diff --git a/js/src/frontend/Parser.cpp b/js/src/frontend/Parser.cpp
index 487ddf78dbf..13077a4e06e 100644
--- a/js/src/frontend/Parser.cpp
+++ b/js/src/frontend/Parser.cpp
@@ -5848,13 +5848,6 @@ Parser<FullParseHandler>::generatorExpr(ParseNode *kid)
         genfn->pn_pos.begin = body->pn_pos.begin = kid->pn_pos.begin;
         genfn->pn_pos.end = body->pn_pos.end = tokenStream.currentToken().pos.end;
 
-        if (AtomDefnPtr p = genpc.lexdeps->lookup(context->names().arguments)) {
-            Definition *dn = p.value();
-            ParseNode *errorNode = dn->dn_uses ? dn->dn_uses : body;
-            report(ParseError, false, errorNode, JSMSG_BAD_GENEXP_BODY, js_arguments_str);
-            return null();
-        }
-
         RootedPropertyName funName(context);
         if (!leaveFunction(genfn, funName))
             return null();
diff --git a/js/src/jit-test/tests/arguments/genexpr-1.js b/js/src/jit-test/tests/arguments/genexpr-1.js
new file mode 100644
index 00000000000..edac127239e
--- /dev/null
+++ b/js/src/jit-test/tests/arguments/genexpr-1.js
@@ -0,0 +1,7 @@
+// No 'arguments' binding in genexprs at toplevel.
+
+load(libdir + "asserts.js");
+
+delete this.arguments;  // it is defined in the shell
+var iter = (arguments for (x of [1]));
+assertThrowsInstanceOf(() => iter.next(), ReferenceError);
diff --git a/js/src/jit-test/tests/arguments/genexpr-2.js b/js/src/jit-test/tests/arguments/genexpr-2.js
new file mode 100644
index 00000000000..7d99a7df124
--- /dev/null
+++ b/js/src/jit-test/tests/arguments/genexpr-2.js
@@ -0,0 +1,4 @@
+// 'arguments' is lexically scoped in genexprs at toplevel.
+
+var arguments = 8;
+assertEq((arguments for (x of [1])).next(), 8);
diff --git a/js/src/jit-test/tests/arguments/genexpr-3.js b/js/src/jit-test/tests/arguments/genexpr-3.js
new file mode 100644
index 00000000000..5441aeb5824
--- /dev/null
+++ b/js/src/jit-test/tests/arguments/genexpr-3.js
@@ -0,0 +1,6 @@
+// 'arguments' is lexically scoped in genexpr in toplevel let-block.
+
+{
+    let arguments = [];
+    assertEq((arguments for (p in {a: 1})).next(), arguments);
+}
diff --git a/js/src/jit-test/tests/arguments/genexpr-4.js b/js/src/jit-test/tests/arguments/genexpr-4.js
new file mode 100644
index 00000000000..95e34a099ff
--- /dev/null
+++ b/js/src/jit-test/tests/arguments/genexpr-4.js
@@ -0,0 +1,7 @@
+// 'arguments' is lexically scoped in genexpr in function.
+
+function f() {
+    assertEq((arguments for (x of [0])).next(),
+             (arguments for (y of [1])).next());
+}
+f();
diff --git a/js/src/jit-test/tests/arguments/genexpr-5.js b/js/src/jit-test/tests/arguments/genexpr-5.js
new file mode 100644
index 00000000000..7dc74091e58
--- /dev/null
+++ b/js/src/jit-test/tests/arguments/genexpr-5.js
@@ -0,0 +1,8 @@
+// 'arguments' binding can be closed over and outlives the function activation.
+
+function f() {
+    return (arguments for (x of [1]));
+}
+
+var args = f("ponies").next();
+assertEq(args[0], "ponies");
diff --git a/js/src/jit-test/tests/arguments/genexpr-6.js b/js/src/jit-test/tests/arguments/genexpr-6.js
new file mode 100644
index 00000000000..9470f3dcb71
--- /dev/null
+++ b/js/src/jit-test/tests/arguments/genexpr-6.js
@@ -0,0 +1,12 @@
+// 'arguments' works in nested genexprs.
+
+function f() {
+    return ((((((arguments for (u of [0]))
+                for (v of [1]))
+               for (w of [2]))
+              for (x of [3]))
+             for (y of [4]))
+            for (z of [5]));
+}
+var args = f("ponies").next().next().next().next().next().next();
+assertEq(args[0], "ponies");
diff --git a/js/src/jit-test/tests/basic/bug660538.js b/js/src/jit-test/tests/basic/bug660538.js
index ccbf489c3d7..ae854cd7589 100644
--- a/js/src/jit-test/tests/basic/bug660538.js
+++ b/js/src/jit-test/tests/basic/bug660538.js
@@ -1,5 +1,3 @@
-// |jit-test| error: SyntaxError;
-
 Error.prototype.__proto__.p = 5;
 f = Function("return( \"\" <arguments for(w in[]))");
 for (i in f()) {}
diff --git a/js/src/tests/js1_8/genexps/regress-634472.js b/js/src/tests/js1_8/genexps/regress-634472.js
index eecd34a8ad8..c7cc2330774 100644
--- a/js/src/tests/js1_8/genexps/regress-634472.js
+++ b/js/src/tests/js1_8/genexps/regress-634472.js
@@ -24,14 +24,10 @@ function error(str) {
 }
 
