diff --git a/builtin-blame.c b/builtin-blame.c
index 114a214ed3..971126a80d 100644
--- a/builtin-blame.c
+++ b/builtin-blame.c
@@ -74,6 +74,7 @@ static unsigned blame_copy_score;
  */
 struct origin {
 	int refcnt;
+	struct origin *previous;
 	struct commit *commit;
 	mmfile_t file;
 	unsigned char blob_sha1[20];
@@ -115,6 +116,8 @@ static inline struct origin *origin_incref(struct origin *o)
 static void origin_decref(struct origin *o)
 {
 	if (o && --o->refcnt <= 0) {
+		if (o->previous)
+			origin_decref(o->previous);
 		free(o->file.ptr);
 		free(o);
 	}
@@ -1198,6 +1201,10 @@ static void pass_blame(struct scoreboard *sb, struct origin *origin, int opt)
 		struct origin *porigin = sg_origin[i];
 		if (!porigin)
 			continue;
+		if (!origin->previous) {
+			origin_incref(porigin);
+			origin->previous = porigin;
+		}
 		if (pass_blame_to_parent(sb, origin, porigin))
 			goto finish;
 	}
@@ -1414,6 +1421,39 @@ static void write_filename_info(const char *path)
 	write_name_quoted(path, stdout, '\n');
 }
 
+/*
+ * Porcelain/Incremental format wants to show a lot of details per
+ * commit.  Instead of repeating this every line, emit it only once,
+ * the first time each commit appears in the output.
+ */
+static int emit_one_suspect_detail(struct origin *suspect)
+{
+	struct commit_info ci;
+
+	if (suspect->commit->object.flags & METAINFO_SHOWN)
+		return 0;
+
+	suspect->commit->object.flags |= METAINFO_SHOWN;
+	get_commit_info(suspect->commit, &ci, 1);
+	printf("author %s\n", ci.author);
+	printf("author-mail %s\n", ci.author_mail);
+	printf("author-time %lu\n", ci.author_time);
+	printf("author-tz %s\n", ci.author_tz);
+	printf("committer %s\n", ci.committer);
+	printf("committer-mail %s\n", ci.committer_mail);
+	printf("committer-time %lu\n", ci.committer_time);
+	printf("committer-tz %s\n", ci.committer_tz);
+	printf("summary %s\n", ci.summary);
+	if (suspect->commit->object.flags & UNINTERESTING)
+		printf("boundary\n");
+	if (suspect->previous) {
+		struct origin *prev = suspect->previous;
+		printf("previous %s ", sha1_to_hex(prev->commit->object.sha1));
+		write_name_quoted(prev->path, stdout, '\n');
+	}
+	return 1;
+}
+
 /*
  * The blame_entry is found to be guilty for the range.  Mark it
  * as such, and show it in incremental output.
@@ -1429,22 +1469,7 @@ static void found_guilty_entry(struct blame_entry *ent)
 		printf("%s %d %d %d\n",
 		       sha1_to_hex(suspect->commit->object.sha1),
 		       ent->s_lno + 1, ent->lno + 1, ent->num_lines);
-		if (!(suspect->commit->object.flags & METAINFO_SHOWN)) {
-			struct commit_info ci;
-			suspect->commit->object.flags |= METAINFO_SHOWN;
-			get_commit_info(suspect->commit, &ci, 1);
-			printf("author %s\n", ci.author);
-			printf("author-mail %s\n", ci.author_mail);
-			printf("author-time %lu\n", ci.author_time);
-			printf("author-tz %s\n", ci.author_tz);
-			printf("committer %s\n", ci.committer);
-			printf("committer-mail %s\n", ci.committer_mail);
-			printf("committer-time %lu\n", ci.committer_time);
-			printf("committer-tz %s\n", ci.committer_tz);
-			printf("summary %s\n", ci.summary);
-			if (suspect->commit->object.flags & UNINTERESTING)
-				printf("boundary\n");
-		}
+		emit_one_suspect_detail(suspect);
 		write_filename_info(suspect->path);
 		maybe_flush_or_die(stdout, "stdout");
 	}
@@ -1551,24 +1576,8 @@ static void emit_porcelain(struct scoreboard *sb, struct blame_entry *ent)
 	       ent->s_lno + 1,
 	       ent->lno + 1,
 	       ent->num_lines);
-	if (!(suspect->commit->object.flags & METAINFO_SHOWN)) {
-		struct commit_info ci;
-		suspect->commit->object.flags |= METAINFO_SHOWN;
-		get_commit_info(suspect->commit, &ci, 1);
-		printf("author %s\n", ci.author);
-		printf("author-mail %s\n", ci.author_mail);
-		printf("author-time %lu\n", ci.author_time);
-		printf("author-tz %s\n", ci.author_tz);
-		printf("committer %s\n", ci.committer);
-		printf("committer-mail %s\n", ci.committer_mail);
-		printf("committer-time %lu\n", ci.committer_time);
-		printf("committer-tz %s\n", ci.committer_tz);
-		write_filename_info(suspect->path);
-		printf("summary %s\n", ci.summary);
-		if (suspect->commit->object.flags & UNINTERESTING)
-			printf("boundary\n");
-	}
-	else if (suspect->commit->object.flags & MORE_THAN_ONE_PATH)
+	if (emit_one_suspect_detail(suspect) ||
+	    (suspect->commit->object.flags & MORE_THAN_ONE_PATH))
 		write_filename_info(suspect->path);
 
 	cp = nth_line(sb, ent->lno);
@@ -1806,36 +1815,6 @@ static void sanity_check_refcnt(struct scoreboard *sb)
 			baa = 1;
 		}
 	}
-	for (ent = sb->ent; ent; ent = ent->next) {
-		/* Mark the ones that haven't been checked */
-		if (0 < ent->suspect->refcnt)
-			ent->suspect->refcnt = -ent->suspect->refcnt;
-	}
-	for (ent = sb->ent; ent; ent = ent->next) {
-		/*
-		 * ... then pick each and see if they have the the
-		 * correct refcnt.
-		 */
-		int found;
-		struct blame_entry *e;
-		struct origin *suspect = ent->suspect;
-
-		if (0 < suspect->refcnt)
-			continue;
-		suspect->refcnt = -suspect->refcnt; /* Unmark */
-		for (found = 0, e = sb->ent; e; e = e->next) {
-			if (e->suspect != suspect)
-				continue;
-			found++;
-		}
-		if (suspect->refcnt != found) {
-			fprintf(stderr, "%s in %s has refcnt %d, not %d\n",
-				ent->suspect->path,
-				sha1_to_hex(ent->suspect->commit->object.sha1),
-				ent->suspect->refcnt, found);
-			baa = 2;
-		}
-	}
 	if (baa) {
 		int opt = 0160;
 		find_alignment(sb, &opt);