diff --git a/llvm/lib/Support/DynamicLibrary.cpp b/llvm/lib/Support/DynamicLibrary.cpp
index 1541a57..22fb3f2 100644
--- a/llvm/lib/Support/DynamicLibrary.cpp
+++ b/llvm/lib/Support/DynamicLibrary.cpp
@@ -20,164 +20,169 @@
 #include "llvm/Support/Mutex.h"
 #include <cstdio>
 #include <cstring>
-#include <vector>
 
-using namespace llvm;
-using namespace llvm::sys;
-
-// All methods for HandleSet should be used holding SymbolsMutex.
-class DynamicLibrary::HandleSet {
-  typedef std::vector<void *> HandleList;
-  HandleList Handles;
-  void *Process;
-
-public:
-  static void *DLOpen(const char *Filename, std::string *Err);
-  static void DLClose(void *Handle);
-  static void *DLSym(void *Handle, const char *Symbol);
-
-  HandleSet() : Process(nullptr) {}
-  ~HandleSet();
-
-  HandleList::iterator Find(void *Handle) {
-    return std::find(Handles.begin(), Handles.end(), Handle);
-  }
-
-  bool Contains(void *Handle) {
-    return Handle == Process || Find(Handle) != Handles.end();
-  }
-
-  bool AddLibrary(void *Handle, bool IsProcess = false, bool CanClose = true) {
-#ifdef LLVM_ON_WIN32
-    assert((Handle == this ? IsProcess : !IsProcess) && "Bad Handle.");
-#endif
-
-    if (LLVM_LIKELY(!IsProcess)) {
-      if (Find(Handle) != Handles.end()) {
-        if (CanClose)
-          DLClose(Handle);
-        return false;
-      }
-      Handles.push_back(Handle);
-    } else {
-#ifndef LLVM_ON_WIN32
-      if (Process) {
-        if (CanClose)
-          DLClose(Process);
-        if (Process == Handle)
-          return false;
-      }
-#endif
-      Process = Handle;
-    }
-    return true;
-  }
-
-  void *Lookup(const char *Symbol) {
-    // Process handle gets first try.
-    if (Process) {
-      if (void *Ptr = DLSym(Process, Symbol))
-        return Ptr;
-#ifndef NDEBUG
-      for (void *Handle : Handles)
-        assert(!DLSym(Handle, Symbol) && "Symbol exists in non process handle");
-#endif
-    } else {
-      // Iterate in reverse, so newer libraries/symbols override older.
-      for (auto &&I = Handles.rbegin(), E = Handles.rend(); I != E; ++I) {
-        if (void *Ptr = DLSym(*I, Symbol))
-          return Ptr;
-      }
-    }
-    return nullptr;
-  }
-};
-
-namespace {
 // Collection of symbol name/value pairs to be searched prior to any libraries.
-static llvm::ManagedStatic<llvm::StringMap<void *>> ExplicitSymbols;
-// Collection of known library handles.
-static llvm::ManagedStatic<DynamicLibrary::HandleSet> OpenedHandles;
-// Lock for ExplicitSymbols and OpenedHandles.
-static llvm::ManagedStatic<llvm::sys::SmartMutex<true>> SymbolsMutex;
+static llvm::ManagedStatic<llvm::StringMap<void *> > ExplicitSymbols;
+static llvm::ManagedStatic<llvm::sys::SmartMutex<true> > SymbolsMutex;
+
+void llvm::sys::DynamicLibrary::AddSymbol(StringRef symbolName,
+                                          void *symbolValue) {
+  SmartScopedLock<true> lock(*SymbolsMutex);
+  (*ExplicitSymbols)[symbolName] = symbolValue;
 }
 
+char llvm::sys::DynamicLibrary::Invalid = 0;
+
 #ifdef LLVM_ON_WIN32
 
 #include "Windows/DynamicLibrary.inc"
 