 const JSMSG_GENEXP_YIELD         = error("(function(){((yield) for (x in []))})").message;
-const JSMSG_GENEXP_ARGUMENTS     = error("(function(){(arguments for (x in []))})").message;
 const JSMSG_TOP_YIELD            = error("yield").message;
 const JSMSG_YIELD_PAREN          = error("(function(){yield, 1})").message;
 const JSMSG_GENERIC              = error("(for)").message;
-const JSMSG_GENEXP_PAREN         = error("print(1, x for (x in []))").message;
-const JSMSG_BAD_GENERATOR_SYNTAX = error("(1, arguments for (x in []))").message;
-
-const JSMSG_GENEXP_MIX = { simple: JSMSG_BAD_GENERATOR_SYNTAX, call: JSMSG_GENEXP_ARGUMENTS };
+const JSMSG_BAD_GENERATOR_SYNTAX = error("(1, x for (x in []))").message;
 
 const cases = [
   // yield expressions
@@ -53,11 +49,8 @@ const cases = [
   { expr: "((((yield 1))))", top: JSMSG_TOP_YIELD, fun: null, gen: JSMSG_GENEXP_YIELD, desc: "deeply nested yield w/ arg" },
 
   // arguments
-  { expr: "arguments",         top: null, fun: null, gen: JSMSG_GENEXP_ARGUMENTS, desc: "simple arguments" },
-  { expr: "1, arguments",      top: null, fun: null, gen: JSMSG_GENEXP_ARGUMENTS, desc: "arguments in list" },
-  { expr: "(arguments)",       top: null, fun: null, gen: JSMSG_GENEXP_ARGUMENTS, desc: "simple arguments, parenthesized" },
-  { expr: "(1, arguments)",    top: null, fun: null, gen: JSMSG_GENEXP_ARGUMENTS, desc: "arguments in list, parenthesized" },
-  { expr: "((((arguments))))", top: null, fun: null, gen: JSMSG_GENEXP_ARGUMENTS, desc: "deeply nested arguments" },
+  { expr: "arguments",    top: null, fun: null, gen: null, desc: "arguments in list" },
+  { expr: "1, arguments", top: null, fun: null, gen: null, desc: "arguments in list" },
 
   // yield in generator expressions
   { expr: "(yield for (x in []))",           top: JSMSG_TOP_YIELD, fun: JSMSG_GENERIC,      gen: JSMSG_GENERIC,      desc: "simple yield in genexp" },
@@ -65,7 +58,7 @@ const cases = [
   { expr: "(yield, 1 for (x in []))",        top: JSMSG_TOP_YIELD, fun: JSMSG_YIELD_PAREN,  gen: JSMSG_YIELD_PAREN,  desc: "simple yield in list in genexp" },
   { expr: "(yield 1, 2 for (x in []))",      top: JSMSG_TOP_YIELD, fun: JSMSG_YIELD_PAREN,  gen: JSMSG_YIELD_PAREN,  desc: "yield w/ arg in list in genexp" },
   { expr: "(1, yield for (x in []))",        top: JSMSG_TOP_YIELD, fun: JSMSG_GENERIC,      gen: JSMSG_GENERIC,      desc: "simple yield at end of list in genexp" },
-  { expr: "(1, yield 2 for (x in []))",      top: JSMSG_TOP_YIELD, fun: { simple: JSMSG_GENEXP_YIELD, call: JSMSG_GENEXP_PAREN },
+  { expr: "(1, yield 2 for (x in []))",      top: JSMSG_TOP_YIELD, fun: { simple: JSMSG_GENEXP_YIELD, call: JSMSG_BAD_GENERATOR_SYNTAX },
                                                                                             gen: JSMSG_GENEXP_YIELD, desc: "yield w/ arg at end of list in genexp" },
   { expr: "((yield) for (x in []))",         top: JSMSG_TOP_YIELD, fun: JSMSG_GENEXP_YIELD, gen: JSMSG_GENEXP_YIELD, desc: "simple yield, parenthesized in genexp" },
   { expr: "((yield 1) for (x in []))",       top: JSMSG_TOP_YIELD, fun: JSMSG_GENEXP_YIELD, gen: JSMSG_GENEXP_YIELD, desc: "yield w/ arg, parenthesized in genexp" },
@@ -85,16 +78,16 @@ const cases = [
   { expr: "((((1, yield 2)) for (x in [])) for (y in []))", top: JSMSG_TOP_YIELD, fun: JSMSG_GENEXP_YIELD, gen: JSMSG_GENEXP_YIELD, desc: "deeply nested yield in multiple genexps" },
 
