diff --git a/bin/systemlib.php b/bin/systemlib.php
index 91519efea..f2d777c23 100644
--- a/bin/systemlib.php
+++ b/bin/systemlib.php
@@ -5135,6 +5135,51 @@ class ReflectionClass implements Reflector {
   public function getAttributesRecursive() {
     return $this->fetch('attributes_rec');
   }
+
+// Do NOT modifiy this doc comment block generated by idl/sysdoc.php
+/**
+ * ( excerpt from http://www.php.net/manual/en/reflectionclass.innamespace.php )
+ *
+ * Checks if in namespace
+ *
+ * @return     bool   Returns TRUE on success or FALSE on failure.
+ */
+  public function inNamespace() {
+    return strrpos($this->getName(), '\\') !== false;
+  }
+
+// Do NOT modifiy this doc comment block generated by idl/sysdoc.php
+/**
+ * ( excerpt from http://php.net/manual/en/reflectionclass.getnamespacename.php )
+ *
+ * Gets namespace name
+ *
+ * @return     string   The namespace name.
+ */
+  public function getNamespaceName() {
+    $pos = strrpos($this->getName(), '\\');
+    if ($pos === false) {
+      return '';
+    }
+    return substr($this->getName(), 0, $pos);
+  }
+
+// Do NOT modifiy this doc comment block generated by idl/sysdoc.php
+/**
+ * ( excerpt from http://www.php.net/manual/en/reflectionclass.getshortname.php )
+ *
+ * Gets short name
+ *
+ * @return     string   The class short name.
+ */
+  public function getShortName() {
+    $pos = strrpos($this->getName(), '\\');
+    if ($pos === false) {
+      return $this->getName();
+    }
+    return substr($this->getName(), $pos + 1);
+  }
+
 }
 
 ///////////////////////////////////////////////////////////////////////////////
diff --git a/hphp/compiler/analysis/analysis_result.cpp b/hphp/compiler/analysis/analysis_result.cpp
index d5571ea6a..a8e91bba4 100644
--- a/hphp/compiler/analysis/analysis_result.cpp
+++ b/hphp/compiler/analysis/analysis_result.cpp
@@ -14,12 +14,13 @@
    +----------------------------------------------------------------------+
 */
 
+#include "hphp/compiler/analysis/analysis_result.h"
+
 #include <iomanip>
 #include <algorithm>
 #include <sstream>
 #include <boost/format.hpp>
 #include <boost/bind.hpp>
-#include "hphp/compiler/analysis/analysis_result.h"
 #include "hphp/compiler/analysis/alias_manager.h"
 #include "hphp/compiler/analysis/file_scope.h"
 #include "hphp/compiler/analysis/class_scope.h"
@@ -169,7 +170,7 @@ FunctionScopePtr AnalysisResult::findFunction(
   const std::string &funcName) const {
   StringToFunctionScopePtrMap::const_iterator bit =
     m_functions.find(funcName);
-  if (bit != m_functions.end() && !bit->second->ignoreRedefinition()) {
+  if (bit != m_functions.end() && !bit->second->allowOverride()) {
     return bit->second;
   }
   StringToFunctionScopePtrMap::const_iterator iter =
@@ -345,7 +346,7 @@ bool AnalysisResult::declareFunction(FunctionScopePtr funcScope) const {
   // System functions override
   auto it = m_functions.find(fname);
   if (it != m_functions.end()) {
-    if (!it->second->ignoreRedefinition()) {
+    if (!it->second->allowOverride()) {
       // we need someone to hold on to a reference to it
       // even though we're not going to do anything with it
       this->lock()->m_ignoredScopes.push_back(funcScope);
diff --git a/hphp/compiler/analysis/emitter.cpp b/hphp/compiler/analysis/emitter.cpp
index ff967b871..5ea4a63f5 100644
--- a/hphp/compiler/analysis/emitter.cpp
+++ b/hphp/compiler/analysis/emitter.cpp
@@ -5873,7 +5873,7 @@ bool EmitterVisitor::canEmitBuiltinCall(FunctionCallPtr fn,
       return false;
     }
     // in sandbox mode, don't emit FCallBuiltin for redefinable functions
-    if (func->ignoreRedefinition() && !Option::WholeProgram) {
+    if (func->allowOverride() && !Option::WholeProgram) {
       return false;
     }
     return true;
diff --git a/hphp/compiler/analysis/file_scope.h b/hphp/compiler/analysis/file_scope.h
index 7532fe032..e5341dfba 100644
--- a/hphp/compiler/analysis/file_scope.h
+++ b/hphp/compiler/analysis/file_scope.h
@@ -59,7 +59,7 @@ public:
     MixedVariableArgument     = 0x800, // variable args, may or may not be ref'd
     IsFoldable                = 0x1000,// function can be constant folded
     NeedsActRec               = 0x2000,// builtin function needs ActRec
-    IgnoreRedefinition        = 0x4000,// ignore redefinition of builtin function
+    AllowOverride             = 0x4000,// allow override of systemlib or builtin
   };
 
