diff --git a/src/__phutil_library_map__.php b/src/__phutil_library_map__.php
index 65f00f2c..ae832c38 100644
--- a/src/__phutil_library_map__.php
+++ b/src/__phutil_library_map__.php
@@ -57,6 +57,8 @@ phutil_register_library_map(array(
     'ArcanistClassExtendsObjectXHPASTLinterRule' => 'lint/linter/xhpast/rules/ArcanistClassExtendsObjectXHPASTLinterRule.php',
     'ArcanistClassExtendsObjectXHPASTLinterRuleTestCase' => 'lint/linter/xhpast/rules/__tests__/ArcanistClassExtendsObjectXHPASTLinterRuleTestCase.php',
     'ArcanistClassFilenameMismatchXHPASTLinterRule' => 'lint/linter/xhpast/rules/ArcanistClassFilenameMismatchXHPASTLinterRule.php',
+    'ArcanistClassMustBeDeclaredAbstractXHPASTLinterRule' => 'lint/linter/xhpast/rules/ArcanistClassMustBeDeclaredAbstractXHPASTLinterRule.php',
+    'ArcanistClassMustBeDeclaredAbstractXHPASTLinterRuleTestCase' => 'lint/linter/xhpast/rules/__tests__/ArcanistClassMustBeDeclaredAbstractXHPASTLinterRuleTestCase.php',
     'ArcanistClassNameLiteralXHPASTLinterRule' => 'lint/linter/xhpast/rules/ArcanistClassNameLiteralXHPASTLinterRule.php',
     'ArcanistClassNameLiteralXHPASTLinterRuleTestCase' => 'lint/linter/xhpast/rules/__tests__/ArcanistClassNameLiteralXHPASTLinterRuleTestCase.php',
     'ArcanistCloseRevisionWorkflow' => 'workflow/ArcanistCloseRevisionWorkflow.php',
@@ -441,6 +443,8 @@ phutil_register_library_map(array(
     'ArcanistClassExtendsObjectXHPASTLinterRule' => 'ArcanistXHPASTLinterRule',
     'ArcanistClassExtendsObjectXHPASTLinterRuleTestCase' => 'ArcanistXHPASTLinterRuleTestCase',
     'ArcanistClassFilenameMismatchXHPASTLinterRule' => 'ArcanistXHPASTLinterRule',
+    'ArcanistClassMustBeDeclaredAbstractXHPASTLinterRule' => 'ArcanistXHPASTLinterRule',
+    'ArcanistClassMustBeDeclaredAbstractXHPASTLinterRuleTestCase' => 'ArcanistXHPASTLinterRuleTestCase',
     'ArcanistClassNameLiteralXHPASTLinterRule' => 'ArcanistXHPASTLinterRule',
     'ArcanistClassNameLiteralXHPASTLinterRuleTestCase' => 'ArcanistXHPASTLinterRuleTestCase',
     'ArcanistCloseRevisionWorkflow' => 'ArcanistWorkflow',
diff --git a/src/lint/linter/xhpast/rules/ArcanistClassMustBeDeclaredAbstractXHPASTLinterRule.php b/src/lint/linter/xhpast/rules/ArcanistClassMustBeDeclaredAbstractXHPASTLinterRule.php
new file mode 100644
index 00000000..1d3b4f6e
--- /dev/null
+++ b/src/lint/linter/xhpast/rules/ArcanistClassMustBeDeclaredAbstractXHPASTLinterRule.php
@@ -0,0 +1,74 @@
+<?php
+
+final class ArcanistClassMustBeDeclaredAbstractXHPASTLinterRule
+  extends ArcanistXHPASTLinterRule {
+
+  const ID = 113;
+
+  public function getLintName() {
+    return pht(
+      '`%s` Containing `%s` Methods Must Be Declared `%s`',
+      'class',
+      'abstract',
+      'abstract');
+  }
+
+  public function process(XHPASTNode $root) {
+    $classes = $root->selectDescendantsOfType('n_CLASS_DECLARATION');
+
+    foreach ($classes as $class) {
+      $class_modifiers = $this->getModifiers($class);
+
+      $abstract_methods = array();
+      $methods = $class->selectDescendantsOfType('n_METHOD_DECLARATION');
+
+      foreach ($methods as $method) {
+        $method_modifiers = $this->getModifiers($method);
+
+        if (idx($method_modifiers, 'abstract')) {
+          $abstract_methods[] = $method;
+        }
+      }
+
+      if (!idx($class_modifiers, 'abstract') && $abstract_methods) {
+        $this->raiseLintAtNode(
+          $class,
+          pht(
+            'Class contains %s %s method(s) and must therefore '.
