--- a/js/src/jit-test/lib/jitopts.js
+++ b/js/src/jit-test/lib/jitopts.js
@@ -4,16 +4,22 @@
 // different set of JIT toggles are set, since TBPL runs each jit-test
 // multiple times with a variety of flags.
 function jitTogglesMatch(opts) {
   var currentOpts = getJitCompilerOptions();
   for (var k in opts) {
     if (k.indexOf(".enable") > 0 && opts[k] != currentOpts[k])
       return false;
   }
+
+  // ARM64 does not yet have an Ion code generator, so return false if
+  // ion.enable is requested.
+  if (getBuildConfiguration()['arm64-simulator'] && opts['ion.enable'])
+    return false;
+
   return true;
 }
 
 // Run fn under a particular set of JIT options.
 function withJitOptions(opts, fn) {
   var oldOpts = getJitCompilerOptions();
   for (var k in opts)
     setJitCompilerOption(k, opts[k]);