diff --git a/include/llvm/PassRegistry.h b/include/llvm/PassRegistry.h
index 327a152147c..6233f24c5fd 100644
--- a/include/llvm/PassRegistry.h
+++ b/include/llvm/PassRegistry.h
@@ -78,10 +78,6 @@ public:
   /// registry.  Required in order to use the pass with a PassManager.
   void registerPass(const PassInfo &PI, bool ShouldFree = false);
 
-  /// registerPass - Unregister a pass (by means of its PassInfo) with the
-  /// registry.
-  void unregisterPass(const PassInfo &PI);
-
   /// registerAnalysisGroup - Register an analysis group (or a pass implementing
   // an analysis group) with the registry.  Like registerPass, this is required
   // in order for a PassManager to be able to use this group/pass.
diff --git a/lib/IR/PassRegistry.cpp b/lib/IR/PassRegistry.cpp
index 2d056030fa2..2cff3ccdc23 100644
--- a/lib/IR/PassRegistry.cpp
+++ b/lib/IR/PassRegistry.cpp
@@ -70,16 +70,6 @@ void PassRegistry::registerPass(const PassInfo &PI, bool ShouldFree) {
     ToFree.push_back(std::unique_ptr<const PassInfo>(&PI));
 }
 
-void PassRegistry::unregisterPass(const PassInfo &PI) {
-  sys::SmartScopedWriter<true> Guard(Lock);
-  MapType::iterator I = PassInfoMap.find(PI.getTypeInfo());
-  assert(I != PassInfoMap.end() && "Pass registered but not in map!");
-
-  // Remove pass from the map.
-  PassInfoMap.erase(I);
-  PassInfoStringMap.erase(PI.getPassArgument());
-}
-
 void PassRegistry::enumerateWith(PassRegistrationListener *L) {
   sys::SmartScopedReader<true> Guard(Lock);
   for (auto PassInfoPair : PassInfoMap)