diff --git a/Documentation/git-cat-file.txt b/Documentation/git-cat-file.txt
index 48fb37769c..2131a29993 100644
--- a/Documentation/git-cat-file.txt
+++ b/Documentation/git-cat-file.txt
@@ -9,12 +9,13 @@ git-cat-file - Provide content or type information for repository objects
 
 SYNOPSIS
 --------
-'git-cat-file' (-t | <type>) <object>
+'git-cat-file' (-t | -s | <type>) <object>
 
 DESCRIPTION
 -----------
 Provides content or type of objects in the repository. The type
-is required if '-t' is not being used to find the object type.
+is required unless '-t' is used to find the object type,
+or '-s' is used to find the object size.
 
 OPTIONS
 -------
@@ -25,6 +26,10 @@ OPTIONS
 	Instead of the content, show the object type identified by
 	<object>.
 
+-s::
+	Instead of the content, show the object size identified by
+	<object>.
+
 <type>::
 	Typically this matches the real type of <object> but asking
 	for a type that can trivially dereferenced from the given
@@ -35,7 +40,8 @@ OPTIONS
 
 OUTPUT
 ------
-If '-t' is specified, one of the <type>.
+If '-t' is specified, one of the <type>.  If '-s' is specified,
+the size of the <object> in bytes.
 
 Otherwise the raw (though uncompressed) contents of the <object> will
 be returned.
diff --git a/cat-file.c b/cat-file.c
index 0076fc5b20..85a5d4caed 100644
--- a/cat-file.c
+++ b/cat-file.c
@@ -13,11 +13,18 @@ int main(int argc, char **argv)
 	unsigned long size;
 
 	if (argc != 3 || get_sha1(argv[2], sha1))
-		usage("git-cat-file [-t | tagname] <sha1>");
+		usage("git-cat-file [-t | -s | tagname] <sha1>");
 
-	if (!strcmp("-t", argv[1])) {
+	if (!strcmp("-t", argv[1]) || !strcmp("-s", argv[1])) {
 		if (!sha1_object_info(sha1, type, &size)) {
-			printf("%s\n", type);
+			switch (argv[1][1]) {
+			case 't':
+				printf("%s\n", type);
+				break;
+			case 's':
+				printf("%lu\n", size);
+				break;
+			}
 			return 0;
 		}
 		buf = NULL;