diff --git a/packages/ember-glimmer/lib/environment.js b/packages/ember-glimmer/lib/environment.js
index 1bfa3ed6bcb..3fa3e680911 100644
--- a/packages/ember-glimmer/lib/environment.js
+++ b/packages/ember-glimmer/lib/environment.js
@@ -6,11 +6,15 @@ import createIterable from './utils/iterable';
 import { RootReference, ConditionalReference } from './utils/references';
 
 import { default as concat } from './helpers/concat';
-import { default as inlineIf } from './helpers/inline-if';
+import {
+  inlineIf,
+  inlineUnless
+} from './helpers/inline-if-unless';
 
 const helpers = {
   concat,
-  if: inlineIf
+  if: inlineIf,
+  unless: inlineUnless
 };
 
 const VIEW_KEYWORD = 'view'; // legacy ? 'view' : symbol('view');
diff --git a/packages/ember-glimmer/lib/helpers/inline-if-unless.js b/packages/ember-glimmer/lib/helpers/inline-if-unless.js
new file mode 100644
index 00000000000..df1873ab967
--- /dev/null
+++ b/packages/ember-glimmer/lib/helpers/inline-if-unless.js
@@ -0,0 +1,68 @@
+/**
+@module ember
+@submodule ember-templates
+*/
+
+import { toBool as emberToBool } from './if-unless';
+import { assert } from 'ember-metal/debug';
+
+/**
+  The inline `if` helper conditionally renders a single property or string.
+  This helper acts like a ternary operator. If the first property is truthy,
+  the second argument will be displayed, otherwise, the third argument will be
+  displayed
+  ```handlebars
+  {{if useLongGreeting "Hello" "Hi"}} Alex
+  ```
+  You can use the `if` helper inside another helper as a subexpression.
+  ```handlebars
+  {{some-component height=(if isBig "100" "10")}}
+  ```
+  @method if
+  @for Ember.Templates.helpers
+  @public
+*/
+export function inlineIf(args) {
+  return resolveValue(args, true);
+}
+
+/**
+  The inline `unless` helper conditionally renders a single property or string.
+  This helper acts like a ternary operator. If the first property is falsy,
+  the second argument will be displayed, otherwise, the third argument will be
+  displayed
+  ```handlebars
+  {{unless useLongGreeting "Hi" "Hello"}} Ben
+  ```
+  You can use the `unless` helper inside another helper as a subexpression.
+  ```handlebars
+  {{some-component height=(unless isBig "10" "100")}}
+  ```
+  @method unless
+  @for Ember.Templates.helpers
+  @public
+*/
+export function inlineUnless(args) {
+  return resolveValue(args, false);
+}
+
+function resolveValue(args, truthy) {
+  assert(
+    'The inline form of the `if` and `unless` helpers expect two or ' +
+    'three arguments, e.g. `{{if trialExpired \'Expired\' expiryDate}}` ',
+    args.length === 2 || args.length === 3
+  );
+
+  let predicate = emberToBool(args[0]);
+  if (!truthy) {
+    predicate = !predicate;
+  }
+
+  if (predicate) {
+    return args[1];
+  } else {
+    //TODO: always return `args[2]` post glimmer2: https://github.com/emberjs/ember.js/pull/12920#discussion_r53213383
+    let falsyArgument = args[2];
+    return falsyArgument === undefined ? '' : falsyArgument;
+  }
+}
diff --git a/packages/ember-glimmer/lib/helpers/inline-if.js b/packages/ember-glimmer/lib/helpers/inline-if.js
deleted file mode 100644
index 7040af19c46..00000000000
--- a/packages/ember-glimmer/lib/helpers/inline-if.js
+++ /dev/null
@@ -1,39 +0,0 @@
-/**
-@module ember
-@submodule ember-templates
-*/
-
-import { toBool as emberToBool } from './if-unless';
-import { assert } from 'ember-metal/debug';
-
-/**
-  The inline `if` helper conditionally renders a single property or string.
-  This helper acts like a ternary operator. If the first property is truthy,
-  the second argument will be displayed, if not, the third argument will be
-  displayed
-  ```handlebars
-  {{if useLongGreeting "Hello" "Hi"}} Alex
-  ```
-  You can use the `if` helper inside another helper as a subexpression.
-  ```handlebars
-  {{some-component height=(if isBig "100" "10")}}
-  ```
-  @method if
-  @for Ember.Templates.helpers
-  @public
-*/
-export default function inlineIf(args) {
-  assert(
-   'The inline form of the `if` and `unless` helpers expect two or ' +
-   'three arguments, e.g. `{{if trialExpired \'Expired\' expiryDate}}` ',
-   args.length === 2 || args.length === 3
- );
-
-  if (emberToBool(args[0])) {
-    return args[1];
-  } else {
-    //TODO: always return `args[2]` post glimmer2: https://github.com/emberjs/ember.js/pull/12920#discussion_r53213383
-    let falsyArgument = args[2];
-    return falsyArgument === undefined ? '' : falsyArgument;
-  }
-}
diff --git a/packages/ember-glimmer/tests/integration/helpers/if-unless-test.js b/packages/ember-glimmer/tests/integration/helpers/if-unless-test.js
index e6851f7844f..7901b77b906 100644
--- a/packages/ember-glimmer/tests/integration/helpers/if-unless-test.js
+++ b/packages/ember-glimmer/tests/integration/helpers/if-unless-test.js
@@ -1,6 +1,4 @@
 import { moduleFor } from '../../utils/test-case';
-import { set } from 'ember-metal/property_set';
-
 import { TogglingHelperConditionalsTest } from '../../utils/shared-conditional-tests';
 
