diff --git a/addon/-private/attr.ts b/addon/-private/attr.ts
index 94d424cb3f3..f2c90b50c46 100644
--- a/addon/-private/attr.ts
+++ b/addon/-private/attr.ts
@@ -111,7 +111,22 @@ interface AttrOptions {
   @param {Object} options a hash of options
   @return {Attribute}
 */
-export default function attr(type?: string | AttrOptions, options?: AttrOptions) {
+function isDecorator(args) {
+  let isDecorator = args.length > 3;
+  if (!isDecorator && args.length === 3) {
+    // decorators calls start with (instance, key, definition)
+    if (typeof args[0] === 'object' && typeof args[1] === 'string' && typeof args[2] === 'object') {
+      isDecorator = true;
+    }
+  }
+
+  return isDecorator;
+}
+export default function attr(...args) {
+  return isDecorator(args) ? _attr()(...args) : _attr(...args);
+}
+
+function _attr(type?: string | AttrOptions, options?: AttrOptions) {
   if (typeof type === 'object') {
     options = type;
     type = undefined;
diff --git a/addon/-private/system/relationships/belongs-to.js b/addon/-private/system/relationships/belongs-to.js
index 21de15f0062..a50ae9f0cf5 100644
--- a/addon/-private/system/relationships/belongs-to.js
+++ b/addon/-private/system/relationships/belongs-to.js
@@ -101,7 +101,22 @@ import { DEBUG } from '@glimmer/env';
   @param {Object} options (optional) a hash of options
   @return {Ember.computed} relationship
 */
-export default function belongsTo(modelName, options) {
+function isDecorator(args) {
+  let isDecorator = args.length > 3;
+  if (!isDecorator && args.length === 3) {
+    // decorators calls start with (instance, key, definition)
+    if (typeof args[0] === 'object' && typeof args[1] === 'string' && typeof args[2] === 'object') {
+      isDecorator = true;
+    }
+  }
+
+  return isDecorator;
+}
+export default function belongsTo(...args) {
+  return isDecorator(args) ? _belongsTo()(...args) : _belongsTo(...args);
+}
+
+function _belongsTo(modelName, options) {
   let opts, userEnteredModelName;
   if (typeof modelName === 'object') {
     opts = modelName;
diff --git a/addon/-private/system/relationships/has-many.js b/addon/-private/system/relationships/has-many.js
index a142d54f7d7..07f29109719 100644
--- a/addon/-private/system/relationships/has-many.js
+++ b/addon/-private/system/relationships/has-many.js
@@ -143,7 +143,22 @@ import { DEBUG } from '@glimmer/env';
   @param {Object} options (optional) a hash of options
   @return {Ember.computed} relationship
 */
-export default function hasMany(type, options) {
+function isDecorator(args) {
+  let isDecorator = args.length > 3;
+  if (!isDecorator && args.length === 3) {
+    // decorators calls start with (instance, key, definition)
+    if (typeof args[0] === 'object' && typeof args[1] === 'string' && typeof args[2] === 'object') {
+      isDecorator = true;
+    }
+  }
+
+  return isDecorator;
+}
+export default function hasMany(...args) {
+  return isDecorator(args) ? _hasMany()(...args) : _hasMany(...args);
+}
+
+function _hasMany(type, options) {
   if (typeof type === 'object') {
     options = type;
     type = undefined;
diff --git a/tests/integration/records/decorators-test.js b/tests/integration/records/decorators-test.js
new file mode 100644
index 00000000000..66ca691b965
--- /dev/null
+++ b/tests/integration/records/decorators-test.js
@@ -0,0 +1,155 @@
+import { module, test } from 'qunit';
+import { setupTest } from 'ember-qunit';
+import Store from 'ember-data/store';
+import Model from 'ember-data/model';
+import attr from 'ember-data/attr';
+import { belongsTo, hasMany } from 'ember-data/relationships';
+
+class Group extends Model {
+  @belongsTo person;
+}
+class Pet extends Model {
+  @belongsTo person;
+}
+class Car extends Model {
+  @belongsTo person;
+}
+class Table extends Model {
+  @belongsTo person;
+}
+class Person extends Model {
+  @attr attrWithoutParens;
+  @attr() attrWithParens;
+  @attr('string') attrWithType;
+  @attr({ defaultValue: `and if you don't keep your feet,` }) attrWithDefaultValue;
