diff --git a/js/src/jit-test/tests/arguments/iterator-set-and-redefine.js b/js/src/jit-test/tests/arguments/iterator-set-and-redefine.js
deleted file mode 100644
index bcf182790f6e..000000000000
--- a/js/src/jit-test/tests/arguments/iterator-set-and-redefine.js
+++ /dev/null
@@ -1,33 +0,0 @@
-function mapped() {
-    var Iterator = {};
-
-    // First overwrite the iterator.
-    arguments[Symbol.iterator] = Iterator;
-
-    // And then redefine a property attribute.
-    Object.defineProperty(arguments, Symbol.iterator, {
-        writable: false
-    });
-
-    // Make sure redefining an attribute doesn't reset the iterator value.
-    assertEq(arguments[Symbol.iterator], Iterator);
-}
-mapped();
-
-function unmapped() {
-  "use strict";
-
-  var Iterator = {};
-
-  // First overwrite the iterator.
-  arguments[Symbol.iterator] = Iterator;
-
-  // And then redefine a property attribute.
-  Object.defineProperty(arguments, Symbol.iterator, {
-      writable: false
-  });
-
-  // Make sure redefining an attribute doesn't reset the iterator value.
-  assertEq(arguments[Symbol.iterator], Iterator);
-}
-unmapped();
diff --git a/js/src/jit-test/tests/cacheir/arguments-iterator-mapped.js b/js/src/jit-test/tests/cacheir/arguments-iterator-mapped.js
deleted file mode 100644
index 0b6024d9af70..000000000000
--- a/js/src/jit-test/tests/cacheir/arguments-iterator-mapped.js
+++ /dev/null
@@ -1,171 +0,0 @@
-// Test iteration with a mapped arguments object.
-
-function simple() {
-  function f() {
-    var sum = 0;
-    for (var v of arguments) {
-      sum += v;
-    }
-    return sum;
-  }
-
-  for (var i = 0; i < 100; ++i) {
-    assertEq(f(1, 2, 3), 6);
-  }
-}
-simple();
-
-function spreadCall() {
-  function f() {
-    var sum = 0;
-    for (var v of arguments) {
-      sum += v;
-    }
-    return sum;
-  }
-
-  function g() {
-    return f(...arguments);
-  }
-
-  for (var i = 0; i < 100; ++i) {
-    assertEq(g(1, 2, 3), 6);
-  }
-}
-spreadCall();
-
-function spreadArray() {
-  function f() {
-    var arr = [...arguments];
-    var sum = 0;
-    for (var v of arr) {
-      sum += v;
-    }
-    return sum;
-  }
-
-  for (var i = 0; i < 100; ++i) {
-    assertEq(f(1, 2, 3), 6);
-  }
-}
-spreadArray();
-
-function reifyIterator() {
-  var reify = false;
-  function f() {
-    if (reify) {
-      // Redefining any property attributes will reify the iterator property.
-      Object.defineProperty(arguments, Symbol.iterator, {
-        writable: false
-      });
-    }
-
-    var sum = 0;
-    for (var v of arguments) {
-      sum += v;
-    }
-    return sum;
-  }
-
-  for (var i = 0; i <= 100; ++i) {
-    reify = i >= 50;
-    assertEq(f(1, 2, 3), 6);
-  }
-}
-reifyIterator();
-
-function overwriteIterator() {
-  var callCount = 0;
-  function Iterator() {
-    callCount += 1;
-    return Array.prototype[Symbol.iterator].call(this);
-  }
-
-  var overwrite = false;
-  function f() {
-    if (overwrite) {
-      arguments[Symbol.iterator] = Iterator;
-    }
-
-    var sum = 0;
-    for (var v of arguments) {
-      sum += v;
-    }
-    return sum;
-  }
-
-  for (var i = 0; i <= 100; ++i) {
-    overwrite = i > 50;
-    assertEq(f(1, 2, 3), 6);
-  }
-  assertEq(callCount, 50);
-}
-overwriteIterator();
-
-function deleteIterator() {
-  var remove = false;
-  function f() {
-    // Deleting Symbol.iterator won't change the shape of the arguments object.
-    // That's why we need to use a separate guard instruction to check if the
-    // iterator property was modified.
-    if (remove) {
-      delete arguments[Symbol.iterator];
-    }
-
-    var sum = 0;
-    for (var v of arguments) {
-      sum += v;
-    }
-    return sum;
-  }
-
-  var error;
-  try {
-    for (var i = 0; i <= 100; ++i) {
-      remove = i === 100;
-      assertEq(f(1, 2, 3), 6);
-    }
-  } catch (e) {
-    error = e;
-  }
-  assertEq(error instanceof TypeError, true);
-}
-deleteIterator();
-
-function deleteIteratorInherit() {
-  var callCount = 0;
-  function Iterator() {
-    callCount += 1;
-    return Array.prototype[Symbol.iterator].call(this);
-  }
-
-  Object.prototype[Symbol.iterator] = Iterator;
-
-  var remove = false;
-  function f() {
-    // Deleting Symbol.iterator won't change the shape of the arguments object.
-    // That's why we need to use a separate guard instruction to check if the
-    // iterator property was modified.
-    if (remove) {
-      delete arguments[Symbol.iterator];
-    }
-
-    var sum = 0;
-    for (var v of arguments) {
-      sum += v;
-    }
-    return sum;
-  }
-
-  for (var i = 0; i <= 100; ++i) {
-    remove = i === 100;
-    assertEq(f(1, 2, 3), 6);
-  }
-  assertEq(callCount, 1);
-
-  delete Object.prototype[Symbol.iterator];
-}
-deleteIteratorInherit();
-
-// Don't add tests below this point because |Object.prototype[Symbol.iterator]|
-// was modified, which may lead to engine-wide deoptimisations.
diff --git a/js/src/jit-test/tests/cacheir/arguments-iterator-unmapped.js b/js/src/jit-test/tests/cacheir/arguments-iterator-unmapped.js
