diff --git a/lib/Common/ConfigFlagsList.h b/lib/Common/ConfigFlagsList.h
index f7277ace2e6..7e572f5c25c 100644
--- a/lib/Common/ConfigFlagsList.h
+++ b/lib/Common/ConfigFlagsList.h
@@ -570,7 +570,12 @@ PHASE(All)
 #define DEFAULT_CONFIG_ES7TrailingComma        (true)
 #define DEFAULT_CONFIG_ES7ValuesEntries        (true)
 #define DEFAULT_CONFIG_ESObjectGetOwnPropertyDescriptors (true)
+
+#ifdef COMPILE_DISABLE_ESSharedArrayBuffer
+#define DEFAULT_CONFIG_ESSharedArrayBuffer     (false)
+#else
 #define DEFAULT_CONFIG_ESSharedArrayBuffer     (false)
+#endif
 #define DEFAULT_CONFIG_ES6Verbose              (false)
 #define DEFAULT_CONFIG_ES6All                  (false)
 // ES6 DEFAULT BEHAVIOR
@@ -785,7 +790,7 @@ PHASE(All)
 // Release flags with parent and acronym
 #ifndef FLAGPRA
 #define FLAGPRA(Type, ParentName, Name, Acronym, String, Default) \
-        FLAGPR(Type, ParentName, Name, String, Default) \
+        FLAG_REGOVR_EXP(Type, Name, String, Default, ParentName, FALSE) \
         FLAGNR(Type, Acronym, String, Default)
 #endif
 
@@ -1017,6 +1022,10 @@ FLAGPR           (Boolean, ES6, ES6Verbose             , "Enable ES6 verbose tra
 FLAGPR_REGOVR_EXP(Boolean, ES6, ArrayBufferTransfer    , "Enable ArrayBuffer.transfer"                              , DEFAULT_CONFIG_ArrayBufferTransfer)
 
 FLAGPR           (Boolean, ES6, ESObjectGetOwnPropertyDescriptors, "Enable Object.getOwnPropertyDescriptors"        , DEFAULT_CONFIG_ESObjectGetOwnPropertyDescriptors)
+
+#ifndef COMPILE_DISABLE_ESSharedArrayBuffer
+    #define COMPILE_DISABLE_ESSharedArrayBuffer 0
+#endif
 FLAGPRA          (Boolean, ES6, ESSharedArrayBuffer    , sab     , "Enable SharedArrayBuffer"                       , DEFAULT_CONFIG_ESSharedArrayBuffer)
 
 // /ES6 (BLUE+1) features/flags