   // arguments in generator expressions
-  { expr: "(arguments for (x in []))",         top: JSMSG_GENEXP_ARGUMENTS, fun: JSMSG_GENEXP_ARGUMENTS, gen: JSMSG_GENEXP_ARGUMENTS, desc: "simple arguments in genexp" },
-  { expr: "(1, arguments for (x in []))",      top: JSMSG_GENEXP_MIX,       fun: JSMSG_GENEXP_MIX,       gen: JSMSG_GENEXP_MIX,       desc: "arguments in list in genexp" },
-  { expr: "((arguments) for (x in []))",       top: JSMSG_GENEXP_ARGUMENTS, fun: JSMSG_GENEXP_ARGUMENTS, gen: JSMSG_GENEXP_ARGUMENTS, desc: "arguments, parenthesized in genexp" },
-  { expr: "(1, (arguments) for (x in []))",    top: JSMSG_GENEXP_MIX,       fun: JSMSG_GENEXP_MIX,       gen: JSMSG_GENEXP_MIX,       desc: "arguments, parenthesized in list in genexp" },
-  { expr: "((1, arguments) for (x in []))",    top: JSMSG_GENEXP_ARGUMENTS, fun: JSMSG_GENEXP_ARGUMENTS, gen: JSMSG_GENEXP_ARGUMENTS, desc: "arguments in list, parenthesized in genexp" },
-  { expr: "(1, (2, arguments) for (x in []))", top: JSMSG_GENEXP_MIX,       fun: JSMSG_GENEXP_MIX,       gen: JSMSG_GENEXP_MIX,       desc: "arguments in list, parenthesized in list in genexp" },
+  { expr: "(arguments for (x in []))",         top: null,                       fun: null,                       gen: null,                       desc: "simple arguments in genexp" },
+  { expr: "(1, arguments for (x in []))",      top: JSMSG_BAD_GENERATOR_SYNTAX, fun: JSMSG_BAD_GENERATOR_SYNTAX, gen: JSMSG_BAD_GENERATOR_SYNTAX, desc: "arguments in list in genexp" },
+  { expr: "((arguments) for (x in []))",       top: null,                       fun: null,                       gen: null,                       desc: "arguments, parenthesized in genexp" },
+  { expr: "(1, (arguments) for (x in []))",    top: JSMSG_BAD_GENERATOR_SYNTAX, fun: JSMSG_BAD_GENERATOR_SYNTAX, gen: JSMSG_BAD_GENERATOR_SYNTAX, desc: "arguments, parenthesized in list in genexp" },
+  { expr: "((1, arguments) for (x in []))",    top: null,                       fun: null,                       gen: null,                       desc: "arguments in list, parenthesized in genexp" },
+  { expr: "(1, (2, arguments) for (x in []))", top: JSMSG_BAD_GENERATOR_SYNTAX, fun: JSMSG_BAD_GENERATOR_SYNTAX, gen: JSMSG_BAD_GENERATOR_SYNTAX, desc: "arguments in list, parenthesized in list in genexp" },
 
   // deeply nested arguments in generator expressions
-  { expr: "((((1, arguments))) for (x in []))",               top: JSMSG_GENEXP_ARGUMENTS, fun: JSMSG_GENEXP_ARGUMENTS, gen: JSMSG_GENEXP_ARGUMENTS, desc: "deeply nested arguments in genexp" },
-  { expr: "((((1, arguments)) for (x in [])) for (y in []))", top: JSMSG_GENEXP_ARGUMENTS, fun: JSMSG_GENEXP_ARGUMENTS, gen: JSMSG_GENEXP_ARGUMENTS, desc: "deeply nested arguments in multiple genexps" },
+  { expr: "((((1, arguments))) for (x in []))",               top: null, fun: null, gen: null, desc: "deeply nested arguments in genexp" },
+  { expr: "((((1, arguments)) for (x in [])) for (y in []))", top: null, fun: null, gen: null, desc: "deeply nested arguments in multiple genexps" },
 
   // legal yield/arguments in nested function
   { expr: "((function() { yield }) for (x in []))",           top: null, fun: null, gen: null, desc: "legal yield in nested function" },