deleted file mode 100644
index 29b2163596c8..000000000000
--- a/js/src/jit-test/tests/cacheir/arguments-iterator-unmapped.js
+++ /dev/null
@@ -1,184 +0,0 @@
-// Test iteration with an unmapped arguments object.
-
-function simple() {
-  function f() {
-    "use strict";
-
-    var sum = 0;
-    for (var v of arguments) {
-      sum += v;
-    }
-    return sum;
-  }
-
-  for (var i = 0; i < 100; ++i) {
-    assertEq(f(1, 2, 3), 6);
-  }
-}
-simple();
-
-function spreadCall() {
-  function f() {
-    var sum = 0;
-    for (var v of arguments) {
-      sum += v;
-    }
-    return sum;
-  }
-
-  function g() {
-    "use strict";
-    return f(...arguments);
-  }
-
-  for (var i = 0; i < 100; ++i) {
-    assertEq(g(1, 2, 3), 6);
-  }
-}
-spreadCall();
-
-function spreadArray() {
-  function f() {
-    "use strict";
-
-    var arr = [...arguments];
-    var sum = 0;
-    for (var v of arr) {
-      sum += v;
-    }
-    return sum;
-  }
-
-  for (var i = 0; i < 100; ++i) {
-    assertEq(f(1, 2, 3), 6);
-  }
-}
-spreadArray();
-
-function reifyIterator() {
-  var reify = false;
-  function f() {
-    "use strict";
-
-    if (reify) {
-      // Redefining any property attributes will reify the iterator property.
-      Object.defineProperty(arguments, Symbol.iterator, {
-        writable: false
-      });
-    }
-
-    var sum = 0;
-    for (var v of arguments) {
-      sum += v;
-    }
-    return sum;
-  }
-
-  for (var i = 0; i <= 100; ++i) {
-    reify = i >= 50;
-    assertEq(f(1, 2, 3), 6);
-  }
-}
-reifyIterator();
-
-function overwriteIterator() {
-  var callCount = 0;
-  function Iterator() {
-    callCount += 1;
-    return Array.prototype[Symbol.iterator].call(this);
-  }
-
-  var overwrite = false;
-  function f() {
-    "use strict";
-
-    if (overwrite) {
-      arguments[Symbol.iterator] = Iterator;
-    }
-
-    var sum = 0;
-    for (var v of arguments) {
-      sum += v;
-    }
-    return sum;
-  }
-
-  for (var i = 0; i <= 100; ++i) {
-    overwrite = i > 50;
-    assertEq(f(1, 2, 3), 6);
-  }
-  assertEq(callCount, 50);
-}
-overwriteIterator();
-
-function deleteIterator() {
-  var remove = false;
-  function f() {
-    "use strict";
-
-    // Deleting Symbol.iterator won't change the shape of the arguments object.
-    // That's why we need to use a separate guard instruction to check if the
-    // iterator property was modified.
-    if (remove) {
-      delete arguments[Symbol.iterator];
-    }
-
-    var sum = 0;
-    for (var v of arguments) {
-      sum += v;
-    }
-    return sum;
-  }
-
-  var error;
-  try {
-    for (var i = 0; i <= 100; ++i) {
-      remove = i === 100;
-      assertEq(f(1, 2, 3), 6);
-    }
-  } catch (e) {
-    error = e;
-  }
-  assertEq(error instanceof TypeError, true);
-}
-deleteIterator();
-
-function deleteIteratorInherit() {
-  var callCount = 0;
-  function Iterator() {
-    callCount += 1;
-    return Array.prototype[Symbol.iterator].call(this);
-  }
-
-  Object.prototype[Symbol.iterator] = Iterator;
-
-  var remove = false;
-  function f() {
-    "use strict";
-
-    // Deleting Symbol.iterator won't change the shape of the arguments object.
-    // That's why we need to use a separate guard instruction to check if the
-    // iterator property was modified.
-    if (remove) {
-      delete arguments[Symbol.iterator];
-    }
-
-    var sum = 0;
-    for (var v of arguments) {
-      sum += v;
-    }
-    return sum;
-  }
-
-  for (var i = 0; i <= 100; ++i) {
-    remove = i === 100;
-    assertEq(f(1, 2, 3), 6);
-  }
-  assertEq(callCount, 1);
-
-  delete Object.prototype[Symbol.iterator];
-}
-deleteIteratorInherit();
-
-// Don't add tests below this point because |Object.prototype[Symbol.iterator]|
-// was modified, which may lead to engine-wide deoptimisations.
diff --git a/js/src/jit/AliasAnalysis.cpp b/js/src/jit/AliasAnalysis.cpp
index 96736369a5a1..3ce282191bce 100644
--- a/js/src/jit/AliasAnalysis.cpp
+++ b/js/src/jit/AliasAnalysis.cpp
@@ -159,7 +159,6 @@ static inline const MDefinition* GetObject(const MDefinition* ins) {
     case MDefinition::Opcode::ArgumentsObjectLength:
     case MDefinition::Opcode::FunctionLength:
     case MDefinition::Opcode::FunctionName:
-    case MDefinition::Opcode::GuardArgumentsObjectNotOverriddenIterator:
       object = ins->getOperand(0);
       break;
     case MDefinition::Opcode::GetPropertyCache:
diff --git a/js/src/jit/BaselineCacheIRCompiler.cpp b/js/src/jit/BaselineCacheIRCompiler.cpp
index 71c638436618..fcd294a27fff 100644
--- a/js/src/jit/BaselineCacheIRCompiler.cpp
+++ b/js/src/jit/BaselineCacheIRCompiler.cpp
@@ -922,6 +922,7 @@ bool BaselineCacheIRCompiler::emitStoreSlotShared(bool isFixed,
                                                   ObjOperandId objId,
                                                   uint32_t offsetOffset,
                                                   ValOperandId rhsId) {
+  JitSpew(JitSpew_Codegen, "%s", __FUNCTION__);
   Address offsetAddr = stubAddress(offsetOffset);
 
