diff --git a/src/search/PhutilSearchQueryCompiler.php b/src/search/PhutilSearchQueryCompiler.php
--- a/src/search/PhutilSearchQueryCompiler.php
+++ b/src/search/PhutilSearchQueryCompiler.php
@@ -6,9 +6,12 @@
   private $operators = '+ -><()~*:""&|';
   private $query;
   private $stemmer;
+  private $enableFunctions = false;
 
   const OPERATOR_NOT = 'not';
   const OPERATOR_AND = 'and';
+  const OPERATOR_SUBSTRING = 'sub';
+  const OPERATOR_EXACT = 'exact';
 
   public function setOperators($operators) {
     $this->operators = $operators;
@@ -28,6 +31,15 @@
     return $this->stemmer;
   }
 
+  public function setEnableFunctions($enable_functions) {
+    $this->enableFunctions = $enable_functions;
+    return $this;
+  }
+
+  public function getEnableFunctions() {
+    return $this->enableFunctions;
+  }
+
   public function compileQuery(array $tokens) {
     assert_instances_of($tokens, 'PhutilSearchQueryToken');
 
@@ -102,11 +114,21 @@
     $query = phutil_utf8v($query);
     $length = count($query);
 
+    $enable_functions = $this->getEnableFunctions();
+
     $mode = 'scan';
     $current_operator = array();
     $current_token = array();
+    $current_function = null;
     $is_quoted = false;
     $tokens = array();
+
+    if ($enable_functions) {
+      $operator_characters = '[~=+-]';
+    } else {
+      $operator_characters = '[+-]';
+    }
+
     for ($ii = 0; $ii < $length; $ii++) {
       $character = $query[$ii];
 
@@ -115,7 +137,36 @@
           continue;
         }
 
+        $mode = 'function';
+      }
+
+      if ($mode == 'function') {
         $mode = 'operator';
+
+        if ($enable_functions) {
+          $found = false;
+          for ($jj = $ii; $jj < $length; $jj++) {
+            if (preg_match('/^[a-zA-Z]\z/u', $query[$jj])) {
+              continue;
+            }
+            if ($query[$jj] == ':') {
+              $found = $jj;
+            }
+            break;
+          }
+
+          if ($found !== false) {
+            $function = array_slice($query, $ii, ($jj - $ii));
+            $current_function = implode('', $function);
+
+            if (!strlen($current_function)) {
+              $current_function = null;
+            }
+
+            $ii = $jj;
+            continue;
+          }
+        }
       }
 
       if ($mode == 'operator') {
@@ -123,7 +174,7 @@
           continue;
         }
 
-        if (preg_match('/^[+-]\z/', $character)) {
+        if (preg_match('/^'.$operator_characters.'\z/', $character)) {
           $current_operator[] = $character;
           continue;
         }
@@ -164,13 +215,21 @@
         }
 
         if ($capture) {
-          $tokens[] = array(
+          $token = array(
             'operator' => $current_operator,
             'quoted' => $was_quoted,
             'value' => $current_token,
           );
+
+          if ($enable_functions) {
+            $token['function'] = $current_function;
+          }
+
+          $tokens[] = $token;
+
           $current_operator = array();
           $current_token = array();
+          $current_function = null;
           continue;
         } else {
           $current_token[] = $character;
@@ -191,12 +250,18 @@
           implode('', $current_operator)));
     }
 
-    $tokens[] = array(
+    $token = array(
       'operator' => $current_operator,
       'quoted' => false,
       'value' => $current_token,
     );
 
+    if ($enable_functions) {
+      $token['function'] = $current_function;
+    }
+
+    $tokens[] = $token;
+
     $results = array();
     foreach ($tokens as $token) {
       $value = implode('', $token['value']);
@@ -210,6 +275,12 @@
         case '-':
           $operator = self::OPERATOR_NOT;
           break;
+        case '~':
+          $operator = self::OPERATOR_SUBSTRING;
+          break;
+        case '=':
+          $operator = self::OPERATOR_EXACT;
+          break;
         case '':
         case '+':
           $operator = self::OPERATOR_AND;
@@ -221,11 +292,17 @@
               $operator_string));
       }
 
