diff --git a/Lib/heapq.py b/Lib/heapq.py
index fabefd87f8bf8c..78dd527c979e3e 100644
--- a/Lib/heapq.py
+++ b/Lib/heapq.py
@@ -329,6 +329,111 @@ def merge(*iterables, key=None, reverse=False):
 
     '''
 
+    if len(iterables) == 2:
+        # special case for performance
+
+        a_iter = iter(iterables[0])
+        b_iter = iter(iterables[1])
+        next_a = a_iter.__next__
+        next_b = b_iter.__next__
+
+        try:
+            a = next_a()
+        except StopIteration:
+            yield from b_iter
+            return
+        try:
+            b = next_b()
+        except StopIteration:
+            yield a
+            yield from a_iter
+            return
+
+        if key is None:
+            if reverse:
+                # no key, reverse
+                while True:
+                    if a < b:
+                        yield b
+                        try:
+                            b = next_b()
+                        except StopIteration:
+                            yield a
+                            yield from a_iter
+                            return
+                    else:
+                        yield a
+                        try:
+                            a = next_a()
+                        except StopIteration:
+                            yield b
+                            yield from b_iter
+                            return
+            else:
+                # no key, forward
+                while True:
+                    if b < a:
+                        yield b
+                        try:
+                            b = next_b()
+                        except StopIteration:
+                            yield a
+                            yield from a_iter
+                            return
+                    else:
+                        yield a
+                        try:
+                            a = next_a()
+                        except StopIteration:
+                            yield b
+                            yield from b_iter
+                            return
+        else:
+            ka = key(a)
+            kb = key(b)
+            if reverse:
+                # using a key, reverse
+                while True:
+                    if ka < kb:
+                        yield b
+                        try:
+                            b = next_b()
+                        except StopIteration:
+                            yield a
+                            yield from a_iter
+                            return
+                        kb = key(b)
+                    else:
+                        yield a
+                        try:
+                            a = next_a()
+                        except StopIteration:
+                            yield b
+                            yield from b_iter
+                            return
+                        ka = key(a)
+            else:
+                # using a key, forward
+                while True:
+                    if kb < ka:
+                        yield b
+                        try:
+                            b = next_b()
+                        except StopIteration:
+                            yield a
+                            yield from a_iter
+                            return
+                        kb = key(b)
+                    else:
+                        yield a
+                        try:
+                            a = next_a()
+                        except StopIteration:
+                            yield b
+                            yield from b_iter
+                            return
+                        ka = key(a)
+
     h = []
     h_append = h.append
 
diff --git a/Lib/test/test_heapq.py b/Lib/test/test_heapq.py
index 861ba7540df2bc..bf786e37fd0b29 100644
--- a/Lib/test/test_heapq.py
+++ b/Lib/test/test_heapq.py
@@ -176,22 +176,23 @@ def test_heapsort(self):
             self.assertEqual(heap_sorted, sorted(data))
 
     def test_merge(self):
-        inputs = []
-        for i in range(random.randrange(25)):
-            row = []
-            for j in range(random.randrange(100)):
-                tup = random.choice('ABC'), random.randrange(-500, 500)
-                row.append(tup)
-            inputs.append(row)
-
-        for key in [None, itemgetter(0), itemgetter(1), itemgetter(1, 0)]:
-            for reverse in [False, True]:
-                seqs = []
-                for seq in inputs:
-                    seqs.append(sorted(seq, key=key, reverse=reverse))
-                self.assertEqual(sorted(chain(*inputs), key=key, reverse=reverse),
-                                 list(self.module.merge(*seqs, key=key, reverse=reverse)))
-                self.assertEqual(list(self.module.merge()), [])
+        for n in range(26):
+            inputs = []
+            for i in range(n):
+                row = []
+                for j in range(random.randrange(100)):
+                    tup = random.choice('ABC'), random.randrange(-500, 500)
+                    row.append(tup)
+                inputs.append(row)
+
+            for key in [None, itemgetter(0), itemgetter(1), itemgetter(1, 0)]:
+                for reverse in [False, True]:
+                    seqs = []
+                    for seq in inputs:
+                        seqs.append(sorted(seq, key=key, reverse=reverse))
+                    self.assertEqual(sorted(chain(*inputs), key=key, reverse=reverse),
+                                     list(self.module.merge(*seqs, key=key, reverse=reverse)))
+                    self.assertEqual(list(self.module.merge()), [])
 
     def test_empty_merges(self):
         # Merging two empty lists (with or without a key) should produce
diff --git a/Misc/NEWS.d/next/Library/2019-12-01-04-01-32.bpo-38938.Mj9nKR.rst b/Misc/NEWS.d/next/Library/2019-12-01-04-01-32.bpo-38938.Mj9nKR.rst
new file mode 100644
index 00000000000000..88fbeec7e16759
--- /dev/null
+++ b/Misc/NEWS.d/next/Library/2019-12-01-04-01-32.bpo-38938.Mj9nKR.rst
@@ -0,0 +1 @@
+For performance, added a special case to heapq.merge for two iterables.
\ No newline at end of file