   // Allocate the fixed registers first. These need to be fixed for
@@ -977,6 +978,7 @@ bool BaselineCacheIRCompiler::emitAddAndStoreSlotShared(
     CacheOp op, ObjOperandId objId, uint32_t offsetOffset, ValOperandId rhsId,
     bool changeGroup, uint32_t newGroupOffset, uint32_t newShapeOffset,
     Maybe<uint32_t> numNewSlotsOffset) {
+  JitSpew(JitSpew_Codegen, "%s", __FUNCTION__);
   Address offsetAddr = stubAddress(offsetOffset);
 
   // Allocate the fixed registers first. These need to be fixed for
diff --git a/js/src/jit/CacheIR.cpp b/js/src/jit/CacheIR.cpp
index 48e4c5897499..7bd95a3c069e 100644
--- a/js/src/jit/CacheIR.cpp
+++ b/js/src/jit/CacheIR.cpp
@@ -369,7 +369,6 @@ AttachDecision GetPropIRGenerator::tryAttachStub() {
       TRY_ATTACH(
           tryAttachXrayCrossCompartmentWrapper(obj, objId, id, receiverId));
       TRY_ATTACH(tryAttachFunction(obj, objId, id));
-      TRY_ATTACH(tryAttachArgumentsObjectIterator(obj, objId, id));
       TRY_ATTACH(tryAttachProxy(obj, objId, id, receiverId));
 
       trackAttached(IRGenerator::NotAttached);
@@ -2015,46 +2014,6 @@ AttachDecision GetPropIRGenerator::tryAttachFunction(HandleObject obj,
   return AttachDecision::Attach;
 }
 