-      $results[] = array(
+      $result = array(
         'operator' => $operator,
         'quoted' => $token['quoted'],
         'value' => $value,
       );
+
+      if ($enable_functions) {
+        $result['function'] = $token['function'];
+      }
+
+      $results[] = $result;
     }
 
     return $results;
diff --git a/src/search/PhutilSearchQueryToken.php b/src/search/PhutilSearchQueryToken.php
--- a/src/search/PhutilSearchQueryToken.php
+++ b/src/search/PhutilSearchQueryToken.php
@@ -5,6 +5,7 @@
   private $isQuoted;
   private $value;
   private $operator;
+  private $function;
 
   public static function newFromDictionary(array $dictionary) {
     $token = new self();
@@ -12,6 +13,7 @@
     $token->isQuoted = $dictionary['quoted'];
     $token->operator = $dictionary['operator'];
     $token->value = $dictionary['value'];
+    $token->function = idx($dictionary, 'function');
 
     return $token;
   }
@@ -28,4 +30,8 @@
     return $this->operator;
   }
 
+  public function getFunction() {
+    return $this->function;
+  }
+
 }
diff --git a/src/search/__tests__/PhutilSearchQueryCompilerTestCase.php b/src/search/__tests__/PhutilSearchQueryCompilerTestCase.php
--- a/src/search/__tests__/PhutilSearchQueryCompilerTestCase.php
+++ b/src/search/__tests__/PhutilSearchQueryCompilerTestCase.php
@@ -87,6 +87,43 @@
     $this->assertCompileQueries($stemming_tests, null, $stemmer);
   }
 
+  public function testCompileQueriesWithFunctions() {
+    $op_and = PhutilSearchQueryCompiler::OPERATOR_AND;
+    $op_sub = PhutilSearchQueryCompiler::OPERATOR_SUBSTRING;
+    $op_exact = PhutilSearchQueryCompiler::OPERATOR_EXACT;
+
+    $function_tests = array(
+      'cat' => array(
+        array(null, $op_and, 'cat'),
+      ),
+      ':cat' => array(
+        array(null, $op_and, 'cat'),
+      ),
+      'title:cat' => array(
+        array('title', $op_and, 'cat'),
+      ),
+      'title:cat:dog' => array(
+        array('title', $op_and, 'cat:dog'),
+      ),
+      'title:~cat' => array(
+        array('title', $op_sub, 'cat'),
+      ),
+      'cat title:="Meow Meow"' => array(
+        array(null, $op_and, 'cat'),
+        array('title', $op_exact, 'Meow Meow'),
+      ),
+      'title:cat title:dog' => array(
+        array('title', $op_and, 'cat'),
+        array('title', $op_and, 'dog'),
+      ),
+      '~"core and seven years ag"' => array(
+        array(null, $op_sub, 'core and seven years ag'),
+      ),
+    );
+
+    $this->assertCompileFunctionQueries($function_tests);
+  }
+
   private function assertCompileQueries(
     array $tests,
     $operators = null,
@@ -143,4 +180,27 @@
     }
   }
 
+  private function assertCompileFunctionQueries(array $tests) {
+    foreach ($tests as $input => $expect) {
+      $compiler = id(new PhutilSearchQueryCompiler())
+        ->setEnableFunctions(true);
+
+      $tokens = $compiler->newTokens($input);
+
+      $result = array();
+      foreach ($tokens as $token) {
+        $result[] = array(
+          $token->getFunction(),
+          $token->getOperator(),
+          $token->getValue(),
+        );
+      }
+
+      $this->assertEqual(
+        $expect,
+        $result,
+        pht('Function compilation of query: %s', $input));
+    }
+  }
+
 }