diff --git a/gerrit/gerrit.go b/gerrit/gerrit.go
index e62dadc..d2914c4 100644
--- a/gerrit/gerrit.go
+++ b/gerrit/gerrit.go
@@ -61,6 +61,10 @@
 // It is only for use with errors.Is.
 var ErrResourceNotExist = errors.New("gerrit: requested resource does not exist")
 
+// ErrNotModified is returned when a modification didn't result in any change.
+// It is only for use with errors.Is. Not all APIs return this error; check the documentation.
+var ErrNotModified = errors.New("gerrit: requested modification resulted in no change")
+
 // HTTPError is the error type returned when a Gerrit API call does not return
 // the expected status.
 type HTTPError struct {
@@ -74,7 +78,17 @@
 }
 
 func (e *HTTPError) Is(target error) bool {
-	return target == ErrResourceNotExist && e.Res.StatusCode == http.StatusNotFound
+	switch target {
+	case ErrResourceNotExist:
+		return e.Res.StatusCode == http.StatusNotFound
+	case ErrNotModified:
+		// As of writing, this error text is the only way to distinguish different Conflict errors. See
+		// https://cs.opensource.google/gerrit/gerrit/gerrit/+/master:java/com/google/gerrit/server/restapi/change/ChangeEdits.java;l=346;drc=d338da307a518f7f28b94310c1c083c997ca3c6a
+		// https://cs.opensource.google/gerrit/gerrit/gerrit/+/master:java/com/google/gerrit/server/edit/ChangeEditModifier.java;l=453;drc=3bc970bb3e689d1d340382c3f5e5285d44f91dbf
+		return e.Res.StatusCode == http.StatusConflict && bytes.Contains(e.Body, []byte("no changes were made"))
+	default:
+		return false
+	}
 }
 
 // doArg is an optional argument for the Client.do method.
@@ -750,21 +764,16 @@
 }
 
 // ChangeFileContentInChangeEdit puts content of a file to a change edit.
+// If no change is made, an error that matches ErrNotModified is returned.
 //
 // See https://gerrit-review.googlesource.com/Documentation/rest-api-changes.html#put-edit-file.
 func (c *Client) ChangeFileContentInChangeEdit(ctx context.Context, changeID string, path string, content string) error {
-	err := c.do(ctx, nil, "PUT", "/changes/"+changeID+"/edit/"+url.QueryEscape(path),
+	return c.do(ctx, nil, "PUT", "/changes/"+changeID+"/edit/"+url.QueryEscape(path),
 		reqBodyRaw{strings.NewReader(content)}, wantResStatus(http.StatusNoContent))
-	if he, ok := err.(*HTTPError); ok && he.Res.StatusCode == http.StatusConflict {
-		// The change edit was a no-op.
-		// Note: If/when there's a need inside x/build to handle this differently,
-		// maybe it'll be a good time to return something other than a *HTTPError
-		// and document it as part of the API.
-	}
-	return err
 }
 
 // DeleteFileInChangeEdit deletes a file from a change edit.
+// If no change is made, an error that matches ErrNotModified is returned.
 //
 // See https://gerrit-review.googlesource.com/Documentation/rest-api-changes.html#delete-edit-file.
 func (c *Client) DeleteFileInChangeEdit(ctx context.Context, changeID string, path string) error {
diff --git a/internal/relui/workflows.go b/internal/relui/workflows.go
index c1eb400..aa57775 100644
--- a/internal/relui/workflows.go
+++ b/internal/relui/workflows.go
@@ -297,7 +297,7 @@
 		branch = "master"
 	}
 	branchVal := wd.Constant(branch)
-	branchHead := wd.Task("Read branch HEAD", version.ReadBranchHead, branchVal)
+	releaseBase := wd.Task("Pick release base commit", version.ReadBranchHead, branchVal)
 
 	// Select version, check milestones.
 	nextVersion := wd.Task("Get next version", version.GetNextVersion, kindVal)
@@ -308,7 +308,7 @@
 	wd.Output("Download CL submitted", dlclCommit)
 
 	// Build, test, and sign release.
-	signedAndTestedArtifacts, err := build.addBuildTasks(wd, "go1.19", nextVersion, branchHead, skipTests, checked)
+	signedAndTestedArtifacts, err := build.addBuildTasks(wd, "go1.19", nextVersion, releaseBase, skipTests, checked)
 	if err != nil {
 		return err
 	}
@@ -319,11 +319,11 @@
 	// Tag version and upload to CDN/website.
 	uploaded := wd.Action("Upload artifacts to CDN", build.uploadArtifacts, signedAndTestedArtifacts, verified)
 
