diff --git a/django/template/loader_tags.py b/django/template/loader_tags.py
index b96214cad1..07b614c270 100644
--- a/django/template/loader_tags.py
+++ b/django/template/loader_tags.py
@@ -171,7 +171,10 @@ class IncludeNode(Node):
             # If not, try the cache and select_template().
             template_name = template or ()
             if isinstance(template_name, str):
-                template_name = (template_name,)
+                template_name = (construct_relative_path(
+                    self.origin.template_name,
+                    template_name,
+                ),)
             else:
                 template_name = tuple(template_name)
             cache = context.render_context.dicts[0].setdefault(self, {})
@@ -226,7 +229,12 @@ def construct_relative_path(current_template_name, relative_name):
     Convert a relative path (starting with './' or '../') to the full template
     name based on the current_template_name.
     """
-    if not relative_name.startswith(("'./", "'../", '"./', '"../')):
+    has_quotes = (
+        (relative_name.startswith('"') and relative_name.endswith('"')) or
+        (relative_name.startswith("'") and relative_name.endswith("'"))
+    )
+    new_name = relative_name.strip('\'"')
+    if not new_name.startswith(('./', '../')):
         # relative_name is a variable or a literal that doesn't contain a
         # relative path.
         return relative_name
@@ -234,7 +242,7 @@ def construct_relative_path(current_template_name, relative_name):
     new_name = posixpath.normpath(
         posixpath.join(
             posixpath.dirname(current_template_name.lstrip('/')),
-            relative_name.strip('\'"')
+            new_name,
         )
     )
     if new_name.startswith('../'):
@@ -248,7 +256,7 @@ def construct_relative_path(current_template_name, relative_name):
             "same template in which the tag appears."
             % (relative_name, current_template_name)
         )
-    return '"%s"' % new_name
+    return f'"{new_name}"' if has_quotes else new_name
 
 
 @register.tag('extends')
diff --git a/tests/template_tests/relative_templates/dir1/dir2/inc3.html b/tests/template_tests/relative_templates/dir1/dir2/inc3.html
new file mode 100644
index 0000000000..7a8374df51
--- /dev/null
+++ b/tests/template_tests/relative_templates/dir1/dir2/inc3.html
@@ -0,0 +1 @@
+{% include tmpl %}
diff --git a/tests/template_tests/test_extends_relative.py b/tests/template_tests/test_extends_relative.py
index 9e8d7fc9b9..49a7624600 100644
--- a/tests/template_tests/test_extends_relative.py
+++ b/tests/template_tests/test_extends_relative.py
@@ -70,6 +70,12 @@ class IncludeRelativeBehaviorTests(SimpleTestCase):
         output = template.render(Context({}))
         self.assertEqual(output.strip(), 'dir2 include')
 
+    def test_normal_include_variable(self):
+        engine = Engine(dirs=[RELATIVE])
+        template = engine.get_template('dir1/dir2/inc3.html')
+        output = template.render(Context({'tmpl': './include_content.html'}))
+        self.assertEqual(output.strip(), 'dir2 include')
+
     def test_dir2_include(self):
         engine = Engine(dirs=[RELATIVE])
         template = engine.get_template('dir1/dir2/inc1.html')