diff --git a/gas/ChangeLog b/gas/ChangeLog
index ffba5c5ae3..d23030ce29 100644
--- a/gas/ChangeLog
+++ b/gas/ChangeLog
@@ -1,3 +1,12 @@
+2007-01-30  Nick Clifton  <nickc@redhat.com>
+
+	* as.c (main): Mark symbols created via the --defsym command line
+	option as volatile so that they can be overridden later on by a
+	.set directive.  This maintains compatibility with the behaviour
+	of earlier versions of the assembler.
+	* doc/as.texinfo (--defsym): Document that the defined symbol's
+	value can be overridden via a .set directive.
+
 2076-01-28  H.J. Lu  <hongjiu.lu@intel.com>
 
 	* config/tc-i386.c (swap_imm_operands): Renamed to ...
diff --git a/gas/as.c b/gas/as.c
index e1bfb86899..39d7c22dfc 100644
--- a/gas/as.c
+++ b/gas/as.c
@@ -1,6 +1,6 @@
 /* as.c - GAS main program.
    Copyright 1987, 1990, 1991, 1992, 1993, 1994, 1995, 1996, 1997, 1998,
-   1999, 2000, 2001, 2002, 2003, 2004, 2005, 2006
+   1999, 2000, 2001, 2002, 2003, 2004, 2005, 2006, 2007
    Free Software Foundation, Inc.
 
    This file is part of GAS, the GNU Assembler.
@@ -1122,6 +1122,11 @@ main (int argc, char ** argv)
 
       sym = symbol_new (defsyms->name, absolute_section, defsyms->value,
 			&zero_address_frag);
+      /* Make symbols defined on the command line volatile, so that they
+	 can be redefined inside a source file.  This makes this assembler's
+	 behaviour compatible with earlier versions, but it may not be
+	 completely intuitive.  */
+      S_SET_VOLATILE (sym);
       symbol_table_insert (sym);
       next = defsyms->next;
       free (defsyms);
diff --git a/gas/doc/as.texinfo b/gas/doc/as.texinfo
index be21112c66..fed4213f05 100644
--- a/gas/doc/as.texinfo
+++ b/gas/doc/as.texinfo
@@ -501,7 +501,9 @@ other assemblers.
 @item --defsym @var{sym}=@var{value}
 Define the symbol @var{sym} to be @var{value} before assembling the input file.
 @var{value} must be an integer constant.  As in C, a leading @samp{0x}
-indicates a hexadecimal value, and a leading @samp{0} indicates an octal value.
+indicates a hexadecimal value, and a leading @samp{0} indicates an octal
+value.  The value of the symbol can be overridden inside a source file via the
+use of a @code{.set} pseudo-op.
 
 @item -f
 ``fast''---skip whitespace and comment preprocessing (assume source is