diff --git a/builtin/log.c b/builtin/log.c
index b50ef7510c..a491d3dea0 100644
--- a/builtin/log.c
+++ b/builtin/log.c
@@ -342,8 +342,7 @@ static int cmd_log_walk(struct rev_info *rev)
 	 * retain that state information if replacing rev->diffopt in this loop
 	 */
 	while ((commit = get_revision(rev)) != NULL) {
-		if (!log_tree_commit(rev, commit) &&
-		    rev->max_count >= 0)
+		if (!log_tree_commit(rev, commit) && rev->max_count >= 0)
 			/*
 			 * We decremented max_count in get_revision,
 			 * but we didn't actually show the commit.
@@ -504,7 +503,8 @@ static int show_tree_object(const unsigned char *sha1,
 	return 0;
 }
 
-static void show_rev_tweak_rev(struct rev_info *rev, struct setup_revision_opt *opt)
+static void show_setup_revisions_tweak(struct rev_info *rev,
+				       struct setup_revision_opt *opt)
 {
 	if (rev->ignore_merges) {
 		/* There was no "-m" on the command line */
@@ -539,7 +539,7 @@ int cmd_show(int argc, const char **argv, const char *prefix)
 
 	memset(&opt, 0, sizeof(opt));
 	opt.def = "HEAD";
-	opt.tweak = show_rev_tweak_rev;
+	opt.tweak = show_setup_revisions_tweak;
 	cmd_log_init(argc, argv, prefix, &rev, &opt);
 
 	if (!rev.no_walk)
@@ -626,12 +626,20 @@ int cmd_log_reflog(int argc, const char **argv, const char *prefix)
 	return cmd_log_walk(&rev);
 }
 
-static void default_follow_tweak(struct rev_info *rev,
-				 struct setup_revision_opt *opt)
+static void log_setup_revisions_tweak(struct rev_info *rev,
+				      struct setup_revision_opt *opt)
 {
 	if (DIFF_OPT_TST(&rev->diffopt, DEFAULT_FOLLOW_RENAMES) &&
 	    rev->prune_data.nr == 1)
 		DIFF_OPT_SET(&rev->diffopt, FOLLOW_RENAMES);
+
+	/* Turn --cc/-c into -p --cc/-c when -p was not given */
+	if (!rev->diffopt.output_format && rev->combine_merges)
+		rev->diffopt.output_format = DIFF_FORMAT_PATCH;
+
+	/* Turn -m on when --cc/-c was given */
+	if (rev->combine_merges)
+		rev->ignore_merges = 0;
 }
 
 int cmd_log(int argc, const char **argv, const char *prefix)
@@ -647,7 +655,7 @@ int cmd_log(int argc, const char **argv, const char *prefix)
 	memset(&opt, 0, sizeof(opt));
 	opt.def = "HEAD";
 	opt.revarg_opt = REVARG_COMMITTISH;
-	opt.tweak = default_follow_tweak;
+	opt.tweak = log_setup_revisions_tweak;
 	cmd_log_init(argc, argv, prefix, &rev, &opt);
 	return cmd_log_walk(&rev);
 }
@@ -1455,8 +1463,7 @@ int cmd_format_patch(int argc, const char **argv, const char *prefix)
 			continue;
 		}
 
-		if (ignore_if_in_upstream &&
-				has_commit_patch_id(commit, &ids))
+		if (ignore_if_in_upstream && has_commit_patch_id(commit, &ids))
 			continue;
 
 		nr++;