diff --git a/config/autoconf.mk.in b/config/autoconf.mk.in
index 3d948fb9b09..72df00d7df4 100644
--- a/config/autoconf.mk.in
+++ b/config/autoconf.mk.in
@@ -308,6 +308,7 @@ 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 317cb1f7320..6151b59af3c 100644
--- a/configure.in
+++ b/configure.in
@@ -2206,9 +2206,9 @@ ia64*-hpux*)
         esac
         # If we're building with --enable-profiling, we need a frame pointer.
         if test -z "$MOZ_PROFILING"; then
-            MOZ_OPTIMIZE_FLAGS="-O3 -fomit-frame-pointer"
+            MOZ_OPTIMIZE_FLAGS="-Os -freorder-blocks -fomit-frame-pointer $MOZ_OPTIMIZE_SIZE_TWEAK"
         else
-            MOZ_OPTIMIZE_FLAGS="-O3 -fno-omit-frame-pointer"
+            MOZ_OPTIMIZE_FLAGS="-Os -freorder-blocks -fno-omit-frame-pointer $MOZ_OPTIMIZE_SIZE_TWEAK"
         fi
         MOZ_DEBUG_FLAGS="-g"
     fi
@@ -7224,6 +7224,7 @@ 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/config/autoconf.mk.in b/js/src/config/autoconf.mk.in
index 8eb00acfb51..28c3ea06968 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 00dd391c406..a71e2b93d78 100644
--- a/js/src/configure.in
+++ b/js/src/configure.in
@@ -1899,9 +1899,9 @@ ia64*-hpux*)
         esac
         # If we're building with --enable-profiling, we need a frame pointer.
         if test -z "$MOZ_PROFILING"; then
-          MOZ_OPTIMIZE_FLAGS="-O3 -fomit-frame-pointer"
+          MOZ_OPTIMIZE_FLAGS="-Os -freorder-blocks -fno-reorder-functions -fomit-frame-pointer $MOZ_OPTIMIZE_SIZE_TWEAK"
         else
-          MOZ_OPTIMIZE_FLAGS="-Os -fno-omit-frame-pointer"
+          MOZ_OPTIMIZE_FLAGS="-Os -freorder-blocks -fno-reorder-functions -fno-omit-frame-pointer $MOZ_OPTIMIZE_SIZE_TWEAK"
         fi
         MOZ_DEBUG_FLAGS="-g"
     fi
@@ -4272,6 +4272,7 @@ 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/layout/reftests/css-calc/border-radius-1-ref.html b/layout/reftests/css-calc/border-radius-1-ref.html
index e5de63e6c6e..a8463c3f251 100644
--- a/layout/reftests/css-calc/border-radius-1-ref.html
+++ b/layout/reftests/css-calc/border-radius-1-ref.html
@@ -3,10 +3,10 @@
 <style>
 
 p {
-  height: 256px;
-  width: 512px;
+  height: 200px;
+  width: 400px;
   background: blue;
-  border-radius: 21px 6px 12px 29px / 5px 16px 10px 3px;
+  border-radius: 13px 14px 14px 5px / 3px 2px 10px 3px;
 }
 
 </style>
diff --git a/layout/reftests/css-calc/border-radius-1.html b/layout/reftests/css-calc/border-radius-1.html
index 16af05680ac..6726cb50649 100644
--- a/layout/reftests/css-calc/border-radius-1.html
+++ b/layout/reftests/css-calc/border-radius-1.html
@@ -3,20 +3,10 @@
 <style>
 
 p {
-  /* We use powers of two here to avoid floating-point issues.
-     See bug 590181. */
-
-  height: 256px;
-  width: 512px;
+  height: 200px;
+  width: 400px;
   background: blue;
-  border-radius: -moz-calc((1/32 * 100%) + 5px)
-                 -moz-calc((1/64 * 100%) - 2px)
-                 -moz-calc(10px + (1/256 * 100%))
-                 -moz-calc((1/16 * 100%) - 3px) /
-                 -moz-calc((1/32 * 100%) - (1px + (1/128 * 100%)))
-                 -moz-calc(1/16 * 100%)
-                 -moz-calc(10px)
-                 3px;
+  border-radius: -moz-calc(2% + 5px) -moz-calc(4% - 2px) -moz-calc(10px + 1%) -moz-calc(2% - 3px) / -moz-calc(3% - (1px + 1%)) -moz-calc(1%) -moz-calc(10px) 3px;
 }
 
 </style>
diff --git a/layout/style/test/test_transitions_per_property.html b/layout/style/test/test_transitions_per_property.html
index 1846ba47f7a..dab7bc13f75 100644
--- a/layout/style/test/test_transitions_per_property.html
+++ b/layout/style/test/test_transitions_per_property.html
@@ -553,10 +553,8 @@ function test_radius_transition(prop) {
 
