diff --git a/src/Observable.php b/src/Observable.php
index 79db73ba..f06109bc 100644
--- a/src/Observable.php
+++ b/src/Observable.php
@@ -293,6 +293,33 @@ public function mergeAll(): Observable
         });
     }
 
+    /**
+     * Combine an Observable together with another Observable by merging their emissions into a single Observable.
+     * This variant of merge will hold errors emitted from component observables until all observables have
+     * either completed or errored.
+     *
+     * @return Observable
+     *
+     * @operator
+     * @reactivex mergeDelayError
+     */
+    public function mergeDelayError(Observable $o) : Observable {
+        return Observable::fromArray([$this, $o])
+            ->reduce(function ($a, Observable $o) {
+                $s = new Subject();
+                return [
+                    $a[0]->merge($o->catch(function (\Throwable $e) use ($s) {
+                        $s->onError($e);
+                        return Observable::empty();
+                    })),
+                    $a[1]->merge($s)
+                ];
+            }, [Observable::empty(), Observable::empty()])
+            ->flatMap(function ($a) {
+                return $a[0]->concat($a[1]);
+            });
+    }
+
     /**
      * Converts an array to an observable sequence
      *
diff --git a/test/Rx/Functional/Operator/MergeDelayErrorTest.php b/test/Rx/Functional/Operator/MergeDelayErrorTest.php
new file mode 100644
index 00000000..48ebdfe7
--- /dev/null
+++ b/test/Rx/Functional/Operator/MergeDelayErrorTest.php
@@ -0,0 +1,129 @@
+<?php
+
+declare(strict_types = 1);
+
+namespace Rx\Functional\Operator;
+
+use Rx\Functional\FunctionalTestCase;
+
+class MergeDelayErrorTest extends FunctionalTestCase
+{
+    /**
+     * @test
+     */
+    public function it_waits_for_complete_before_emitting_error()
+    {
+        $xs = $this->createColdObservable(array(
+                                              onNext(100, 4),
+                                              onNext(200, 2),
+                                              onNext(300, 3),
+                                              onNext(400, 1),
+                                              onCompleted(500)
+                                          ));
+
+        $ys = $this->createColdObservable(array(
+                                              onNext(50, 'foo'),
+                                              onNext(100, 'bar'),
+                                              onNext(150, 'baz'),
+                                              onError(160, new \Exception()),
+                                              onNext(200, 'qux'),
+                                              onCompleted(250)
+                                          ));
+
+        $results = $this->scheduler->startWithCreate(function() use ($xs, $ys) {
+            return $xs->mergeDelayError($ys);
+        });
+
+        $this->assertMessages(array(
+                                  onNext(250, 'foo'),
+                                  onNext(300, 4),
+                                  onNext(300, 'bar'),
+                                  onNext(350, 'baz'),
+                                  onNext(400, 2),
+                                  onNext(500, 3),
+                                  onNext(600, 1),
+                                  onError(700, new \Exception())
+                              ), $results->getMessages());
+
+        $this->assertSubscriptions(array(subscribe(200, 700)), $xs->getSubscriptions());
+        $this->assertSubscriptions(array(subscribe(200, 360)), $ys->getSubscriptions());
+    }
+
+    /**
+     * @test
+     */
+    public function it_waits_for_complete_before_emitting_error_2()
+    {
+        $xs = $this->createColdObservable(array(
+                                              onNext(100, 4),
+                                              onError(160, new \Exception()),
+                                              onNext(200, 2),
+                                              onNext(300, 3),
+                                              onNext(400, 1),
+                                              onCompleted(500)
+                                          ));
+
+        $ys = $this->createColdObservable(array(
+                                              onNext(50, 'foo'),
+                                              onNext(100, 'bar'),
+                                              onNext(150, 'baz'),
+                                              onNext(200, 'qux'),
+                                              onCompleted(250)
+                                          ));
+
+        $results = $this->scheduler->startWithCreate(function() use ($xs, $ys) {
+            return $xs->mergeDelayError($ys);
+        });
+
+        $this->assertMessages(array(
+                                  onNext(250, 'foo'),
+                                  onNext(300, 4),
+                                  onNext(300, 'bar'),
+                                  onNext(350, 'baz'),
+                                  onNext(400, 'qux'),
+                                  onError(450, new \Exception())
+                              ), $results->getMessages());
+
+        $this->assertSubscriptions(array(subscribe(200, 360)), $xs->getSubscriptions());
+        $this->assertSubscriptions(array(subscribe(200, 450)), $ys->getSubscriptions());
+    }
+
+    /**
+     * @test
+     */
+    public function it_works_when_both_sources_error()
+    {
+        $xs = $this->createColdObservable(array(
+                                              onNext(100, 4),
+                                              onError(160, new \Exception()),
+                                              onNext(200, 2),
+                                              onNext(300, 3),
+                                              onNext(400, 1),
+                                              onCompleted(500)
+                                          ));
+
+        $ys = $this->createColdObservable(array(
+                                              onNext(50, 'foo'),
+                                              onNext(100, 'bar'),
+                                              onNext(150, 'baz'),
+                                              onError(161, new \Exception()),
+                                              onNext(200, 'qux'),
+                                              onCompleted(250)
+                                          ));
+
+        $results = $this->scheduler->startWithCreate(function() use ($xs, $ys) {
+            return $xs->mergeDelayError($ys);
+        });
+
+        $this->assertMessages(array(
+                                  onNext(250, 'foo'),
+                                  onNext(300, 4),
+                                  onNext(300, 'bar'),
+                                  onNext(350, 'baz'),
+                                  onError(361, new \Exception())
+                              ), $results->getMessages());
+
+        $this->assertSubscriptions(array(subscribe(200, 360)), $xs->getSubscriptions());
+        $this->assertSubscriptions(array(subscribe(200, 361)), $ys->getSubscriptions());
+    }
+}
\ No newline at end of file