 moduleFor('Helpers test: inline {{if}}', class extends TogglingHelperConditionalsTest {
@@ -9,84 +7,128 @@ moduleFor('Helpers test: inline {{if}}', class extends TogglingHelperConditional
     return `{{if ${cond} ${truthy} ${falsy}}}`;
   }
 
-  ['@test it can omit the falsy argument']() {
-    this.render(`{{if cond1 'T1'}}{{if cond2 'T2'}}`, { cond1: true, cond2: false });
+  ['@test it raises when there are more than three arguments']() {
+    expectAssertion(() => {
+      this.render(`{{if condition 'a' 'b' 'c'}}`, { condition: true });
+    }, /The inline form of the `if` and `unless` helpers expect two or three arguments/);
+  }
+
+  ['@test it raises when there are less than two arguments']() {
+    expectAssertion(() => {
+      this.render(`{{if condition}}`, { condition: true });
+    }, /The inline form of the `if` and `unless` helpers expect two or three arguments/);
+  }
+
+});
+
+moduleFor('@glimmer Helpers test: nested {{if}} helpers (returning truthy values)', class extends TogglingHelperConditionalsTest {
+
+  templateFor({ cond, truthy, falsy }) {
+    return `{{if (if ${cond} ${cond} false) ${truthy} ${falsy}}}`;
+  }
+
+});
+
+moduleFor('@glimmer Helpers test: nested {{if}} helpers (returning falsy values)', class extends TogglingHelperConditionalsTest {
+
+  templateFor({ cond, truthy, falsy }) {
+    return `{{if (if ${cond} true ${cond}) ${truthy} ${falsy}}}`;
+  }
+
+});
+
+moduleFor('@glimmer Helpers test: {{if}} used with another helper', class extends TogglingHelperConditionalsTest {
+
+  wrapperFor(templates) {
+    return `{{concat ${templates.join(' ')}}}`;
+  }
+
+  templateFor({ cond, truthy, falsy }) {
+    return `(if ${cond} ${truthy} ${falsy})`;
+  }
 
-    this.assertText('T1');
+});
 
-    this.runTask(() => this.rerender());
+moduleFor('@glimmer Helpers test: {{if}} used in attribute position', class extends TogglingHelperConditionalsTest {
 
-    this.assertText('T1');
+  wrapperFor(templates) {
+    return `<div data-foo="${templates.join('')}" />`;
+  }
+
+  templateFor({ cond, truthy, falsy }) {
+    return `{{if ${cond} ${truthy} ${falsy}}}`;
+  }
+
+  textValue() {
+    return this.$('div').attr('data-foo');
+  }
 