-	tagCommit := branchHead
+	tagCommit := releaseBase
 	if branch != "master" {
-		branchHeadChecked := wd.Action("Check for modified branch head", version.CheckBranchHead, branchVal, branchHead, uploaded)
+		branchHeadChecked := wd.Action("Check for modified branch head", version.CheckBranchHead, branchVal, releaseBase, uploaded)
 		versionCL := wd.Task("Mail version CL", version.CreateAutoSubmitVersionCL, branchVal, nextVersion, branchHeadChecked)
-		tagCommit = wd.Task("Wait for version CL submission", version.AwaitCL, versionCL, branchHead)
+		tagCommit = wd.Task("Wait for version CL submission", version.AwaitCL, versionCL, releaseBase)
 	}
 	tagged := wd.Action("Tag version", version.TagRelease, nextVersion, tagCommit, uploaded)
 
diff --git a/internal/task/gerrit.go b/internal/task/gerrit.go
index 21d7ec5..2f9f825 100644
--- a/internal/task/gerrit.go
+++ b/internal/task/gerrit.go
@@ -11,9 +11,11 @@
 )
 
 type GerritClient interface {
-	// CreateAutoSubmitChange creates a change with the given metadata and contents, sets
-	// Run-TryBots and Auto-Submit, and returns its change ID.
+	// CreateAutoSubmitChange creates a change with the given metadata and
+	// contents, sets Run-TryBots and Auto-Submit, and returns its change ID.
 	// If the content of a file is empty, that file will be deleted from the repository.
+	// If the requested contents match the state of the repository, no change
+	// is created and the returned change ID will be empty.
 	CreateAutoSubmitChange(ctx context.Context, input gerrit.ChangeInput, contents map[string]string) (string, error)
 	// AwaitSubmit waits for the specified change to be auto-submitted or fail
 	// trybots. If the CL is submitted, returns the submitted commit hash.
@@ -37,16 +39,27 @@
 		return "", err
 	}
 	changeID := fmt.Sprintf("%s~%d", change.Project, change.ChangeNumber)
+	anyChange := false
 	for path, content := range files {
+		var err error
 		if content == "" {
-			if err := c.Client.DeleteFileInChangeEdit(ctx, changeID, path); err != nil {
-				return "", err
-			}
+			err = c.Client.DeleteFileInChangeEdit(ctx, changeID, path)
 		} else {
-			if err := c.Client.ChangeFileContentInChangeEdit(ctx, changeID, path, content); err != nil {
-				return "", err
-			}
+			err = c.Client.ChangeFileContentInChangeEdit(ctx, changeID, path, content)
 		}
+		if errors.Is(err, gerrit.ErrNotModified) {
+			continue
+		}
+		if err != nil {
+			return "", err
+		}
+		anyChange = true
+	}
+	if !anyChange {
+		if err := c.Client.AbandonChange(ctx, changeID, "no changes necessary"); err != nil {
+			return "", err
+		}
+		return "", nil
 	}
 
 	if err := c.Client.PublishChangeEdit(ctx, changeID); err != nil {
diff --git a/internal/task/version.go b/internal/task/version.go
index 1bc01b8..d02ccae 100644
--- a/internal/task/version.go
+++ b/internal/task/version.go
@@ -84,8 +84,17 @@
 	})
 }
 
-// AwaitCL waits for the specified CL to be submitted.
+// AwaitCL waits for the specified CL to be submitted, and returns the new
+// branch head. Callers can pass baseCommit, the current branch head, to verify
+// that no CLs were submitted between when the CL was created and when it was
+// merged. If changeID is blank because the intended CL was a no-op, baseCommit
+// is returned immediately.
 func (t *VersionTasks) AwaitCL(ctx *workflow.TaskContext, changeID, baseCommit string) (string, error) {
+	if changeID == "" {
+		ctx.Printf("No CL was necessary")
+		return baseCommit, nil
+	}
+
 	ctx.Printf("Awaiting review/submit of %v", ChangeLink(changeID))
 	return t.Gerrit.AwaitSubmit(ctx, changeID, baseCommit)
 }