo_manager_test.go b/autoroll/go/repo_manager/no_checkout_deps_repo_manager_test.go
index 48ece00..0a18186 100644
--- a/autoroll/go/repo_manager/no_checkout_deps_repo_manager_test.go
+++ b/autoroll/go/repo_manager/no_checkout_deps_repo_manager_test.go
@@ -79,7 +79,7 @@
 	parentMaster, err := git.GitDir(parent.Dir()).RevParse(ctx, "HEAD")
 	assert.NoError(t, err)
 	mockParent.MockReadFile(ctx, "DEPS", parentMaster)
-	mockChild.MockLog(ctx, childCommits[0], "master")
+	mockChild.MockLog(ctx, git.LogFromTo(childCommits[0], "master"))
 	mockChild.MockGetCommit(ctx, childCommits[0])
 
 	rm, err := NewNoCheckoutDEPSRepoManager(ctx, cfg, wd, g, recipesCfg, "fake.server.com", "", urlmock.Client(), gerritCR(t, g), false)
@@ -118,7 +118,7 @@
 	parentMaster, err := git.GitDir(parentRepo.Dir()).RevParse(ctx, "HEAD")
 	assert.NoError(t, err)
 	mockParent.MockReadFile(ctx, "DEPS", parentMaster)
-	mockChild.MockLog(ctx, childCommits[0], "master")
+	mockChild.MockLog(ctx, git.LogFromTo(childCommits[0], "master"))
 	mockChild.MockGetCommit(ctx, childCommits[0])
 	nextRollRev := childCommits[len(childCommits)-1]
 	assert.NoError(t, rm.Update(ctx))
@@ -139,7 +139,7 @@
 		rev, err := rm.GetRevision(ctx, c)
 		assert.NoError(t, err)
 		assert.Equal(t, c, rev.Id)
-		mockChild.MockLog(ctx, c, childCommits[0])
+		mockChild.MockLog(ctx, git.LogFromTo(c, childCommits[0]))
 		rp, err := rm.RolledPast(ctx, rev)
 		assert.NoError(t, err)
 		assert.False(t, rp)
@@ -155,7 +155,7 @@
 	parentMaster, err := git.GitDir(parentRepo.Dir()).RevParse(ctx, "HEAD")
 	assert.NoError(t, err)
 	mockParent.MockReadFile(ctx, "DEPS", parentMaster)
-	mockChild.MockLog(ctx, childCommits[0], "master")
+	mockChild.MockLog(ctx, git.LogFromTo(childCommits[0], "master"))
 	mockChild.MockGetCommit(ctx, childCommits[0])
 	nextRollRev := childCommits[1]
 	assert.NoError(t, rm.Update(ctx))
@@ -165,7 +165,7 @@
 	assert.NoError(t, SetStrategy(ctx, rm, strategy.ROLL_STRATEGY_BATCH))
 	mockParent.MockGetCommit(ctx, "master")
 	mockParent.MockReadFile(ctx, "DEPS", parentMaster)
-	mockChild.MockLog(ctx, childCommits[0], "master")
+	mockChild.MockLog(ctx, git.LogFromTo(childCommits[0], "master"))
 	mockChild.MockGetCommit(ctx, childCommits[0])
 	assert.NoError(t, rm.Update(ctx))
 	assert.Equal(t, childCommits[len(childCommits)-1], rm.NextRollRev().Id)
@@ -173,7 +173,7 @@
 	assert.NoError(t, SetStrategy(ctx, rm, strategy.ROLL_STRATEGY_SINGLE))
 	mockParent.MockGetCommit(ctx, "master")
 	mockParent.MockReadFile(ctx, "DEPS", parentMaster)
-	mockChild.MockLog(ctx, childCommits[0], "master")
