diff --git a/commit.c b/commit.c
index fc8b4e287d..b6b0e0d6fb 100644
--- a/commit.c
+++ b/commit.c
@@ -250,6 +250,34 @@ void set_commit_buffer(struct commit *commit, void *buffer)
 	commit->buffer = buffer;
 }
 
+const void *get_cached_commit_buffer(const struct commit *commit)
+{
+	return commit->buffer;
+}
+
+const void *get_commit_buffer(const struct commit *commit)
+{
+	const void *ret = get_cached_commit_buffer(commit);
+	if (!ret) {
+		enum object_type type;
+		unsigned long size;
+		ret = read_sha1_file(commit->object.sha1, &type, &size);
+		if (!ret)
+			die("cannot read commit object %s",
+			    sha1_to_hex(commit->object.sha1));
+		if (type != OBJ_COMMIT)
+			die("expected commit for %s, got %s",
+			    sha1_to_hex(commit->object.sha1), typename(type));
+	}
+	return ret;
+}
+
+void unuse_commit_buffer(const struct commit *commit, const void *buffer)
+{
+	if (commit->buffer != buffer)
+		free((void *)buffer);
+}
+
 void free_commit_buffer(struct commit *commit)
 {
 	free(commit->buffer);
diff --git a/commit.h b/commit.h
index cc89128894..259c0aec75 100644
--- a/commit.h
+++ b/commit.h
@@ -57,6 +57,27 @@ void parse_commit_or_die(struct commit *item);
  */
 void set_commit_buffer(struct commit *, void *buffer);
 
+/*
+ * Get any cached object buffer associated with the commit. Returns NULL
+ * if none. The resulting memory should not be freed.
+ */
+const void *get_cached_commit_buffer(const struct commit *);
+
+/*
+ * Get the commit's object contents, either from cache or by reading the object
+ * from disk. The resulting memory should not be modified, and must be given
+ * to unuse_commit_buffer when the caller is done.
+ */
+const void *get_commit_buffer(const struct commit *);
+
+/*
+ * Tell the commit subsytem that we are done with a particular commit buffer.
+ * The commit and buffer should be the input and return value, respectively,
+ * from an earlier call to get_commit_buffer.  The buffer may or may not be
+ * freed by this call; callers should not access the memory afterwards.
+ */
+void unuse_commit_buffer(const struct commit *, const void *buffer);
+
 /*
  * Free any cached object buffer associated with the commit.
  */