diff --git a/src/parser/PhutilURI.php b/src/parser/PhutilURI.php
--- a/src/parser/PhutilURI.php
+++ b/src/parser/PhutilURI.php
@@ -27,7 +27,7 @@
   const TYPE_URI = 'uri';
   const TYPE_GIT = 'git';
 
-  public function __construct($uri) {
+  public function __construct($uri, $params = array()) {
     if ($uri instanceof PhutilURI) {
       $this->protocol = $uri->protocol;
       $this->user = $uri->user;
@@ -41,7 +41,7 @@
       return;
     }
 
-    $uri = (string)$uri;
+    $uri = phutil_string_cast($uri);
 
     $type = self::TYPE_URI;
 
@@ -134,6 +134,8 @@
     $this->fragment = idx($parts, 'fragment', '');
 
     $this->type = $type;
+
+    $this->initializeQueryParams($uri, $params);
   }
 
   public function __toString() {
@@ -297,6 +299,35 @@
     return $this->insertQueryParam($key, $value);
   }
 
+  public function removeAllQueryParams() {
+    $this->query = array();
+    return $this;
+  }
+
+  public function removeQueryParam($remove_key) {
+    list($remove_key) = phutil_http_parameter_pair($remove_key, '');
+
+    foreach ($this->query as $idx => $pair) {
+      list($key, $value) = $pair;
+
+      if ($key !== $remove_key) {
+        continue;
+      }
+
+      unset($this->query[$idx]);
+    }
+
+    $this->query = array_values($this->query);
+
+    return $this;
+  }
+
+  public function replaceQueryParam($replace_key, $replace_value) {
+    $this->removeQueryParam($replace_key);
+    $this->appendQueryParam($replace_key, $replace_value);
+    return $this;
+  }
+
   private function insertQueryParam($key, $value, $idx = null) {
     list($key, $value) = phutil_http_parameter_pair($key, $value);
 
@@ -309,6 +340,38 @@
     return $this;
   }
 
+  private function initializeQueryParams($uri, array $params) {
+    $have_params = array();
+    foreach ($this->query as $pair) {
+      list($key) = $pair;
+      $have_params[$key] = true;
+    }
+
+    foreach ($params as $key => $value) {
+      if (isset($have_params[$key])) {
+        throw new InvalidArgumentException(
+          pht(
+            'Parameters specified when initializing PhutilURI collide with '.
+            'parameters in the query string: both the query string (for "%s") '.
+            'and the parameter map specify a parameter named "%s". When '.
+            'initializing a URI, parameters may not be duplicated across the '.
+            'query string and parameter map because intent (append or '.
+            'replace?) is ambiguous. Instead, construct the URI without '.
+            'parameters, then explicitly append or replace parameters.',
+            $uri,
+            $key));
+      }
+
+      if ($value === null) {
+        continue;
+      }
+
+      $this->appendQueryParam($key, $value);
+    }
+
+    return $this;
+  }
+
   public function setProtocol($protocol) {
     $this->protocol = $protocol;
     return $this;
diff --git a/src/utils/utils.php b/src/utils/utils.php
--- a/src/utils/utils.php
+++ b/src/utils/utils.php
@@ -1623,7 +1623,7 @@
       $ex);
   }
 
-  $key = (string)$key;
+  $key = phutil_string_cast($key);
 
   try {
     assert_stringlike($value);
@@ -1635,7 +1635,7 @@
       $ex);
   }
 
-  $value = (string)$value;
+  $value = phutil_string_cast($value);
 
   return array($key, $value);
 }