+	mockChild.MockLog(ctx, git.LogFromTo(childCommits[0], "master"))
 	mockChild.MockGetCommit(ctx, childCommits[0])
 	assert.NoError(t, rm.Update(ctx))
 	assert.Equal(t, childCommits[1], rm.NextRollRev().Id)
@@ -188,7 +188,7 @@
 	parentMaster, err := git.GitDir(parentRepo.Dir()).RevParse(ctx, "HEAD")
 	assert.NoError(t, err)
 	mockParent.MockReadFile(ctx, "DEPS", parentMaster)
-	mockChild.MockLog(ctx, childCommits[0], "master")
+	mockChild.MockLog(ctx, git.LogFromTo(childCommits[0], "master"))
 	mockChild.MockGetCommit(ctx, childCommits[0])
 	nextRollRev := childCommits[len(childCommits)-1]
 	assert.NoError(t, rm.Update(ctx))
@@ -201,7 +201,7 @@
 	// Mock the initial change creation.
 	logStr := ""
 	childGitRepo := git.GitDir(childRepo.Dir())
-	commitsToRoll, err := childGitRepo.RevList(ctx, fmt.Sprintf("%s..%s", lastRollRev, nextRollRev))
+	commitsToRoll, err := childGitRepo.RevList(ctx, git.LogFromTo(lastRollRev, nextRollRev))
 	assert.NoError(t, err)
 	for _, c := range commitsToRoll {
 		mockChild.MockGetCommit(ctx, c)
@@ -301,7 +301,7 @@
 	parentMaster, err := git.GitDir(parentRepo.Dir()).RevParse(ctx, "HEAD")
 	assert.NoError(t, err)
 	mockParent.MockReadFile(ctx, "DEPS", parentMaster)
-	mockChild.MockLog(ctx, childCommits[0], "master")
+	mockChild.MockLog(ctx, git.LogFromTo(childCommits[0], "master"))
 	mockChild.MockGetCommit(ctx, childCommits[0])
 	nextRollRev := childCommits[len(childCommits)-1]
 	assert.NoError(t, rm.Update(ctx))
@@ -317,7 +317,7 @@
 	// Mock the initial change creation.
 	logStr := ""
 	childGitRepo := git.GitDir(childRepo.Dir())
-	commitsToRoll, err := childGitRepo.RevList(ctx, fmt.Sprintf("%s..%s", lastRollRev, nextRollRev))
+	commitsToRoll, err := childGitRepo.RevList(ctx, git.LogFromTo(lastRollRev, nextRollRev))
 	assert.NoError(t, err)
 	for _, c := range commitsToRoll {
 		mockChild.MockGetCommit(ctx, c)
diff --git a/autoroll/go/repo_manager/repo_manager.go b/autoroll/go/repo_manager/repo_manager.go
index 478da33..84b494ea0 100644
--- a/autoroll/go/repo_manager/repo_manager.go
+++ b/autoroll/go/repo_manager/repo_manager.go
@@ -311,7 +311,7 @@
 	if head == lastRollRev.Id {
 		return []*revision.Revision{}, nil
 	}
-	commits, err := r.childRepo.RevList(ctx, fmt.Sprintf("%s..%s", lastRollRev.Id, head))
+	commits, err := r.childRepo.RevList(ctx, git.LogFromTo(lastRollRev.Id, head))
 	if err != nil {
 		return nil, err
 	}
diff --git a/gitsync/go/gitsync/watcher.go b/gitsync/go/gitsync/watcher.go
index cb8b5ab..51691f5 100644
--- a/gitsync/go/gitsync/watcher.go
+++ b/gitsync/go/gitsync/watcher.go
@@ -126,7 +126,7 @@
 