-AttachDecision GetPropIRGenerator::tryAttachArgumentsObjectIterator(
-    HandleObject obj, ObjOperandId objId, HandleId id) {
-  if (!obj->is<ArgumentsObject>()) {
-    return AttachDecision::NoAction;
-  }
-
-  if (!JSID_IS_SYMBOL(id) ||
-      JSID_TO_SYMBOL(id) != cx_->wellKnownSymbols().iterator) {
-    return AttachDecision::NoAction;
-  }
-
-  auto* args = &obj->as<ArgumentsObject>();
-  if (args->hasOverriddenIterator()) {
-    return AttachDecision::NoAction;
-  }
-
-  RootedValue iterator(cx_);
-  if (!ArgumentsObject::getArgumentsIterator(cx_, &iterator)) {
-    cx_->recoverFromOutOfMemory();
-    return AttachDecision::NoAction;
-  }
-  MOZ_ASSERT(iterator.isObject());
-
-  maybeEmitIdGuard(id);
-  if (args->is<MappedArgumentsObject>()) {
-    writer.guardClass(objId, GuardClassKind::MappedArguments);
-  } else {
-    MOZ_ASSERT(args->is<UnmappedArgumentsObject>());
-    writer.guardClass(objId, GuardClassKind::UnmappedArguments);
-  }
-  writer.guardArgumentsObjectNotOverriddenIterator(objId);
-
-  ObjOperandId iterId = writer.loadObject(&iterator.toObject());
-  writer.loadObjectResult(iterId);
-  writer.typeMonitorResult();
-
-  trackAttached("ArgumentsObjectIterator");
-  return AttachDecision::Attach;
-}
-
 AttachDecision GetPropIRGenerator::tryAttachModuleNamespace(HandleObject obj,
                                                             ObjOperandId objId,
                                                             HandleId id) {
diff --git a/js/src/jit/CacheIR.h b/js/src/jit/CacheIR.h
index d3f6803aa055..b2e61d6aaa27 100644
--- a/js/src/jit/CacheIR.h
+++ b/js/src/jit/CacheIR.h
@@ -1299,9 +1299,6 @@ class MOZ_RAII GetPropIRGenerator : public IRGenerator {
                                                       ValOperandId receiverId);
   AttachDecision tryAttachFunction(HandleObject obj, ObjOperandId objId,
                                    HandleId id);
-  AttachDecision tryAttachArgumentsObjectIterator(HandleObject obj,
-                                                  ObjOperandId objId,
-                                                  HandleId id);
 
   AttachDecision tryAttachGenericProxy(HandleObject obj, ObjOperandId objId,
                                        HandleId id, bool handleDOMProxies);
diff --git a/js/src/jit/CacheIRCompiler.cpp b/js/src/jit/CacheIRCompiler.cpp
index 7543387de824..899318813703 100644
--- a/js/src/jit/CacheIRCompiler.cpp
+++ b/js/src/jit/CacheIRCompiler.cpp
@@ -29,7 +29,6 @@
 #include "js/friend/XrayJitInfo.h"  // js::jit::GetXrayJitInfo
 #include "js/ScalarType.h"          // js::Scalar::Type
 #include "proxy/Proxy.h"
-#include "vm/ArgumentsObject.h"
 #include "vm/ArrayBufferObject.h"
 #include "vm/ArrayBufferViewObject.h"
 #include "vm/BigIntType.h"
@@ -2881,7 +2880,6 @@ bool CacheIRCompiler::emitInt32NegationResult(Int32OperandId inputId) {
 }
 
 bool CacheIRCompiler::emitInt32IncResult(Int32OperandId inputId) {
-  JitSpew(JitSpew_Codegen, "%s", __FUNCTION__);
   AutoOutputRegister output(*this);
   Register input = allocator.useRegister(masm, inputId);
   AutoScratchRegisterMaybeOutput scratch(allocator, masm, output);
@@ -2899,7 +2897,6 @@ bool CacheIRCompiler::emitInt32IncResult(Int32OperandId inputId) {
 }
 
 bool CacheIRCompiler::emitInt32DecResult(Int32OperandId inputId) {
-  JitSpew(JitSpew_Codegen, "%s", __FUNCTION__);
   AutoOutputRegister output(*this);
   Register input = allocator.useRegister(masm, inputId);
   AutoScratchRegisterMaybeOutput scratch(allocator, masm, output);
@@ -2975,12 +2972,10 @@ bool CacheIRCompiler::emitDoubleIncDecResult(bool isInc,
 }
 
 bool CacheIRCompiler::emitDoubleIncResult(NumberOperandId inputId) {
-  JitSpew(JitSpew_Codegen, "%s", __FUNCTION__);
   return emitDoubleIncDecResult(true, inputId);
 }
 
 bool CacheIRCompiler::emitDoubleDecResult(NumberOperandId inputId) {
-  JitSpew(JitSpew_Codegen, "%s", __FUNCTION__);
   return emitDoubleIncDecResult(false, inputId);
 }
 