-    this.runTask(() => set(this.context, 'cond1', false));
+});
 
-    this.assertText('');
+moduleFor('Helpers test: inline {{if}} and {{unless}} without the inverse argument', class extends TogglingHelperConditionalsTest {
 
-    this.runTask(() => {
-      set(this.context, 'cond1', true);
-      set(this.context, 'cond2', true);
-    });
+  templateFor({ cond, truthy, falsy }) {
+    return `{{if ${cond} ${truthy}}}{{unless ${cond} ${falsy}}}`;
+  }
 
-    this.assertText('T1T2');
+});
 
-    this.runTask(() => {
-      set(this.context, 'cond1', true);
-      set(this.context, 'cond2', false);
-    });
+moduleFor('Helpers test: inline {{unless}}', class extends TogglingHelperConditionalsTest {
 
-    this.assertText('T1');
+  templateFor({ cond, truthy, falsy }) {
+    return `{{unless ${cond} ${falsy} ${truthy}}}`;
   }
 
   ['@test it raises when there are more than three arguments']() {
     expectAssertion(() => {
-      this.render(`{{if condition 'a' 'b' 'c'}}`, { condition: true });
+      this.render(`{{unless condition 'a' 'b' 'c'}}`, { condition: true });
     }, /The inline form of the `if` and `unless` helpers expect two or three arguments/);
   }
 
   ['@test it raises when there are less than two arguments']() {
     expectAssertion(() => {
-      this.render(`{{if condition}}`, { condition: true });
+      this.render(`{{unless condition}}`, { condition: true });
     }, /The inline form of the `if` and `unless` helpers expect two or three arguments/);
   }
 
 });
 
-moduleFor('@glimmer Helpers test: nested {{if}} helpers (returning truthy values)', class extends TogglingHelperConditionalsTest {
+moduleFor('@glimmer Helpers test: nested {{unless}} helpers (returning truthy values)', class extends TogglingHelperConditionalsTest {
 
   templateFor({ cond, truthy, falsy }) {
-    return `{{if (if ${cond} ${cond} false) ${truthy} ${falsy}}}`;
+    return `{{unless (unless ${cond} false ${cond}) ${falsy} ${truthy}}}`;
   }
 
 });
 
-moduleFor('@glimmer Helpers test: nested {{if}} helpers (returning falsy values)', class extends TogglingHelperConditionalsTest {
+moduleFor('@glimmer Helpers test: nested {{unless}} helpers (returning falsy values)', class extends TogglingHelperConditionalsTest {
 
   templateFor({ cond, truthy, falsy }) {
-    return `{{if (if ${cond} true ${cond}) ${truthy} ${falsy}}}`;
+    return `{{unless (unless ${cond} ${cond} true) ${falsy} ${truthy}}}`;
   }
 
 });
 
-moduleFor('@glimmer Helpers test: {{if}} used with another helper', class extends TogglingHelperConditionalsTest {
+moduleFor('@glimmer Helpers test: {{unless}} used with another helper', class extends TogglingHelperConditionalsTest {
 
   wrapperFor(templates) {
     return `{{concat ${templates.join(' ')}}}`;
   }
 
   templateFor({ cond, truthy, falsy }) {
-    return `(if ${cond} ${truthy} ${falsy})`;
+    return `(unless ${cond} ${falsy} ${truthy})`;
   }
 
 });
 
-moduleFor('@glimmer Helpers test: {{if}} used in attribute position', class extends TogglingHelperConditionalsTest {
+moduleFor('@glimmer Helpers test: {{unless}} used in attribute position', class extends TogglingHelperConditionalsTest {
 
   wrapperFor(templates) {
     return `<div data-foo="${templates.join('')}" />`;
   }
 
   templateFor({ cond, truthy, falsy }) {
-    return `{{if ${cond} ${truthy} ${falsy}}}`;
+    return `{{unless ${cond} ${falsy} ${truthy}}}`;
   }
 
   textValue() {