 			if anc {
 				// Only get the commits between the old and new head.
-				revListStr = fmt.Sprintf("%s..%s", foundBranch.Head, newBranch.Head)
+				revListStr = git.LogFromTo(foundBranch.Head, newBranch.Head)
 			}
 		}
 
diff --git a/go/git/gitinfo/gitinfo.go b/go/git/gitinfo/gitinfo.go
index f1390b2..1b90967 100644
--- a/go/git/gitinfo/gitinfo.go
+++ b/go/git/gitinfo/gitinfo.go
@@ -15,6 +15,7 @@
 
 	"go.skia.org/infra/go/depot_tools"
 	"go.skia.org/infra/go/exec"
+	"go.skia.org/infra/go/git"
 	"go.skia.org/infra/go/sklog"
 	"go.skia.org/infra/go/tiling"
 	"go.skia.org/infra/go/util"
@@ -312,7 +313,7 @@
 func (g *GitInfo) IndexOf(ctx context.Context, hash string) (int, error) {
 	// Count the lines from running:
 	//   git rev-list --count <first-commit>..hash.
-	output, err := g.RevList(ctx, "--count", fmt.Sprintf("%s..%s", g.firstCommit, hash))
+	output, err := g.RevList(ctx, "--count", git.LogFromTo(g.firstCommit, hash))
 	if err != nil {
 		return 0, fmt.Errorf("git rev-list failed: %s", err)
 	}
diff --git a/go/git/repograph/shared_tests/shared_tests.go b/go/git/repograph/shared_tests/shared_tests.go
index 2ecc52c..dd150f0 100644
--- a/go/git/repograph/shared_tests/shared_tests.go
+++ b/go/git/repograph/shared_tests/shared_tests.go
@@ -385,7 +385,7 @@
 			if from == "" {
 				cmd = append(cmd, to)
 			} else {
-				cmd = append(cmd, "--ancestry-path", fmt.Sprintf("%s..%s", from, to))
+				cmd = append(cmd, "--ancestry-path", git.LogFromTo(from, to))
 			}
 			hashes, err := gitdir.RevList(ctx, cmd...)
 			assert.NoError(t, err)
@@ -702,7 +702,7 @@
 
 	check := func(from, to string, expectOrig []string) {
 		expect := util.CopyStringSlice(expectOrig)
-		revs, err := co.RevList(ctx, fmt.Sprintf("%s..%s", from, to))
+		revs, err := co.RevList(ctx, git.LogFromTo(from, to))
 		assert.NoError(t, err)
 		// Sanity check; assert that the commits returned from git are
 		// in reverse topological order.
diff --git a/go/git/util.go b/go/git/util.go
index aa1f3c1..c17178d 100644
--- a/go/git/util.go
+++ b/go/git/util.go
@@ -1,10 +1,24 @@
 package git
 
 import (
+	"fmt"
 	"net/url"
 	"strings"
 )
 
+// LogFromTo returns a string which is used to log from one commit to another.
+// It is important to note that:
+// - The results will include the second commit but not the first.
+// - The results include all commits reachable from the first commit which are
+//   not reachable from the second, ie. if there is a merge in the given
+//   range, the results will include that line of history and not just the
+//   commits which are descendants of the first commit. If you want only commits
+//   which are ancestors of the second commit AND descendants of the first, you
+//   should use LogLinear.
+func LogFromTo(from, to string) string {
+	return fmt.Sprintf("%s..%s", from, to)
+}
+
 // NormalizeURL strips everything from the URL except for the host and the path.
 // A trailing ".git" is also stripped. The purpose is to allow for small
 // variations in repo URL to be recognized as the same repo. The URL needs to
diff --git a/go/gitiles/gitiles.go b/go/gitiles/gitiles.go
index 7646a49..88fd638 100644
--- a/go/gitiles/gitiles.go
+++ b/go/gitiles/gitiles.go
@@ -206,14 +206,38 @@
 	return commitToLongCommit(&c)
 }
 
+// LogOption represents an optional parameter to a Log function.
+type LogOption string
+
+// LogReverse is a LogOption which indicates that the commits in the Log should
+// be returned in reverse order from the typical "git log" ordering, ie. each
+// commit's parents appear before the commit itself.
+func LogReverse() LogOption {
+	return LogOption("reverse=true")
+}
+
+// LogBatchSize is a LogOption which indicates the number of commits which
+// should be included in each batch of commits returned by Log.
+func LogBatchSize(n int) LogOption {
+	return LogOption(fmt.Sprintf("n=%d", n))
+}
+
 // logHelper is used to perform requests which are equivalent to "git log".
 // Loads commits in batches and calls the given function for each batch of
 // commits. If the function returns an error, iteration stops, and the error is
 // returned, unless it was ErrStopIteration.
-func (r *Repo) logHelper(ctx context.Context, urlTmpl, commit string, fn func(context.Context, []*vcsinfo.LongCommit) error) error {
+func (r *Repo) logHelper(ctx context.Context, url string, fn func(context.Context, []*vcsinfo.LongCommit) error, opts ...LogOption) error {
+	for _, opt := range opts {
+		url += "&" + string(opt)
+	}
+	start := ""
 	for {
 		var l Log
-		if err := r.getJson(ctx, fmt.Sprintf(urlTmpl, commit), &l); err != nil {
+		u := url
+		if start != "" {
+			u += "&s=" + start
+		}
+		if err := r.getJson(ctx, u, &l); err != nil {
 			return err
 		}
 		// Convert to vcsinfo.LongCommit.
@@ -233,20 +257,19 @@
 		if l.Next == "" {
 			return nil
 		} else {
-			commit = l.Next
+			start = l.Next
 		}
 	}
 }
 
