--- a/build/moz.configure/old.configure
+++ b/build/moz.configure/old.configure
@@ -204,17 +204,16 @@ def old_configure_options(*options):
     '--enable-memory-sanitizer',
     '--enable-mobile-optimize',
     '--enable-necko-wifi',
     '--enable-negotiateauth',
     '--enable-nfc',
     '--enable-nspr-build',
     '--enable-official-branding',
     '--enable-oom-breakpoint',
-    '--enable-optimize',
     '--enable-parental-controls',
     '--enable-pie',
     '--enable-posix-nspr-emulation',
     '--enable-pref-extensions',
     '--enable-pulseaudio',
     '--enable-raw',
     '--enable-readline',
     '--enable-reflow-perf',

--- a/build/moz.configure/toolchain.configure
+++ b/build/moz.configure/toolchain.configure
@@ -6,16 +6,45 @@
 
 # PGO
 # ==============================================================
 option(env='MOZ_PGO', help='Build with profile guided optimizations')
 
 set_config('MOZ_PGO', depends('MOZ_PGO')(lambda x: bool(x)))
 add_old_configure_assignment('MOZ_PGO', depends('MOZ_PGO')(lambda x: bool(x)))
 
+# Code optimization
+# ==============================================================
+
+js_option('--enable-optimize',
+          nargs='?',
+          default=True,
+          help='Enable optimizations via compiler flags')
+
+@depends('--enable-optimize')
+def moz_optimize(option):
+    flags = None
+
+    if len(option):
+        val = '2'
+        flags = option[0]
+    elif option:
+        val = '1'
+    else:
+        val = None
+
+    return namespace(
+        optimize=val,
+        flags=flags,
+    )
+
+set_config('MOZ_OPTIMIZE', moz_optimize.optimize)
+add_old_configure_assignment('MOZ_OPTIMIZE', moz_optimize.optimize)
+add_old_configure_assignment('MOZ_CONFIGURE_OPTIMIZE_FLAGS', moz_optimize.flags)
+
 # yasm detection
 # ==============================================================
 yasm = check_prog('YASM', ['yasm'], allow_missing=True)
 
 
 @depends_if(yasm)
 @checking('yasm version')
 def yasm_version(yasm):

--- a/js/src/old-configure.in
+++ b/js/src/old-configure.in
@@ -1433,28 +1433,21 @@ dnl = Debugging Options
 dnl =
 dnl ========================================================
 MOZ_ARG_HEADER(Debugging and Optimizations)
 
 dnl ========================================================
 dnl = Enable code optimization. ON by default.
 dnl ========================================================
 
-MOZ_ARG_ENABLE_STRING(optimize,
-[  --disable-optimize      Disable compiler optimization
-  --enable-optimize=[OPT] Specify compiler optimization flags [OPT=-O]],
-[ if test "$enableval" != "no"; then
-    MOZ_OPTIMIZE=1
-    if test -n "$enableval" -a "$enableval" != "yes"; then
-        MOZ_OPTIMIZE_FLAGS=`echo "$enableval" | sed -e 's|\\\ | |g'`
-        MOZ_OPTIMIZE=2
-    fi
-else
-    MOZ_OPTIMIZE=
-fi ], MOZ_OPTIMIZE=1)
+# Use value from moz.configure if one is defined. Else use our computed
+# value.
+if test -n "${MOZ_CONFIGURE_OPTIMIZE_FLAGS}"; then
+    MOZ_OPTIMIZE_FLAGS=${MOZ_CONFIGURE_OPTIMIZE_FLAGS}
+fi
 
 MOZ_SET_FRAMEPTR_FLAGS
 
 if test "$COMPILE_ENVIRONMENT"; then
 if test -n "$MOZ_OPTIMIZE"; then
     AC_MSG_CHECKING([for valid optimization flags])
     _SAVE_CFLAGS=$CFLAGS
     CFLAGS="$CFLAGS $MOZ_OPTIMIZE_FLAGS"
@@ -1465,17 +1458,16 @@ if test -n "$MOZ_OPTIMIZE"; then
     AC_MSG_RESULT([$_results])
     if test "$_results" = "no"; then
         AC_MSG_ERROR([These compiler flags are invalid: $MOZ_OPTIMIZE_FLAGS])
     fi
     CFLAGS=$_SAVE_CFLAGS
 fi
 fi # COMPILE_ENVIRONMENT
 
-AC_SUBST(MOZ_OPTIMIZE)
 AC_SUBST(MOZ_FRAMEPTR_FLAGS)
 AC_SUBST(MOZ_OPTIMIZE_FLAGS)
 AC_SUBST(MOZ_OPTIMIZE_LDFLAGS)
 AC_SUBST(MOZ_PGO_OPTIMIZE_FLAGS)
 
 dnl ========================================================
 dnl = Trace logging. Enabled by default in DEBUG builds.
 dnl ========================================================

--- a/old-configure.in
+++ b/old-configure.in
@@ -3709,28 +3709,21 @@ if test "$MOZ_GFX_OPTIMIZE_MOBILE"; then
     AC_DEFINE(MOZ_GFX_OPTIMIZE_MOBILE)
     AC_DEFINE(MOZ_IGNORE_PAINT_WILL_RESAMPLE)
 fi
 
 dnl ========================================================
 dnl = Enable code optimization. ON by default.
 dnl ========================================================
 
-MOZ_ARG_ENABLE_STRING(optimize,
-[  --disable-optimize      Disable compiler optimization
-  --enable-optimize=[OPT] Specify compiler optimization flags [OPT=-O]],
-[ if test "$enableval" != "no"; then
-    MOZ_OPTIMIZE=1
-    if test -n "$enableval" -a "$enableval" != "yes"; then
-        MOZ_OPTIMIZE_FLAGS=`echo "$enableval" | sed -e 's|\\\ | |g'`
-        MOZ_OPTIMIZE=2
-    fi
-else
-    MOZ_OPTIMIZE=
-fi ], MOZ_OPTIMIZE=1)
+# Use value from moz.configure if one is defined. Else use our computed
+# value.
+if test -n "${MOZ_CONFIGURE_OPTIMIZE_FLAGS}"; then
+    MOZ_OPTIMIZE_FLAGS=${MOZ_CONFIGURE_OPTIMIZE_FLAGS}
+fi
 
 MOZ_SET_FRAMEPTR_FLAGS
 
 if test "$COMPILE_ENVIRONMENT"; then
 if test -n "$MOZ_OPTIMIZE"; then
     AC_MSG_CHECKING([for valid C compiler optimization flags])
     _SAVE_CFLAGS=$CFLAGS
     CFLAGS="$CFLAGS $MOZ_OPTIMIZE_FLAGS"
@@ -3741,17 +3734,16 @@ if test -n "$MOZ_OPTIMIZE"; then
     AC_MSG_RESULT([$_results])
     if test "$_results" = "no"; then
         AC_MSG_ERROR([These compiler flags for C are invalid: $MOZ_OPTIMIZE_FLAGS])
     fi
     CFLAGS=$_SAVE_CFLAGS
 fi
 fi # COMPILE_ENVIRONMENT
 
-AC_SUBST(MOZ_OPTIMIZE)
 AC_SUBST(MOZ_FRAMEPTR_FLAGS)
 AC_SUBST(MOZ_OPTIMIZE_FLAGS)
 AC_SUBST(MOZ_OPTIMIZE_LDFLAGS)
 AC_SUBST(MOZ_PGO_OPTIMIZE_FLAGS)
 
 dnl ========================================================
 dnl = Disable treating compiler warnings as errors
 dnl ========================================================