+            'be declared `%s`.',
+            phutil_count($abstract_methods),
+            'abstract',
+            'abstract'));
+      }
+    }
+  }
+
+  /**
+   * Get class/method modifiers.
+   *
+   * @param  XHPASTNode         A node of type `n_CLASS_DECLARATION` or
+   *                            `n_METHOD_DECLARATION`.
+   * @return map<string, bool>  Class/method modifiers.
+   */
+  private function getModifiers(XHPASTNode $node) {
+    $modifier_list = $node->getChildByIndex(0);
+
+    switch ($modifier_list->getTypeName()) {
+      case 'n_CLASS_ATTRIBUTES':
+      case 'n_METHOD_MODIFIER_LIST':
+        break;
+
+      default:
+        return array();
+    }
+
+    $modifiers = array();
+
+    foreach ($modifier_list->selectDescendantsOfType('n_STRING') as $modifier) {
+      $modifiers[strtolower($modifier->getConcreteString())] = true;
+    }
+
+    return $modifiers;
+  }
+
+}
diff --git a/src/lint/linter/xhpast/rules/__tests__/ArcanistClassMustBeDeclaredAbstractXHPASTLinterRuleTestCase.php b/src/lint/linter/xhpast/rules/__tests__/ArcanistClassMustBeDeclaredAbstractXHPASTLinterRuleTestCase.php
new file mode 100644
index 00000000..ae34b95f
--- /dev/null
+++ b/src/lint/linter/xhpast/rules/__tests__/ArcanistClassMustBeDeclaredAbstractXHPASTLinterRuleTestCase.php
@@ -0,0 +1,11 @@
+<?php
+
+final class ArcanistClassMustBeDeclaredAbstractXHPASTLinterRuleTestCase
+  extends ArcanistXHPASTLinterRuleTestCase {
+
+  public function testLinter() {
+    $this->executeTestsInDirectory(
+      dirname(__FILE__).'/class-must-be-declared-abstract/');
+  }
+
+}
diff --git a/src/lint/linter/xhpast/rules/__tests__/class-must-be-declared-abstract/is-abstract.lint-test b/src/lint/linter/xhpast/rules/__tests__/class-must-be-declared-abstract/is-abstract.lint-test
new file mode 100644
index 00000000..c2307f9c
--- /dev/null
+++ b/src/lint/linter/xhpast/rules/__tests__/class-must-be-declared-abstract/is-abstract.lint-test
@@ -0,0 +1,5 @@
+<?php
+abstract class SomeClass {
+  abstract public function someMethod();
+}
+~~~~~~~~~~
diff --git a/src/lint/linter/xhpast/rules/__tests__/class-must-be-declared-abstract/is-not-abstract.lint-test b/src/lint/linter/xhpast/rules/__tests__/class-must-be-declared-abstract/is-not-abstract.lint-test
new file mode 100644
index 00000000..1d2c7788
--- /dev/null
+++ b/src/lint/linter/xhpast/rules/__tests__/class-must-be-declared-abstract/is-not-abstract.lint-test
@@ -0,0 +1,5 @@
+<?php
+class SomeClass {
+  public function someMethod();
+}
+~~~~~~~~~~
diff --git a/src/lint/linter/xhpast/rules/__tests__/class-must-be-declared-abstract/should-be-abstract.lint-test b/src/lint/linter/xhpast/rules/__tests__/class-must-be-declared-abstract/should-be-abstract.lint-test
new file mode 100644
index 00000000..90861196
--- /dev/null
+++ b/src/lint/linter/xhpast/rules/__tests__/class-must-be-declared-abstract/should-be-abstract.lint-test
@@ -0,0 +1,6 @@
+<?php
+class SomeClass {
+  abstract public function someMethod();
+}
+~~~~~~~~~~
+error:2:1