   typedef boost::adjacency_list<boost::setS, boost::vecS> Graph;
diff --git a/hphp/compiler/analysis/function_scope.cpp b/hphp/compiler/analysis/function_scope.cpp
index 4e2dbbc08..f1fd6754c 100644
--- a/hphp/compiler/analysis/function_scope.cpp
+++ b/hphp/compiler/analysis/function_scope.cpp
@@ -302,8 +302,8 @@ bool FunctionScope::isVariableArgument() const {
   return res;
 }
 
-bool FunctionScope::ignoreRedefinition() const {
-  return m_attribute & FileScope::IgnoreRedefinition;
+bool FunctionScope::allowOverride() const {
+  return m_attribute & FileScope::AllowOverride;
 }
 
 bool FunctionScope::isReferenceVariableArgument() const {
@@ -378,8 +378,8 @@ void FunctionScope::setVariableArgument(int reference) {
   }
 }
 
-void FunctionScope::setIgnoreRedefinition() {
-  m_attribute |= FileScope::IgnoreRedefinition;
+void FunctionScope::setAllowOverride() {
+  m_attribute |= FileScope::AllowOverride;
 }
 
 bool FunctionScope::hasEffect() const {
diff --git a/hphp/compiler/analysis/function_scope.h b/hphp/compiler/analysis/function_scope.h
index f4bc2746d..f401a3a83 100644
--- a/hphp/compiler/analysis/function_scope.h
+++ b/hphp/compiler/analysis/function_scope.h
@@ -222,10 +222,10 @@ public:
   void setNeedsActRec();
 
   /*
-   * If this is a builtin and can be redefined
+   * If this is a builtin (C++ or PHP) and can be redefined
    */
-  bool ignoreRedefinition() const;
-  void setIgnoreRedefinition();
+  bool allowOverride() const;
+  void setAllowOverride();
 
   /**
    * Whether this function is a runtime helper function
diff --git a/hphp/compiler/builtin_symbols.cpp b/hphp/compiler/builtin_symbols.cpp
index c8917cf1c..cee047bd6 100644
--- a/hphp/compiler/builtin_symbols.cpp
+++ b/hphp/compiler/builtin_symbols.cpp
@@ -203,8 +203,8 @@ FunctionScopePtr BuiltinSymbols::ImportFunctionScopePtr(AnalysisResultPtr ar,
   if (attrs & ClassInfo::NeedsActRec) {
     f->setNeedsActRec();
   }
-  if ((attrs & ClassInfo::IgnoreRedefinition) && !isMethod) {
-    f->setIgnoreRedefinition();
+  if ((attrs & ClassInfo::AllowOverride) && !isMethod) {
+    f->setAllowOverride();
   }
 
   FunctionScope::RecordFunctionInfo(f->getName(), f);
diff --git a/hphp/idl/base.php b/hphp/idl/base.php
index b519af937..6232b283c 100644
--- a/hphp/idl/base.php
+++ b/hphp/idl/base.php
@@ -121,7 +121,7 @@ define('IsFinal',                        1 <<  5);
 define('IsPublic',                       1 <<  6);
 define('IsProtected',                    1 <<  7);
 define('IsPrivate',                      1 <<  8);
-define('IgnoreRedefinition',             1 <<  8);
+define('AllowOverride',                  1 <<  8);
 define('IsStatic',                       1 <<  9);
 // FIXME (#2163116): IsInherited = (1 << 10) in base_class.h
 define('IsCppAbstract',                  1 << 10);
@@ -162,7 +162,7 @@ function get_flag_names($arr, $name, $global_func) {
   if ($flag & IsPublic              ) $ret .= ' | IsPublic'              ;
   if ($flag & IsProtected           ) $ret .= ' | IsProtected'           ;
   if ($global_func) {
-    if ($flag & IgnoreRedefinition  ) $ret .= ' | IgnoreRedefinition'    ;
+    if ($flag & AllowOverride       ) $ret .= ' | AllowOverride'         ;
   } else {
     if ($flag & IsPrivate           ) $ret .= ' | IsPrivate'             ;
   }
diff --git a/hphp/runtime/base/class_info.h b/hphp/runtime/base/class_info.h
index 953b1f861..88195f717 100644
--- a/hphp/runtime/base/class_info.h
+++ b/hphp/runtime/base/class_info.h
@@ -52,7 +52,7 @@ public:
     IsInherited            = (1 << 10), //                         x
     HasCall                = IsPublic,  //    x
     HasCallStatic          = IsProtected,//   x
-    IgnoreRedefinition     = IsPrivate, //                  x
+    AllowOverride          = IsPrivate, //                  x
     IsReference            = (1 << 11), //                  x      x     x
     IsConstructor          = (1 << 12), //                         x
 