-// Log returns Gitiles' equivalent to "git log" for the given start and end
-// commits.
-func (r *Repo) Log(ctx context.Context, from, to string) ([]*vcsinfo.LongCommit, error) {
+// Log returns Gitiles' equivalent to "git log" for the given expression.
+func (r *Repo) Log(ctx context.Context, logExpr string, opts ...LogOption) ([]*vcsinfo.LongCommit, error) {
 	rv := []*vcsinfo.LongCommit{}
-	tmpl := fmt.Sprintf(LOG_URL, r.URL, from+"..%s")
-	if err := r.logHelper(ctx, tmpl, to, func(ctx context.Context, commits []*vcsinfo.LongCommit) error {
+	url := fmt.Sprintf(LOG_URL, r.URL, logExpr)
+	if err := r.logHelper(ctx, url, func(ctx context.Context, commits []*vcsinfo.LongCommit) error {
 		rv = append(rv, commits...)
 		return nil
-	}); err != nil {
+	}, opts...); err != nil {
 		return nil, err
 	}
 	return rv, nil
@@ -256,9 +279,9 @@
 // ie. it only returns commits which are on the direct path from A to B, and
 // only on the "main" branch. This is as opposed to "git log from..to" which
 // returns all commits which are ancestors of 'to' but not 'from'.
-func (r *Repo) LogLinear(ctx context.Context, from, to string) ([]*vcsinfo.LongCommit, error) {
+func (r *Repo) LogLinear(ctx context.Context, from, to string, opts ...LogOption) ([]*vcsinfo.LongCommit, error) {
 	// Retrieve the normal "git log".
-	commits, err := r.Log(ctx, from, to)
+	commits, err := r.Log(ctx, git.LogFromTo(from, to), opts...)
 	if err != nil {
 		return nil, err
 	}
@@ -314,31 +337,37 @@
 	return rv, nil
 }
 
-// LogFn runs the given function for each commit in the log history reachable
-// from the given commit hash or ref name. It stops when ErrStopIteration is
-// returned.
-func (r *Repo) LogFn(ctx context.Context, to string, fn func(context.Context, *vcsinfo.LongCommit) error) error {
-	return r.LogFnBatch(ctx, to, func(ctx context.Context, commits []*vcsinfo.LongCommit) error {
+// LogFn runs the given function for each commit in the log for the given
+// expression. It stops when ErrStopIteration is returned.
+func (r *Repo) LogFn(ctx context.Context, logExpr string, fn func(context.Context, *vcsinfo.LongCommit) error, opts ...LogOption) error {
+	return r.LogFnBatch(ctx, logExpr, func(ctx context.Context, commits []*vcsinfo.LongCommit) error {
 		for _, c := range commits {
 			if err := fn(ctx, c); err != nil {
 				return err
 			}
 		}
 		return nil
-	})
+	}, opts...)
 }
 
 // LogFnBatch is the same as LogFn but it runs the given function over batches
 // of commits.
-func (r *Repo) LogFnBatch(ctx context.Context, to string, fn func(context.Context, []*vcsinfo.LongCommit) error) error {
-	return r.logHelper(ctx, fmt.Sprintf(LOG_URL, r.URL, "%s"), to, fn)
+func (r *Repo) LogFnBatch(ctx context.Context, logExpr string, fn func(context.Context, []*vcsinfo.LongCommit) error, opts ...LogOption) error {
+	url := fmt.Sprintf(LOG_URL, r.URL, logExpr)
+	return r.logHelper(ctx, url, fn, opts...)
 }
 
+// Ref represents a single ref, as returned by the API.
+type Ref struct {
+	Value string `json:"value"`
+}
+
+// RefsMap is the result of a request to REFS_URL.
+type RefsMap map[string]Ref
+
 // Branches returns the list of branches in the repo.
 func (r *Repo) Branches(ctx context.Context) ([]*git.Branch, error) {
-	branchMap := map[string]struct {
-		Value string `json:"value"`
-	}{}
+	branchMap := RefsMap{}
 	if err := r.getJson(ctx, fmt.Sprintf(REFS_URL, r.URL), &branchMap); err != nil {
 		return nil, err
 	}
diff --git a/go/gitiles/gitiles_test.go b/go/gitiles/gitiles_test.go
index 51a6b5d..bdce5ac 100644
--- a/go/gitiles/gitiles_test.go
+++ b/go/gitiles/gitiles_test.go
@@ -110,7 +110,7 @@
 		}
 		js := testutils.MarshalJSON(t, results)
 		js = ")]}'\n" + js
-		urlMock.MockOnce(fmt.Sprintf(LOG_URL, gb.RepoUrl(), fmt.Sprintf("%s..%s", from, to)), mockhttpclient.MockGetDialogue([]byte(js)))
+		urlMock.MockOnce(fmt.Sprintf(LOG_URL, gb.RepoUrl(), git.LogFromTo(from, to)), mockhttpclient.MockGetDialogue([]byte(js)))
 	}
 