@@ -3570,7 +3565,6 @@ bool CacheIRCompiler::emitGuardObjectGroupNotPretenured(uint32_t groupOffset) {
 
 bool CacheIRCompiler::emitGuardFunctionHasJitEntry(ObjOperandId funId,
                                                    bool constructing) {
-  JitSpew(JitSpew_Codegen, "%s", __FUNCTION__);
   Register fun = allocator.useRegister(masm, funId);
 
   FailurePath* failure;
@@ -3640,7 +3634,6 @@ bool CacheIRCompiler::emitGuardFunctionIsConstructor(ObjOperandId funId) {
 }
 
 bool CacheIRCompiler::emitGuardNotClassConstructor(ObjOperandId funId) {
-  JitSpew(JitSpew_Codegen, "%s", __FUNCTION__);
   Register fun = allocator.useRegister(masm, funId);
   AutoScratchRegister scratch(allocator, masm);
 
@@ -3655,7 +3648,6 @@ bool CacheIRCompiler::emitGuardNotClassConstructor(ObjOperandId funId) {
 }
 
 bool CacheIRCompiler::emitGuardArrayIsPacked(ObjOperandId arrayId) {
-  JitSpew(JitSpew_Codegen, "%s", __FUNCTION__);
   Register array = allocator.useRegister(masm, arrayId);
   AutoScratchRegister scratch(allocator, masm);
   AutoScratchRegister scratch2(allocator, masm);
@@ -3669,22 +3661,6 @@ bool CacheIRCompiler::emitGuardArrayIsPacked(ObjOperandId arrayId) {
   return true;
 }
 
-bool CacheIRCompiler::emitGuardArgumentsObjectNotOverriddenIterator(
-    ObjOperandId objId) {
-  JitSpew(JitSpew_Codegen, "%s", __FUNCTION__);
-  Register obj = allocator.useRegister(masm, objId);
-  AutoScratchRegister scratch(allocator, masm);
-
-  FailurePath* failure;
-  if (!addFailurePath(&failure)) {
-    return false;
-  }
-
-  masm.branchArgumentsObjectHasOverridenIterator(obj, scratch,
-                                                 failure->label());
-  return true;
-}
-
 bool CacheIRCompiler::emitLoadDenseElementHoleResult(ObjOperandId objId,
                                                      Int32OperandId indexId) {
   JitSpew(JitSpew_Codegen, "%s", __FUNCTION__);
@@ -4710,6 +4686,7 @@ bool CacheIRCompiler::emitStoreTypedElement(ObjOperandId objId,
                                             Scalar::Type elementType,
                                             Int32OperandId indexId,
                                             uint32_t rhsId, bool handleOOB) {
+  JitSpew(JitSpew_Codegen, "%s", __FUNCTION__);
   Register obj = allocator.useRegister(masm, objId);
   Register index = allocator.useRegister(masm, indexId);
 
@@ -4806,7 +4783,6 @@ bool CacheIRCompiler::emitStoreTypedArrayElement(ObjOperandId objId,
                                                  Int32OperandId indexId,
                                                  uint32_t rhsId,
                                                  bool handleOOB) {
-  JitSpew(JitSpew_Codegen, "%s", __FUNCTION__);
   return emitStoreTypedElement(objId, TypedThingLayout::TypedArray, elementType,
                                indexId, rhsId, handleOOB);
 }
@@ -4816,7 +4792,6 @@ bool CacheIRCompiler::emitStoreTypedObjectElement(ObjOperandId objId,
                                                   Scalar::Type elementType,
                                                   Int32OperandId indexId,
                                                   uint32_t rhsId) {
-  JitSpew(JitSpew_Codegen, "%s", __FUNCTION__);
   return emitStoreTypedElement(objId, layout, elementType, indexId, rhsId,
                                false);
 }
@@ -4854,6 +4829,7 @@ static void EmitAllocateBigInt(MacroAssembler& masm, Register result,
 bool CacheIRCompiler::emitLoadTypedElementResult(
     ObjOperandId objId, Int32OperandId indexId, TypedThingLayout layout,
     Scalar::Type elementType, bool handleOOB, bool allowDoubleForUint32) {
+  JitSpew(JitSpew_Codegen, "%s", __FUNCTION__);
   AutoOutputRegister output(*this);
   Register obj = allocator.useRegister(masm, objId);
   Register index = allocator.useRegister(masm, indexId);
@@ -4981,7 +4957,6 @@ bool CacheIRCompiler::emitLoadTypedElementResult(
 bool CacheIRCompiler::emitLoadTypedArrayElementResult(
     ObjOperandId objId, Int32OperandId indexId, Scalar::Type elementType,
     bool handleOOB, bool allowDoubleForUint32) {
-  JitSpew(JitSpew_Codegen, "%s", __FUNCTION__);
   return emitLoadTypedElementResult(objId, indexId,
                                     TypedThingLayout::TypedArray, elementType,
                                     handleOOB, allowDoubleForUint32);
@@ -4990,7 +4965,6 @@ bool CacheIRCompiler::emitLoadTypedArrayElementResult(
 bool CacheIRCompiler::emitLoadTypedObjectElementResult(
     ObjOperandId objId, Int32OperandId indexId, TypedThingLayout layout,
     Scalar::Type elementType) {
-  JitSpew(JitSpew_Codegen, "%s", __FUNCTION__);
   return emitLoadTypedElementResult(objId, indexId, layout, elementType,
                                     /* handleOOB = */ false,
                                     /* allowDoubleForUint32 = */ true);
diff --git a/js/src/jit/CacheIROps.yaml b/js/src/jit/CacheIROps.yaml
index c5443626f193..a54fd821ffdb 100644
--- a/js/src/jit/CacheIROps.yaml
+++ b/js/src/jit/CacheIROps.yaml
@@ -663,13 +663,6 @@
   args:
     array: ObjId
 