+  @attr('string', { defaultValue: `there's no knowing where you might be swept off to.` })
+  attrWithTypeAndDefaultValue;
+
+  // belongsTo no parens
+  @belongsTo group;
+  // belongsTo One Arg
+  @belongsTo('car') belongsToWithType;
+  @belongsTo({ inverse: null }) pet;
+  // belongsTo two Args
+  @belongsTo('person', { inverse: 'belongsToWithTypeAndInverse' })
+  belongsToWithTypeAndInverse;
+
+  // hasMany no parens
+  @hasMany tables;
+  // hasMany one Arg
+  @hasMany('pet')
+  hasManyWithType;
+  // hasMany two args
+  @hasMany('person', { inverse: 'friends' }) hasManyWithTypeAndInverse;
+}
+
+module('Decorators', function(hooks) {
+  let store;
+  setupTest(hooks);
+
+  hooks.beforeEach(function() {
+    let { owner } = this;
+    owner.register('service:store', Store);
+    owner.register('model:person', Person);
+    owner.register('model:group', Group);
+    owner.register('model:pet', Pet);
+    owner.register('model:car', Car);
+    owner.register('model:table', Table);
+    store = owner.lookup('service:store');
+  });
+
+  test('@attr', async function(assert) {
+    let person = store.push({
+      data: {
+        type: 'person',
+        id: '1',
+        attributes: {
+          attrWithoutParens: `It's a dangerous business,`,
+          attrWithParens: 'Frodo, going out your door.',
+          attrWithType: 'You step onto the road,',
+          attrWithDefaultValue: null,
+          attrWithTypeAndDefaultValue: null,
+        },
+      },
+    });
+
+    let quote = `${person.attrWithoutParens} ${person.attrWithParens} ${person.attrWithType} ${
+      person.attrWithDefaultValue
+    } ${person.attrWithTypeAndDefaultValue}`;
+
+    const fullQuote = `It's a dangerous business, Frodo, going out your door. You step onto the road, and if you don't keep your feet, there's no knowing where you might be swept off to.`;
+
+    assert.equal(quote, fullQuote, 'Attrs work as expected');
+  });
+
+  test('@belongsTo', async function(assert) {
+    const person = store.push({
+      data: {
+        type: 'person',
+        id: '1',
+        relationships: {
+          group: { data: { type: 'group', id: '1' } },
+          pet: { data: { type: 'pet', id: '1' } },
+          belongsToWithType: { data: { type: 'car', id: '1' } },
+          belongsToWithTypeAndInverse: { data: { type: 'person', id: '2' } },
+        },
+      },
+      included: [
+        {
+          type: 'group',
+          id: '1',
+          relationships: {
+            person: { data: { type: 'person', id: '1' } },
+          },
+        },
+        {
+          type: 'pet',
+          id: '1',
+          attributes: {},
+        },
+        {
+          type: 'car',
+          id: '1',
+          relationships: {
+            person: { data: { type: 'person', id: '1' } },
+          },
+        },
+        {
+          type: 'person',
+          id: '2',
+          relationships: {
+            belongsToWithTypeAndInverse: { data: { type: 'person', id: '1' } },
+          },
+        },
+      ],
+    });
+    const group = store.peekRecord('group', '1');
+    const car = store.peekRecord('car', '1');
+    const pet = store.peekRecord('pet', '1');
+    const person2 = store.peekRecord('person', '2');
+
+    const personGroup = await person.group;
+    const personPet = await person.pet;
+    const personCar = await person.belongsToWithType;
+    const personPerson = await person.belongsToWithTypeAndInverse;
+
+    assert.ok(
+      personGroup === group,
+      'We configured the relationship corectly without parens on the decorator'
+    );
+    assert.ok(
+      personCar === car,
+      'We configured the relationship correctly when the decorator is given the type'
+    );
+    assert.ok(
+      personPet === pet,
+      'We configured the relationship correctly when the decorator is given only the inverse'
+    );
+    assert.ok(
+      personPerson === person2,
+      'We configured the relationship correctly when the decorator is given a type and inverse'
+    );
+  });
+
+  // test('@hasMany', async function() {});
+});