--- ccache.c.orig	2013-01-06 17:57:59.000000000 +0100
+++ ccache.c	2013-10-18 10:35:32.266543168 +0200
@@ -942,6 +942,13 @@ calculate_object_hash(struct args *args,
 			continue;
 		}
 
+		if (str_startswith(args->argv[i], "-fdebug-prefix-map=")) {
+			/* The -fdebug-prefix-map may be used with CCACHE_BASEDIR to reuse
+			   compilation objects across multiple branches compiled in different
+			   directories. Skip it from hashing. */
+			continue;
+		}
+
 		/* When using the preprocessor, some arguments don't contribute
 		   to the hash. The theory is that these arguments will change
 		   the output of -E if they are going to have any effect at