diff --git a/hphp/runtime/vm/func.cpp b/hphp/runtime/vm/func.cpp
index ef125e3fe..ac7ca3794 100644
--- a/hphp/runtime/vm/func.cpp
+++ b/hphp/runtime/vm/func.cpp
@@ -654,6 +654,11 @@ void Func::setCached() {
   setCachedFunc(this, isDebuggerAttached());
 }
 
+bool Func::isAllowOverride() const {
+  return shared()->m_info &&
+    (shared()->m_info->attribute & ClassInfo::AllowOverride);
+}
+
 const Func* Func::getGeneratorBody(const StringData* name) const {
   if (isNonClosureMethod()) {
     return cls()->lookupMethod(name);
diff --git a/hphp/runtime/vm/func.h b/hphp/runtime/vm/func.h
index adf682bfb..2601b0691 100644
--- a/hphp/runtime/vm/func.h
+++ b/hphp/runtime/vm/func.h
@@ -347,10 +347,7 @@ struct Func {
   bool hasStaticLocals() const { return !shared()->m_staticVars.empty(); }
   int numStaticLocals() const { return shared()->m_staticVars.size(); }
   const ClassInfo::MethodInfo* info() const { return shared()->m_info; }
-  bool isIgnoreRedefinition() const {
-    return shared()->m_info &&
-    (shared()->m_info->attribute & ClassInfo::IgnoreRedefinition);
-  }
+  bool isAllowOverride() const;
   const BuiltinFunction& nativeFuncPtr() const {
     return shared()->m_nativeFuncPtr;
   }
diff --git a/hphp/runtime/vm/func_inline.h b/hphp/runtime/vm/func_inline.h
index 22b66735b..eebc37ae3 100644
--- a/hphp/runtime/vm/func_inline.h
+++ b/hphp/runtime/vm/func_inline.h
@@ -29,7 +29,7 @@ inline ALWAYS_INLINE void setCachedFunc(Func* func, bool debugger) {
   Func** funcAddr = getCachedFuncAddr(func->getCachedOffset());
   if (UNLIKELY(*funcAddr != nullptr)) {
     if (*funcAddr == func) return;
-    if (!(*funcAddr)->isIgnoreRedefinition()) {
+    if (!(*funcAddr)->isAllowOverride()) {
       raise_error(Strings::FUNCTION_ALREADY_DEFINED, func->name()->data());
     }
   }
diff --git a/hphp/runtime/vm/funcdict.cpp b/hphp/runtime/vm/funcdict.cpp
index 4f973b525..9a430314c 100644
--- a/hphp/runtime/vm/funcdict.cpp
+++ b/hphp/runtime/vm/funcdict.cpp
@@ -14,12 +14,13 @@
    +----------------------------------------------------------------------+
 */
 
+#include "hphp/runtime/vm/funcdict.h"
+
 #include "hphp/runtime/base/runtime_option.h"
 #include "hphp/util/base.h"
 
 #include "hphp/runtime/base/execution_context.h"
 #include "hphp/runtime/ext_hhvm/ext_hhvm.h"
-#include "hphp/runtime/vm/funcdict.h"
 #include "hphp/runtime/vm/translator/translator.h"
 #include "hphp/runtime/vm/translator/targetcache.h"
 #include "hphp/runtime/vm/unit.h"
@@ -57,7 +58,7 @@ bool RenamedFuncDict::rename(const StringData* old, const StringData* n3w) {
   if (fnew && fnew != func) {
     // To match hphpc, we silently ignore functions defined in user code that
     // have the same name as a function defined in a separable extension
-    if (!fnew->isIgnoreRedefinition()) {
+    if (!fnew->isAllowOverride()) {
       raise_error("Function already defined: %s", n3w->data());
     } else {
       return false;