   // FIXME: Test a square for now, since we haven't updated to the spec
   // for vertical components being relative to the height.
-  // Note: We use powers of two here so the floating-point math comes out
-  // nicely.
-  div.style.setProperty("width", "256px", "");
-  div.style.setProperty("height", "256px", "");
+  div.style.setProperty("width", "200px", "");
+  div.style.setProperty("height", "200px", "");
   div.style.setProperty("border", "none", "");
   div.style.setProperty("padding", "0", "");
 
@@ -570,14 +568,14 @@ function test_radius_transition(prop) {
      "radius-valued property " + prop + ": interpolation of radius");
   check_distance(prop, "3px", "6px", "15px");
   div.style.setProperty("-moz-transition-property", "none", "");
-  div.style.setProperty(prop, "12.5%", "");
-  is(cs.getPropertyValue(prop), "32px",
+  div.style.setProperty(prop, "5%", "");
+  is(cs.getPropertyValue(prop), "10px",
      "radius-valued property " + prop + ": computed value before transition");
   div.style.setProperty("-moz-transition-property", prop, "");
   div.style.setProperty(prop, "25%", "");
-  is(cs.getPropertyValue(prop), "40px",
+  is(cs.getPropertyValue(prop), "20px",
      "radius-valued property " + prop + ": interpolation of radius");
-  check_distance(prop, "12.5%", "15.625%", "25%");
+  check_distance(prop, "5%", "10%", "25%");
   div.style.setProperty("-moz-transition-property", "none", "");
   div.style.setProperty(prop, "3px 8px", "");
   is(cs.getPropertyValue(prop), "3px 8px",
@@ -588,21 +586,21 @@ function test_radius_transition(prop) {
      "radius-valued property " + prop + ": interpolation of radius");
   check_distance(prop, "3px 8px", "6px 9px", "15px 12px");
   div.style.setProperty("-moz-transition-property", "none", "");
-  div.style.setProperty(prop, "12.5% 6.25%", "");
-  is(cs.getPropertyValue(prop), "32px 16px",
+  div.style.setProperty(prop, "5% 15%", "");
+  is(cs.getPropertyValue(prop), "10px 30px",
      "radius-valued property " + prop + ": computed value before transition");
   div.style.setProperty("-moz-transition-property", prop, "");
   div.style.setProperty(prop, "25%", "");
-  is(cs.getPropertyValue(prop), "40px 28px",
+  is(cs.getPropertyValue(prop), "20px 35px",
      "radius-valued property " + prop + ": interpolation of radius");
   check_distance(prop, "5% 15%", "10% 17.5%", "25%");
   div.style.setProperty("-moz-transition-property", "none", "");
-  div.style.setProperty(prop, "6.25% 12.5%", "");
-  is(cs.getPropertyValue(prop), "16px 32px",
+  div.style.setProperty(prop, "8% 12%", "");
+  is(cs.getPropertyValue(prop), "16px 24px",
      "radius-valued property " + prop + ": computed value before transition");
   div.style.setProperty("-moz-transition-property", prop, "");
-  div.style.setProperty(prop, "64px 16px", "");
-  is(cs.getPropertyValue(prop), "28px",
+  div.style.setProperty(prop, "40px 20px", "");
+  is(cs.getPropertyValue(prop), "22px 23px",
      "radius-valued property " + prop + ": interpolation of radius with mixed units");
   check_distance(prop, "8% 12%", "-moz-calc(6% + 10px) -moz-calc(5px + 9%)",
                        "40px 20px");
@@ -914,11 +912,9 @@ function test_transform_transition(prop) {
       expected_uncomputed: 'translateY(-30%)',
       expected: 'matrix(1, 0, 0, 1, 0px, -15px)' },
     { start: 'none', end: 'rotate(90deg) translate(20%, 20%) rotate(-90deg)',
-      expected_uncomputed: 'rotate(22.5deg) translate(5%, 5%) rotate(-22.5deg)',
-      round_error_ok: true },
+      expected_uncomputed: 'rotate(22.5deg) translate(5%, 5%) rotate(-22.5deg)' },
     { start: 'none', end: 'rotate(-90deg) translate(20%, 20%) rotate(90deg)',
-      expected_uncomputed: 'rotate(-22.5deg) translate(5%, 5%) rotate(22.5deg)',
-      round_error_ok: true },
+      expected_uncomputed: 'rotate(-22.5deg) translate(5%, 5%) rotate(22.5deg)' },
     // test percent translation using matrix decomposition
     { start: 'rotate(45deg) rotate(-45deg)',
       end: 'rotate(90deg) translate(20%, 20%) rotate(-90deg)',
diff --git a/xpcom/io/Makefile.in b/xpcom/io/Makefile.in
index 2d2f9567ecf..37c7ed6de61 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 = -O3 -fno-strict-aliasing
+MODULE_OPTIMIZE_FLAGS = -Os -fno-strict-aliasing $(MOZ_OPTIMIZE_SIZE_TWEAK)
 endif
 endif