Index: configure.ac
===================================================================
--- configure.ac	(revision 221318)
+++ configure.ac	(working copy)
@@ -3623,6 +3623,18 @@ [	.set nomacro
   [Define if your assembler supports the lituse_jsrdirect relocation.])])
     ;;
 
+  avr-*-*)
+    gcc_GAS_CHECK_FEATURE([--mlink-relax option], gcc_cv_as_avr_mlink_relax,,
+      [--mlink-relax], [.text],,
+      [AC_DEFINE(HAVE_AS_AVR_MLINK_RELAX_OPTION, 1,
+		[Define if your assembler supports --mlink-relax option.])])
+
+    gcc_GAS_CHECK_FEATURE([-mrmw option], gcc_cv_as_avr_mrmw,,
+      [-mrmw], [.text],,
+      [AC_DEFINE(HAVE_AS_AVR_MRMW_OPTION, 1,
+		[Define if your assembler supports -mrmw option.])])
+    ;;
+
   cris-*-*)
     gcc_GAS_CHECK_FEATURE([-no-mul-bug-abort option],
       gcc_cv_as_cris_no_mul_bug,[2,15,91],
Index: configure
===================================================================
--- configure	(revision 221318)
+++ configure	(working copy)
@@ -24185,6 +24185,70 @@ $as_echo "#define HAVE_AS_JSRDIRECT_RELO
 fi
     ;;
 
+  avr-*-*)
+    { $as_echo "$as_me:${as_lineno-$LINENO}: checking assembler for --mlink-relax option" >&5
+$as_echo_n "checking assembler for --mlink-relax option... " >&6; }
+if test "${gcc_cv_as_avr_mlink_relax+set}" = set; then :
+  $as_echo_n "(cached) " >&6
+else
+  gcc_cv_as_avr_mlink_relax=no
+  if test x$gcc_cv_as != x; then
+    $as_echo '.text' > conftest.s
+    if { ac_try='$gcc_cv_as $gcc_cv_as_flags --mlink-relax -o conftest.o conftest.s >&5'
+  { { eval echo "\"\$as_me\":${as_lineno-$LINENO}: \"$ac_try\""; } >&5
+  (eval $ac_try) 2>&5
+  ac_status=$?
+  $as_echo "$as_me:${as_lineno-$LINENO}: \$? = $ac_status" >&5
+  test $ac_status = 0; }; }
+    then
+	gcc_cv_as_avr_mlink_relax=yes
+    else
+      echo "configure: failed program was" >&5
+      cat conftest.s >&5
+    fi
+    rm -f conftest.o conftest.s
+  fi
+fi
+{ $as_echo "$as_me:${as_lineno-$LINENO}: result: $gcc_cv_as_avr_mlink_relax" >&5
+$as_echo "$gcc_cv_as_avr_mlink_relax" >&6; }
+if test $gcc_cv_as_avr_mlink_relax = yes; then
+
+$as_echo "#define HAVE_AS_AVR_MLINK_RELAX_OPTION 1" >>confdefs.h
+
+fi
+
+    { $as_echo "$as_me:${as_lineno-$LINENO}: checking assembler for -mrmw option" >&5
+$as_echo_n "checking assembler for -mrmw option... " >&6; }
+if test "${gcc_cv_as_avr_mrmw+set}" = set; then :
+  $as_echo_n "(cached) " >&6
+else
+  gcc_cv_as_avr_mrmw=no
+  if test x$gcc_cv_as != x; then
+    $as_echo '.text' > conftest.s
+    if { ac_try='$gcc_cv_as $gcc_cv_as_flags -mrmw -o conftest.o conftest.s >&5'
+  { { eval echo "\"\$as_me\":${as_lineno-$LINENO}: \"$ac_try\""; } >&5
+  (eval $ac_try) 2>&5
+  ac_status=$?
+  $as_echo "$as_me:${as_lineno-$LINENO}: \$? = $ac_status" >&5
+  test $ac_status = 0; }; }
+    then
+	gcc_cv_as_avr_mrmw=yes
+    else
+      echo "configure: failed program was" >&5
+      cat conftest.s >&5
+    fi
+    rm -f conftest.o conftest.s
+  fi
+fi
+{ $as_echo "$as_me:${as_lineno-$LINENO}: result: $gcc_cv_as_avr_mrmw" >&5
+$as_echo "$gcc_cv_as_avr_mrmw" >&6; }
+if test $gcc_cv_as_avr_mrmw = yes; then
+
+$as_echo "#define HAVE_AS_AVR_MRMW_OPTION 1" >>confdefs.h
+
+fi
+    ;;
+
   cris-*-*)
     { $as_echo "$as_me:${as_lineno-$LINENO}: checking assembler for -no-mul-bug-abort option" >&5
 $as_echo_n "checking assembler for -no-mul-bug-abort option... " >&6; }
Index: config.in
===================================================================
--- config.in	(revision 221321)
+++ config.in	(working copy)
@@ -247,6 +247,18 @@ that are supported for each access macro
 #endif
 
 
+/* Define if your assembler supports --mlink-relax option. */
+#ifndef USED_FOR_TARGET
+#undef HAVE_AS_AVR_MLINK_RELAX_OPTION
+#endif
+
+
+/* Define if your assembler supports -mrmw option. */
+#ifndef USED_FOR_TARGET
+#undef HAVE_AS_AVR_MRMW_OPTION
+#endif
+
+
 /* Define if your assembler supports cmpb. */
 #ifndef USED_FOR_TARGET
 #undef HAVE_AS_CMPB
Index: config/avr/gen-avr-mmcu-specs.c
===================================================================
--- config/avr/gen-avr-mmcu-specs.c	(revision 221316)
+++ config/avr/gen-avr-mmcu-specs.c	(working copy)
@@ -21,6 +21,8 @@
 #include <stdio.h>
 #include <string.h>
 
+#include "config.h"
+
 #define IN_GEN_AVR_MMCU_TEXI
 
 #include "avr-devices.c"
@@ -155,11 +157,15 @@ bool is_arch = NULL == mcu->macro;
 
   fprintf (f, "*asm_arch:\n\t-mmcu=%s\n\n", arch->name);
 
+#ifdef HAVE_AS_AVR_MLINK_RELAX_OPTION                   \
   fprintf (f, "*asm_relax:\n\t%s\n\n", ASM_RELAX_SPEC);
+#endif // have as --mlink-relax
 
+#ifdef HAVE_AS_AVR_MRMW_OPTION
   fprintf (f, "*asm_rmw:\n%s\n\n", rmw
            ? "\t%{!mno-rmw: -mrmw}"
            : "\t%{mrmw}");
+#endif // have as -mrmw
 
   fprintf (f, "*asm_errata_skip:\n%s\n\n", errata_skip
            ? "\t%{mno-skip-bug}"