diff --git a/js/src/Makefile.in b/js/src/Makefile.in
index aea3b4ff160..62b8ab0ca04 100644
--- a/js/src/Makefile.in
+++ b/js/src/Makefile.in
@@ -88,7 +88,6 @@ MODULE_OPTIMIZE_FLAGS = -O2 -ip
 endif
 else # not INTEL_CXX
 
-#FAIL_ON_WARNINGS = 1
 MODULE_OPTIMIZE_FLAGS = -O3 -fstrict-aliasing -fno-stack-protector
 
 # We normally want -fomit-frame-pointer, but we want an explicit
diff --git a/js/src/config/autoconf.mk.in b/js/src/config/autoconf.mk.in
index b6310310a6d..03c77d7fed6 100644
--- a/js/src/config/autoconf.mk.in
+++ b/js/src/config/autoconf.mk.in
@@ -142,6 +142,7 @@ OS_LIBS		= @LIBS@
 ACDEFINES	= @MOZ_DEFINES@
 
 WARNINGS_AS_ERRORS = @WARNINGS_AS_ERRORS@
+FAIL_ON_WARNINGS = @FAIL_ON_WARNINGS@
 
 MOZ_OPTIMIZE	= @MOZ_OPTIMIZE@
 MOZ_OPTIMIZE_FLAGS = @MOZ_OPTIMIZE_FLAGS@
diff --git a/js/src/configure.in b/js/src/configure.in
index d0b723d2793..bbf9d97c373 100644
--- a/js/src/configure.in
+++ b/js/src/configure.in
@@ -4779,6 +4779,17 @@ if test "$MOZ_DISABLE_WARNINGS_AS_ERRORS"; then
    WARNINGS_AS_ERRORS=''
 fi
 
+dnl ========================================================
+dnl = Enable treating compile warnings as errors
+dnl ========================================================
+MOZ_ARG_ENABLE_BOOL(sm-fail-on-warnings,
+[  --enable-sm-fail-on-warnings
+                          Enable warnings as errors],
+    FAIL_ON_WARNINGS=1,
+    FAIL_ON_WARNINGS= )
+
+AC_SUBST(FAIL_ON_WARNINGS)
+
 dnl = Enable trace malloc
 dnl ========================================================
 NS_TRACE_MALLOC=${MOZ_TRACE_MALLOC}
diff --git a/js/src/shell/Makefile.in b/js/src/shell/Makefile.in
index 076abd65cb6..058b3b20a99 100644
--- a/js/src/shell/Makefile.in
+++ b/js/src/shell/Makefile.in
@@ -56,8 +56,6 @@ LIBS      = $(NSPR_LIBS) $(EDITLINE_LIBS) $(DEPTH)/$(LIB_PREFIX)js_static.$(LIB_
 
 LOCAL_INCLUDES += -I$(topsrcdir) -I..
 
-#FAIL_ON_WARNINGS = 1
-
 ifdef _MSC_VER
 ifdef WINCE
 WIN32_EXE_LDFLAGS += -ENTRY:mainACRTStartup