Index: include/llvm/Support/DynamicLibrary.h
===================================================================
--- include/llvm/Support/DynamicLibrary.h
+++ include/llvm/Support/DynamicLibrary.h
@@ -68,6 +68,14 @@
     static DynamicLibrary getPermanentLibrary(const char *filename,
                                               std::string *errMsg = nullptr);
 
+    /// Registers an externally loaded library. The library will be unloaded
+    /// when the program terminates.
+    ///
+    /// It is safe to call this function multiple times for the same library.
+    ///
+    /// \returns An empty \p DynamicLibrary on failure.
+    static DynamicLibrary addPermanentLibrary(void *handle);
+
     /// This function permanently loads the dynamic library at the given path.
     /// Use this instead of getPermanentLibrary() when you won't need to get
     /// symbols from the library itself.
Index: lib/Support/DynamicLibrary.cpp
===================================================================
--- lib/Support/DynamicLibrary.cpp
+++ lib/Support/DynamicLibrary.cpp
@@ -9,8 +9,6 @@
 //
 //  This file implements the operating system DynamicLibrary concept.
 //
-// FIXME: This file leaks ExplicitSymbols and OpenedHandles!
-//
 //===----------------------------------------------------------------------===//
 
 #include "llvm/Support/DynamicLibrary.h"
@@ -51,7 +49,7 @@
 //===          independent code.
 //===----------------------------------------------------------------------===//
 
-static DenseSet<void *> *OpenedHandles = nullptr;
+static llvm::ManagedStatic<DenseSet<void *> > OpenedHandles;
 
 DynamicLibrary DynamicLibrary::getPermanentLibrary(const char *filename,
                                                    std::string *errMsg) {
@@ -69,14 +67,15 @@
   if (!filename)
     handle = RTLD_DEFAULT;
 #endif
+  return addPermanentLibrary(handle);
+}
 
-  if (!OpenedHandles)
-    OpenedHandles = new DenseSet<void *>();
+DynamicLibrary DynamicLibrary::addPermanentLibrary(void *handle) {
+  SmartScopedLock<true> lock(*SymbolsMutex);
 
-  // If we've already loaded this library, dlclose() the handle in order to
-  // keep the internal refcount at +1.
+  // If we've already loaded this library, tell the caller.
   if (!OpenedHandles->insert(handle).second)
-    dlclose(handle);
+    return DynamicLibrary();
 
   return DynamicLibrary(handle);
 }
@@ -121,7 +120,7 @@
 
 #if defined(HAVE_DLFCN_H) && defined(HAVE_DLOPEN)
   // Now search the libraries.
-  if (OpenedHandles) {
+  if (OpenedHandles.isConstructed()) {
     for (DenseSet<void *>::iterator I = OpenedHandles->begin(),
          E = OpenedHandles->end(); I != E; ++I) {
       //lt_ptr ptr = lt_dlsym(*I, symbolName);
Index: lib/Support/Windows/DynamicLibrary.inc
===================================================================
--- lib/Support/Windows/DynamicLibrary.inc
+++ lib/Support/Windows/DynamicLibrary.inc
@@ -9,6 +9,8 @@
 //
 // This file provides the Win32 specific implementation of DynamicLibrary.
 //
+// FIXME: This file leaks OpenedHandles!
+//
 //===----------------------------------------------------------------------===//
 
 #include "WindowsSupport.h"
@@ -98,6 +100,18 @@
   return DynamicLibrary(a_handle);
 }
 
+DynamicLibrary DynamicLibrary::addPermanentLibrary(void *handle) {
+  SmartScopedLock<true> lock(*SymbolsMutex);
+  if (OpenedHandles == 0)
+    OpenedHandles = new DenseSet<HMODULE>();
+
+  // If we've already loaded this library, tell the caller.
+  if (!OpenedHandles->insert((const HMODULE)handle).second)
+    return DynamicLibrary();
+
+  return DynamicLibrary((HMODULE)handle);
+}
+
 // Stack probing routines are in the support library (e.g. libgcc), but we don't
 // have dynamic linking on windows. Provide a hook.
 #define EXPLICIT_SYMBOL(SYM)                    \