-- name: GuardArgumentsObjectNotOverriddenIterator
-  shared: true
-  transpile: true
-  cost_estimate: 1
-  args:
-    obj: ObjId
-
 - name: LoadObject
   shared: true
   transpile: true
diff --git a/js/src/jit/CodeGenerator.cpp b/js/src/jit/CodeGenerator.cpp
index bcc5eab08322..696d006da756 100644
--- a/js/src/jit/CodeGenerator.cpp
+++ b/js/src/jit/CodeGenerator.cpp
@@ -8092,16 +8092,6 @@ void CodeGenerator::visitArgumentsObjectLength(LArgumentsObjectLength* lir) {
   bailoutFrom(&bail, lir->snapshot());
 }
 
-void CodeGenerator::visitGuardArgumentsObjectNotOverriddenIterator(
-    LGuardArgumentsObjectNotOverriddenIterator* lir) {
-  Register argsObj = ToRegister(lir->getArgsObject());
-  Register temp = ToRegister(lir->temp());
-
-  Label bail;
-  masm.branchArgumentsObjectHasOverridenIterator(argsObj, temp, &bail);
-  bailoutFrom(&bail, lir->snapshot());
-}
-
 void CodeGenerator::visitReturnFromCtor(LReturnFromCtor* lir) {
   ValueOperand value = ToValue(lir, LReturnFromCtor::ValueIndex);
   Register obj = ToRegister(lir->getObject());
diff --git a/js/src/jit/Lowering.cpp b/js/src/jit/Lowering.cpp
index a9078149fa2a..06a39fa9c183 100644
--- a/js/src/jit/Lowering.cpp
+++ b/js/src/jit/Lowering.cpp
@@ -345,18 +345,6 @@ void LIRGenerator::visitArgumentsObjectLength(MArgumentsObjectLength* ins) {
   define(lir, ins);
 }
 
-void LIRGenerator::visitGuardArgumentsObjectNotOverriddenIterator(
-    MGuardArgumentsObjectNotOverriddenIterator* ins) {
-  MDefinition* argsObj = ins->getArgsObject();
-  MOZ_ASSERT(argsObj->type() == MIRType::Object);
-
-  auto* lir = new (alloc())
-      LGuardArgumentsObjectNotOverriddenIterator(useRegister(argsObj), temp());
-  assignSnapshot(lir, BailoutKind::ArgumentsObjectAccess);
-  add(lir, ins);
-  redefine(ins, argsObj);
-}
-
 void LIRGenerator::visitReturnFromCtor(MReturnFromCtor* ins) {
   LReturnFromCtor* lir = new (alloc())
       LReturnFromCtor(useBox(ins->getValue()), useRegister(ins->getObject()));
diff --git a/js/src/jit/MIR.h b/js/src/jit/MIR.h
index e7f6fee9952e..224cae63684e 100644
--- a/js/src/jit/MIR.h
+++ b/js/src/jit/MIR.h
@@ -3787,36 +3787,6 @@ class MArgumentsObjectLength : public MUnaryInstruction,
   }
 };
 
