diff --git a/lib/options/SchemaStringOptions.js b/lib/options/SchemaStringOptions.js
index 11e8848a787..8c6bb0ac067 100644
--- a/lib/options/SchemaStringOptions.js
+++ b/lib/options/SchemaStringOptions.js
@@ -88,6 +88,32 @@ Object.defineProperty(SchemaStringOptions.prototype, 'trim', opts);
 
 Object.defineProperty(SchemaStringOptions.prototype, 'uppercase', opts);
 
+/**
+ * If set, Mongoose will add a custom validator that ensures the given
+ * string's `length` is at least the given number.
+ *
+ * @api public
+ * @property minlength
+ * @memberOf SchemaStringOptions
+ * @type Number
+ * @instance
+ */
+
+Object.defineProperty(SchemaStringOptions.prototype, 'minlength', opts);
+
+/**
+ * If set, Mongoose will add a custom validator that ensures the given
+ * string's `length` is at most the given number.
+ *
+ * @api public
+ * @property maxlength
+ * @memberOf SchemaStringOptions
+ * @type Number
+ * @instance
+ */
+
+Object.defineProperty(SchemaStringOptions.prototype, 'maxlength', opts);
+
 /*!
  * ignore
  */
diff --git a/lib/schema/string.js b/lib/schema/string.js
index fe3e9568a07..645c4c3571e 100644
--- a/lib/schema/string.js
+++ b/lib/schema/string.js
@@ -43,7 +43,12 @@ SchemaString.schemaName = 'String';
  */
 SchemaString.prototype = Object.create(SchemaType.prototype);
 SchemaString.prototype.constructor = SchemaString;
-SchemaString.prototype.OptionsConstructor = SchemaStringOptions;
+Object.defineProperty(SchemaString.prototype, 'OptionsConstructor', {
+  configurable: false,
+  enumerable: false,
+  writable: false,
+  value: SchemaStringOptions
+});
 
 /*!
  * ignore
@@ -574,17 +579,23 @@ function handleArray(val) {
   });
 }
 
-SchemaString.prototype.$conditionalHandlers =
-    utils.options(SchemaType.prototype.$conditionalHandlers, {
-      $all: handleArray,
-      $gt: handleSingle,
-      $gte: handleSingle,
-      $lt: handleSingle,
-      $lte: handleSingle,
-      $options: String,
-      $regex: handleSingle,
-      $not: handleSingle
-    });
+const $conditionalHandlers = utils.options(SchemaType.prototype.$conditionalHandlers, {
+  $all: handleArray,
+  $gt: handleSingle,
+  $gte: handleSingle,
+  $lt: handleSingle,
+  $lte: handleSingle,
+  $options: String,
+  $regex: handleSingle,
+  $not: handleSingle
+});
+
+Object.defineProperty(SchemaString.prototype, '$conditionalHandlers', {
+  configurable: false,
+  enumerable: false,
+  writable: false,
+  value: Object.freeze($conditionalHandlers)
+});
 
 /**
  * Casts contents for queries.
diff --git a/test/schema.test.js b/test/schema.test.js
index 02c6c22baa9..7b4d6435c87 100644
--- a/test/schema.test.js
+++ b/test/schema.test.js
@@ -2135,4 +2135,13 @@ describe('schema', function() {
     assert.strictEqual(schema.path('name').isRequired, false);
     assert.strictEqual(schema.path('age').isRequired, false);
   });
+
+  it('SchemaStringOptions line up with schema/string (gh-8256)', function() {
+    const SchemaStringOptions = require('../lib/options/SchemaStringOptions');
+    const keys = Object.keys(SchemaStringOptions.prototype).
+      filter(key => key !== 'constructor');
+    const functions = Object.keys(Schema.Types.String.prototype).
+      filter(key => !['constructor', 'cast', 'castForQuery', 'checkRequired'].includes(key));
+    assert.deepEqual(keys.sort(), functions.sort());
+  });
 });