diff --git a/src/Illuminate/Http/Request.php b/src/Illuminate/Http/Request.php
index 934488bd2a40..06bc955633fb 100644
--- a/src/Illuminate/Http/Request.php
+++ b/src/Illuminate/Http/Request.php
@@ -331,6 +331,19 @@ public function merge(array $input)
         return $this;
     }
 
+    /**
+     * Merge new input into the request's input, but only when that key is missing from the request.
+     *
+     * @param  array  $input
+     * @return $this
+     */
+    public function mergeIfMissing(array $input)
+    {
+        return $this->merge(collect($input)->filter(function ($value, $key) {
+            return $this->missing($key);
+        })->toArray());
+    }
+
     /**
      * Replace the input for the current request.
      *
diff --git a/tests/Http/HttpRequestTest.php b/tests/Http/HttpRequestTest.php
index 3a82b0a2cdf9..f625aa9e4723 100644
--- a/tests/Http/HttpRequestTest.php
+++ b/tests/Http/HttpRequestTest.php
@@ -752,6 +752,21 @@ public function testMergeMethod()
         $this->assertSame('Dayle', $request->input('buddy'));
     }
 
+    public function testMergeIfMissingMethod()
+    {
+        $request = Request::create('/', 'GET', ['name' => 'Taylor']);
+        $merge = ['boolean_setting' => 0];
+        $request->mergeIfMissing($merge);
+        $this->assertSame('Taylor', $request->input('name'));
+        $this->assertSame(0, $request->input('boolean_setting'));
+
+        $request = Request::create('/', 'GET', ['name' => 'Taylor', 'boolean_setting' => 1]);
+        $merge = ['boolean_setting' => 0];
+        $request->mergeIfMissing($merge);
+        $this->assertSame('Taylor', $request->input('name'));
+        $this->assertSame(1, $request->input('boolean_setting'));
+    }
+
     public function testReplaceMethod()
     {
         $request = Request::create('/', 'GET', ['name' => 'Taylor']);