-// Guard that the |ArgumentsObject::ITERATOR_OVERRIDDEN_BIT| flag isn't set.
-class MGuardArgumentsObjectNotOverriddenIterator
-    : public MUnaryInstruction,
-      public SingleObjectPolicy::Data {
-  explicit MGuardArgumentsObjectNotOverriddenIterator(MDefinition* argsObj)
-      : MUnaryInstruction(classOpcode, argsObj) {
-    setResultType(MIRType::Object);
-    setResultTypeSet(argsObj->resultTypeSet());
-    setMovable();
-    setGuard();
-  }
-
- public:
-  INSTRUCTION_HEADER(GuardArgumentsObjectNotOverriddenIterator)
-  TRIVIAL_NEW_WRAPPERS
-  NAMED_OPERANDS((0, getArgsObject))
-
-  bool congruentTo(const MDefinition* ins) const override {
-    return congruentIfOperandsEqual(ins);
-  }
-
-  AliasSet getAliasSet() const override {
-    // Even though the "iterator" property is lazily resolved, it acts similar
-    // to a normal property load, so we can treat this operation like any other
-    // property read.
-    return AliasSet::Load(AliasSet::ObjectFields | AliasSet::FixedSlot |
-                          AliasSet::DynamicSlot);
-  }
-};
-
 // Given a MIRType::Value A and a MIRType::Object B:
 // If the Value may be safely unboxed to an Object, return Object(A).
 // Otherwise, return B.
diff --git a/js/src/jit/MacroAssembler.cpp b/js/src/jit/MacroAssembler.cpp
index 7ee76ce80a32..4ff26e68f77b 100644
--- a/js/src/jit/MacroAssembler.cpp
+++ b/js/src/jit/MacroAssembler.cpp
@@ -4283,17 +4283,6 @@ void MacroAssembler::loadArgumentsObjectLength(Register obj, Register output,
   rshift32(Imm32(ArgumentsObject::PACKED_BITS_COUNT), output);
 }
 
-void MacroAssembler::branchArgumentsObjectHasOverridenIterator(Register obj,
-                                                               Register temp,
-                                                               Label* label) {
-  // Get initial length value.
-  unboxInt32(Address(obj, ArgumentsObject::getInitialLengthSlotOffset()), temp);
-
-  // Ensure no overridden iterator.
-  branchTest32(Assembler::NonZero, temp,
-               Imm32(ArgumentsObject::ITERATOR_OVERRIDDEN_BIT), label);
-}
-
 static constexpr bool ValidateShiftRange(Scalar::Type from, Scalar::Type to) {
   for (Scalar::Type type = from; type < to; type = Scalar::Type(type + 1)) {
     if (TypedArrayShift(type) != TypedArrayShift(from)) {
diff --git a/js/src/jit/MacroAssembler.h b/js/src/jit/MacroAssembler.h
index 73cd2629526f..4931c5e375a9 100644
--- a/js/src/jit/MacroAssembler.h
+++ b/js/src/jit/MacroAssembler.h
@@ -3644,9 +3644,6 @@ class MacroAssembler : public MacroAssemblerSpecific {
 
   void loadArgumentsObjectLength(Register obj, Register output, Label* fail);
 
-  void branchArgumentsObjectHasOverridenIterator(Register obj, Register temp,
-                                                 Label* label);
-
   void typedArrayElementShift(Register obj, Register output);
   void branchIfClassIsNotTypedArray(Register clasp, Label* notTypedArray);
 
diff --git a/js/src/jit/WarpCacheIRTranspiler.cpp b/js/src/jit/WarpCacheIRTranspiler.cpp
index 28a388726e73..fd4fa381314b 100644
--- a/js/src/jit/WarpCacheIRTranspiler.cpp
+++ b/js/src/jit/WarpCacheIRTranspiler.cpp
@@ -834,17 +834,6 @@ bool WarpCacheIRTranspiler::emitGuardArrayIsPacked(ObjOperandId arrayId) {
   return true;
 }
 
-bool WarpCacheIRTranspiler::emitGuardArgumentsObjectNotOverriddenIterator(
-    ObjOperandId objId) {
-  MDefinition* obj = getOperand(objId);
-
-  auto* ins = MGuardArgumentsObjectNotOverriddenIterator::New(alloc(), obj);
-  add(ins);
-
-  setOperand(objId, ins);
-  return true;
-}
-
 bool WarpCacheIRTranspiler::emitLoadFrameCalleeResult() {
   if (const CallInfo* callInfo = builder_->inlineCallInfo()) {
     pushResult(callInfo->callee());
diff --git a/js/src/jit/shared/LIR-shared.h b/js/src/jit/shared/LIR-shared.h
index 2d2fba41be5d..32aefd1171b9 100644
--- a/js/src/jit/shared/LIR-shared.h
+++ b/js/src/jit/shared/LIR-shared.h
@@ -927,23 +927,6 @@ class LArgumentsObjectLength : public LInstructionHelper<1, 1, 0> {
   const LAllocation* getArgsObject() { return getOperand(0); }
 };
 