 	// Return a slice of the hashes for the given commits.
@@ -123,9 +123,9 @@
 	}
 
 	// Verify that we got the correct list of commits from the call to Log.
-	checkGitiles := func(fn func(context.Context, string, string) ([]*vcsinfo.LongCommit, error), from, to string, expect []string) {
+	checkGitiles := func(fn func(context.Context, string, ...LogOption) ([]*vcsinfo.LongCommit, error), from, to string, expect []string) {
 		mockLog(from, to, expect)
-		log, err := fn(ctx, from, to)
+		log, err := fn(ctx, git.LogFromTo(from, to))
 		assert.NoError(t, err)
 		deepequal.AssertDeepEqual(t, hashes(log), expect)
 		assert.True(t, urlMock.Empty())
@@ -137,7 +137,7 @@
 	checkGit := func(from, to string, expect []string, args ...string) {
 		cmd := []string{"rev-list", "--date-order"}
 		cmd = append(cmd, args...)
-		cmd = append(cmd, fmt.Sprintf("%s..%s", from, to))
+		cmd = append(cmd, string(git.LogFromTo(from, to)))
 		output, err := repo.Git(ctx, cmd...)
 		assert.NoError(t, err)
 		log := strings.Split(strings.TrimSpace(output), "\n")
@@ -161,7 +161,11 @@
 	// ("git log --date-order --first-parent --ancestry-path).
 	checkLinear := func(from, to string, expect []string) {
 		checkGit(from, to, expect, "--first-parent", "--ancestry-path")
-		checkGitiles(r.LogLinear, from, to, expect)
+		mockLog(from, to, expect)
+		log, err := r.LogLinear(ctx, from, to)
+		assert.NoError(t, err)
+		deepequal.AssertDeepEqual(t, hashes(log), expect)
+		assert.True(t, urlMock.Empty())
 	}
 
 	// Test cases.
@@ -213,7 +217,7 @@
 		last = rv
 		return rv
 	}
-	mock := func(from, to *vcsinfo.LongCommit, commits []*vcsinfo.LongCommit, next string) {
+	mock := func(from, to *vcsinfo.LongCommit, commits []*vcsinfo.LongCommit, start, next string) {
 		// Create the mock results.
 		results := &Log{
 			Log:  make([]*Commit, 0, len(commits)),
@@ -239,8 +243,14 @@
 		}
 		js := testutils.MarshalJSON(t, results)
 		js = ")]}'\n" + js
-		urlMock.MockOnce(fmt.Sprintf(LOG_URL, repoUrl, fmt.Sprintf("%s..%s", from.Hash, to.Hash)), mockhttpclient.MockGetDialogue([]byte(js)))
-		urlMock.MockOnce(fmt.Sprintf(LOG_URL, repoUrl, to.Hash), mockhttpclient.MockGetDialogue([]byte(js)))
+		url1 := fmt.Sprintf(LOG_URL, repoUrl, git.LogFromTo(from.Hash, to.Hash))
+		url2 := fmt.Sprintf(LOG_URL, repoUrl, to.Hash)
+		if start != "" {
+			url1 += "&s=" + start
+			url2 += "&s=" + start
+		}
+		urlMock.MockOnce(url1, mockhttpclient.MockGetDialogue([]byte(js)))
+		urlMock.MockOnce(url2, mockhttpclient.MockGetDialogue([]byte(js)))
 	}
 	check := func(from, to *vcsinfo.LongCommit, expectCommits []*vcsinfo.LongCommit) {
 		// The expectations are in chronological order for convenience
@@ -251,7 +261,7 @@
 		sort.Sort(vcsinfo.LongCommitSlice(expect))
 
 		// Test standard Log(from, to) function.
-		log, err := repo.Log(ctx, from.Hash, to.Hash)
+		log, err := repo.Log(ctx, git.LogFromTo(from.Hash, to.Hash))
 		assert.NoError(t, err)
 		deepequal.AssertDeepEqual(t, expect, log)
 
