diff --git a/config/autoconf.mk.in b/config/autoconf.mk.in
index a2e60fc3e30..d3eb8e85239 100644
--- a/config/autoconf.mk.in
+++ b/config/autoconf.mk.in
@@ -298,6 +298,7 @@ WARNINGS_AS_ERRORS = @WARNINGS_AS_ERRORS@
 MOZ_OPTIMIZE	= @MOZ_OPTIMIZE@
 MOZ_OPTIMIZE_FLAGS = @MOZ_OPTIMIZE_FLAGS@
 MOZ_OPTIMIZE_LDFLAGS = @MOZ_OPTIMIZE_LDFLAGS@
+MOZ_OPTIMIZE_SIZE_TWEAK = @MOZ_OPTIMIZE_SIZE_TWEAK@
 
 MOZ_RTTI_FLAGS_ON = @_MOZ_RTTI_FLAGS_ON@
 MOZ_EXCEPTIONS_FLAGS_ON = @_MOZ_EXCEPTIONS_FLAGS_ON@
diff --git a/configure.in b/configure.in
index 9f01855f956..ec747afca06 100644
--- a/configure.in
+++ b/configure.in
@@ -2188,7 +2188,12 @@ ia64*-hpux*)
         MOZ_DEBUG_FLAGS="-g"
     elif test "$GNU_CC" -o "$GNU_CXX"; then
         GCC_VERSION=`$CC -v 2>&1 | awk '/^gcc version/ { print $3 }'`
-        MOZ_OPTIMIZE_FLAGS="-O3 -fomit-frame-pointer"
+        case $GCC_VERSION in
+        4.1.*|4.2.*|4.5.*)
+            # -Os is broken on gcc 4.1.x 4.2.x, 4.5.x we need to tweak it to get good results.
+            MOZ_OPTIMIZE_SIZE_TWEAK="-finline-limit=50"
+        esac
+        MOZ_OPTIMIZE_FLAGS="-Os -freorder-blocks -fomit-frame-pointer $MOZ_OPTIMIZE_SIZE_TWEAK"
         MOZ_DEBUG_FLAGS="-g"
     fi
 
@@ -7117,6 +7122,7 @@ fi # COMPILE_ENVIRONMENT
 AC_SUBST(MOZ_OPTIMIZE)
 AC_SUBST(MOZ_OPTIMIZE_FLAGS)
 AC_SUBST(MOZ_OPTIMIZE_LDFLAGS)
+AC_SUBST(MOZ_OPTIMIZE_SIZE_TWEAK)
 
 dnl ========================================================
 dnl = (Deprecated) generation of debugger info for specific modules
diff --git a/js/src/Makefile.in b/js/src/Makefile.in
index 069cc2d11e7..1a61d3bdd86 100644
--- a/js/src/Makefile.in
+++ b/js/src/Makefile.in
@@ -88,7 +88,7 @@ MODULE_OPTIMIZE_FLAGS = -O2 -ip
 #XXX: do we want different INTERP_OPTIMIZER flags here?
 endif
 else # not INTEL_CXX
-MODULE_OPTIMIZE_FLAGS = -O3 -fstrict-aliasing -fomit-frame-pointer
+MODULE_OPTIMIZE_FLAGS = -O3 -fstrict-aliasing -fomit-frame-pointer $(MOZ_OPTIMIZE_SIZE_TWEAK)
 # Special optimization flags for jsinterp.c
 INTERP_OPTIMIZER = -O3 -fstrict-aliasing
 endif
diff --git a/js/src/config/autoconf.mk.in b/js/src/config/autoconf.mk.in
index 5f6945b7afc..5f9103e2b48 100644
--- a/js/src/config/autoconf.mk.in
+++ b/js/src/config/autoconf.mk.in
@@ -146,6 +146,7 @@ WARNINGS_AS_ERRORS = @WARNINGS_AS_ERRORS@
 MOZ_OPTIMIZE	= @MOZ_OPTIMIZE@
 MOZ_OPTIMIZE_FLAGS = @MOZ_OPTIMIZE_FLAGS@
 MOZ_OPTIMIZE_LDFLAGS = @MOZ_OPTIMIZE_LDFLAGS@
+MOZ_OPTIMIZE_SIZE_TWEAK = @MOZ_OPTIMIZE_SIZE_TWEAK@
 
 MOZ_RTTI_FLAGS_ON = @_MOZ_RTTI_FLAGS_ON@
 MOZ_EXCEPTIONS_FLAGS_ON = @_MOZ_EXCEPTIONS_FLAGS_ON@
diff --git a/js/src/configure.in b/js/src/configure.in
index e1be8a25263..a280c28b059 100644
--- a/js/src/configure.in
+++ b/js/src/configure.in
@@ -1880,7 +1880,12 @@ ia64*-hpux*)
         MOZ_DEBUG_FLAGS="-g"
     elif test "$GNU_CXX"; then
         GCC_VERSION=`$CXX -v 2>&1 | awk '/^gcc version/ { print $3 }'`
-        MOZ_OPTIMIZE_FLAGS="-O3 -fomit-frame-pointer"
+        case $GCC_VERSION in
+        4.1.*|4.2.*|4.5.*)
+            # -Os is broken on gcc 4.1.x 4.2.x, 4.5.x we need to tweak it to get good results.
+            MOZ_OPTIMIZE_SIZE_TWEAK="-finline-limit=50"
+        esac
+        MOZ_OPTIMIZE_FLAGS="-Os -freorder-blocks -fno-reorder-functions -fomit-frame-pointer $MOZ_OPTIMIZE_SIZE_TWEAK"
         MOZ_DEBUG_FLAGS="-g"
     fi
 
@@ -4193,6 +4198,7 @@ fi # COMPILE_ENVIRONMENT
 AC_SUBST(MOZ_OPTIMIZE)
 AC_SUBST(MOZ_OPTIMIZE_FLAGS)
 AC_SUBST(MOZ_OPTIMIZE_LDFLAGS)
+AC_SUBST(MOZ_OPTIMIZE_SIZE_TWEAK)
 
 dnl ========================================================
 dnl = (Deprecated) generation of debugger info for specific modules
diff --git a/xpcom/io/Makefile.in b/xpcom/io/Makefile.in
index 3d7751b8bad..baa53d0e20a 100644
--- a/xpcom/io/Makefile.in
+++ b/xpcom/io/Makefile.in
@@ -51,7 +51,7 @@ MOZILLA_INTERNAL_API = 1
 # work around bug 408258
 ifdef GNU_CC 
 ifneq ($(OS_ARCH), Darwin)
-MODULE_OPTIMIZE_FLAGS = -Os -fno-strict-aliasing
+MODULE_OPTIMIZE_FLAGS = -Os -fno-strict-aliasing $(MOZ_OPTIMIZE_SIZE_TWEAK)
 endif
 endif