-// Guard that the arguments object has no overridden iterator.
-class LGuardArgumentsObjectNotOverriddenIterator
-    : public LInstructionHelper<0, 1, 1> {
- public:
-  LIR_HEADER(GuardArgumentsObjectNotOverriddenIterator)
-
-  explicit LGuardArgumentsObjectNotOverriddenIterator(
-      const LAllocation& argsObj, const LDefinition& temp)
-      : LInstructionHelper(classOpcode) {
-    setOperand(0, argsObj);
-    setTemp(0, temp);
-  }
-
-  const LAllocation* getArgsObject() { return getOperand(0); }
-  const LDefinition* temp() { return this->getTemp(0); }
-};
-
 // If the Value is an Object, return unbox(Value).
 // Otherwise, return the other Object.
 class LReturnFromCtor : public LInstructionHelper<1, BOX_PIECES + 1, 0> {
diff --git a/js/src/vm/ArgumentsObject.cpp b/js/src/vm/ArgumentsObject.cpp
index 316e241096c1..72fc584a748a 100644
--- a/js/src/vm/ArgumentsObject.cpp
+++ b/js/src/vm/ArgumentsObject.cpp
@@ -538,13 +538,18 @@ static bool MappedArgSetter(JSContext* cx, HandleObject obj, HandleId id,
          NativeDefineDataProperty(cx, argsobj, id, v, attrs, result);
 }
 
-/* static */
-bool ArgumentsObject::getArgumentsIterator(JSContext* cx,
-                                           MutableHandleValue val) {
+static bool DefineArgumentsIterator(JSContext* cx,
+                                    Handle<ArgumentsObject*> argsobj) {
+  RootedId iteratorId(cx, SYMBOL_TO_JSID(cx->wellKnownSymbols().iterator));
   HandlePropertyName shName = cx->names().ArrayValues;
   RootedAtom name(cx, cx->names().values);
-  return GlobalObject::getSelfHostedFunction(cx, cx->global(), shName, name, 0,
-                                             val);
+  RootedValue val(cx);
+  if (!GlobalObject::getSelfHostedFunction(cx, cx->global(), shName, name, 0,
+                                           &val)) {
+    return false;
+  }
+  return NativeDefineDataProperty(cx, argsobj, iteratorId, val,
+                                  JSPROP_RESOLVING);
 }
 
 /* static */
@@ -570,12 +575,7 @@ bool ArgumentsObject::reifyIterator(JSContext* cx,
     return true;
   }
 
-  RootedId iteratorId(cx, SYMBOL_TO_JSID(cx->wellKnownSymbols().iterator));
-  RootedValue val(cx);
-  if (!ArgumentsObject::getArgumentsIterator(cx, &val)) {
-    return false;
-  }
-  if (!NativeDefineDataProperty(cx, obj, iteratorId, val, JSPROP_RESOLVING)) {
+  if (!DefineArgumentsIterator(cx, obj)) {
     return false;
   }
 
@@ -594,7 +594,7 @@ bool MappedArgumentsObject::obj_resolve(JSContext* cx, HandleObject obj,
       return true;
     }
 
-    if (!reifyIterator(cx, argsobj)) {
+    if (!DefineArgumentsIterator(cx, argsobj)) {
       return false;
     }
     *resolvedp = true;
@@ -817,7 +817,7 @@ bool UnmappedArgumentsObject::obj_resolve(JSContext* cx, HandleObject obj,
       return true;
     }
 
-    if (!reifyIterator(cx, argsobj)) {
+    if (!DefineArgumentsIterator(cx, argsobj)) {
       return false;
     }
     *resolvedp = true;
diff --git a/js/src/vm/ArgumentsObject.h b/js/src/vm/ArgumentsObject.h
index 2d9c726296a1..7e0172d05405 100644
--- a/js/src/vm/ArgumentsObject.h
+++ b/js/src/vm/ArgumentsObject.h
@@ -277,11 +277,6 @@ class ArgumentsObject : public NativeObject {
    */
   static bool reifyIterator(JSContext* cx, Handle<ArgumentsObject*> obj);
 
-  /*
-   * Return the arguments iterator function.
-   */
-  static bool getArgumentsIterator(JSContext* cx, MutableHandleValue val);
-
   /* True iff any element has been assigned or its attributes
    * changed. */
   bool hasOverriddenElement() const {