@@ -275,20 +285,20 @@
 	}
 
 	// Most basic test case; no pagination.
-	mock(commits[0], commits[5], commits[1:5], "")
+	mock(commits[0], commits[5], commits[1:5], "", "")
 	check(commits[0], commits[5], commits[1:5])
 
 	// Two pages.
 	split := 5
-	mock(commits[0], commits[len(commits)-1], commits[split:], commits[split].Hash)
-	mock(commits[0], commits[split], commits[1:split], "")
+	mock(commits[0], commits[len(commits)-1], commits[split:], "", commits[split].Hash)
+	mock(commits[0], commits[len(commits)-1], commits[1:split], commits[split].Hash, "")
 	check(commits[0], commits[len(commits)-1], commits[1:])
 
 	// Three pages.
 	split1 := 7
 	split2 := 3
-	mock(commits[0], commits[len(commits)-1], commits[split1:], commits[split1].Hash)
-	mock(commits[0], commits[split1], commits[split2:split1], commits[split2].Hash)
-	mock(commits[0], commits[split2], commits[1:split2], "")
+	mock(commits[0], commits[len(commits)-1], commits[split1:], "", commits[split1].Hash)
+	mock(commits[0], commits[len(commits)-1], commits[split2:split1], commits[split1].Hash, commits[split2].Hash)
+	mock(commits[0], commits[len(commits)-1], commits[1:split2], commits[split2].Hash, "")
 	check(commits[0], commits[len(commits)-1], commits[1:])
 }
diff --git a/go/gitiles/testutils/testutils.go b/go/gitiles/testutils/testutils.go
index 947e1d1..6e5cdd9 100644
--- a/go/gitiles/testutils/testutils.go
+++ b/go/gitiles/testutils/testutils.go
@@ -34,6 +34,10 @@
 	}
 }
 
+func (mr *MockRepo) Empty() bool {
+	return mr.c.Empty()
+}
+
 func (mr *MockRepo) MockReadFile(ctx context.Context, srcPath, ref string) {
 	contents, err := mr.repo.GetFile(ctx, srcPath, ref)
 	assert.NoError(mr.t, err)
@@ -79,18 +83,37 @@
 	mr.c.MockOnce(url, mockhttpclient.MockGetDialogue(b))
 }
 
-func (mr *MockRepo) MockLog(ctx context.Context, from, to string) {
-	revlist, err := mr.repo.RevList(ctx, fmt.Sprintf("%s..%s", from, to))
+func (mr *MockRepo) MockBranches(ctx context.Context) {
+	branches, err := mr.repo.Branches(ctx)
+	assert.NoError(mr.t, err)
+	res := make(gitiles.RefsMap, len(branches))
+	for _, branch := range branches {
+		res[branch.Name] = gitiles.Ref{
+			Value: branch.Head,
+		}
+	}
+	b, err := json.Marshal(res)
+	assert.NoError(mr.t, err)
+	b = append([]byte(")]}'\n"), b...)
+	url := fmt.Sprintf(gitiles.REFS_URL, mr.url)
+	mr.c.MockOnce(url, mockhttpclient.MockGetDialogue(b))
+}
+
+func (mr *MockRepo) MockLog(ctx context.Context, logExpr string, opts ...gitiles.LogOption) {
+	revlist, err := mr.repo.RevList(ctx, logExpr)
 	assert.NoError(mr.t, err)
 	log := &gitiles.Log{
-		Log: []*gitiles.Commit{},
+		Log: make([]*gitiles.Commit, len(revlist)),
 	}
-	for _, hash := range revlist {
-		log.Log = append(log.Log, mr.getCommit(ctx, hash))
+	for idx, hash := range revlist {
+		log.Log[idx] = mr.getCommit(ctx, hash)
 	}
 	b, err := json.Marshal(log)
 	assert.NoError(mr.t, err)
 	b = append([]byte(")]}'\n"), b...)
-	url := fmt.Sprintf(gitiles.LOG_URL, mr.url, fmt.Sprintf("%s..%s", from, to))
+	url := fmt.Sprintf(gitiles.LOG_URL, mr.url, logExpr)
+	for _, opt := range opts {
+		url += "&" + string(opt)
+	}
 	mr.c.MockOnce(url, mockhttpclient.MockGetDialogue(b))
 }