 #else
 
-#include "Unix/DynamicLibrary.inc"
+#if defined(HAVE_DLFCN_H) && defined(HAVE_DLOPEN)
+#include <dlfcn.h>
+using namespace llvm;
+using namespace llvm::sys;
+
+//===----------------------------------------------------------------------===//
+//=== WARNING: Implementation here must contain only TRULY operating system
+//===          independent code.
+//===----------------------------------------------------------------------===//
+
+static llvm::ManagedStatic<DenseSet<void *> > OpenedHandles;
+
+DynamicLibrary DynamicLibrary::getPermanentLibrary(const char *filename,
+                                                   std::string *errMsg) {
+  SmartScopedLock<true> lock(*SymbolsMutex);
+
+  void *handle = dlopen(filename, RTLD_LAZY|RTLD_GLOBAL);
+  if (!handle) {
+    if (errMsg) *errMsg = dlerror();
+    return DynamicLibrary();
+  }
+
+#ifdef __CYGWIN__
+  // Cygwin searches symbols only in the main
+  // with the handle of dlopen(NULL, RTLD_GLOBAL).
+  if (!filename)
+    handle = RTLD_DEFAULT;
+#endif
+
+  // If we've already loaded this library, dlclose() the handle in order to
+  // keep the internal refcount at +1.
+  if (!OpenedHandles->insert(handle).second)
+    dlclose(handle);
+
+  return DynamicLibrary(handle);
+}
+
+DynamicLibrary DynamicLibrary::addPermanentLibrary(void *handle,
+                                                   std::string *errMsg) {
+  SmartScopedLock<true> lock(*SymbolsMutex);
+  // If we've already loaded this library, tell the caller.
+  if (!OpenedHandles->insert(handle).second) {
+    if (errMsg) *errMsg = "Library already loaded";
+    return DynamicLibrary();
+  }
+
+  return DynamicLibrary(handle);
+}
+
+void *DynamicLibrary::getAddressOfSymbol(const char *symbolName) {
+  if (!isValid())
+    return nullptr;
+  return dlsym(Data, symbolName);
+}
+
+#else
+
+using namespace llvm;
+using namespace llvm::sys;
+
+DynamicLibrary DynamicLibrary::getPermanentLibrary(const char *filename,
+                                                   std::string *errMsg) {
+  if (errMsg) *errMsg = "dlopen() not supported on this platform";
+  return DynamicLibrary();
+}
+
+void *DynamicLibrary::getAddressOfSymbol(const char *symbolName) {
+  return NULL;
+}
 
 #endif
 
-char DynamicLibrary::Invalid;
-
 namespace llvm {
-void *SearchForAddressOfSpecialSymbol(const char *SymbolName) {
-  return DoSearch(SymbolName); // DynamicLibrary.inc
-}
+void *SearchForAddressOfSpecialSymbol(const char* symbolName);
 }
 
-void DynamicLibrary::AddSymbol(StringRef SymbolName, void *SymbolValue) {
+void* DynamicLibrary::SearchForAddressOfSymbol(const char *symbolName) {
   SmartScopedLock<true> Lock(*SymbolsMutex);
-  (*ExplicitSymbols)[SymbolName] = SymbolValue;
-}
 
-DynamicLibrary DynamicLibrary::getPermanentLibrary(const char *FileName,
-                                                   std::string *Err) {
-  SmartScopedLock<true> Lock(*SymbolsMutex);
-  void *Handle = HandleSet::DLOpen(FileName, Err);
-  if (Handle != &Invalid)
-    OpenedHandles->AddLibrary(Handle, /*IsProcess*/ FileName == nullptr);
+  // First check symbols added via AddSymbol().
+  if (ExplicitSymbols.isConstructed()) {
+    StringMap<void *>::iterator i = ExplicitSymbols->find(symbolName);
 
-  return DynamicLibrary(Handle);
-}
-
-DynamicLibrary DynamicLibrary::addPermanentLibrary(void *Handle,
-                                                   std::string *Err) {
-  SmartScopedLock<true> Lock(*SymbolsMutex);
-  // If we've already loaded this library, tell the caller.
-  if (!OpenedHandles->AddLibrary(Handle, /*IsProcess*/false, /*CanClose*/false))
-    *Err = "Library already loaded";
-
-  return DynamicLibrary(Handle);
-}
-
-void *DynamicLibrary::getAddressOfSymbol(const char *SymbolName) {
-  if (!isValid())
-    return nullptr;
-  return HandleSet::DLSym(Data, SymbolName);
-}
-
-void *DynamicLibrary::SearchForAddressOfSymbol(const char *SymbolName) {
-  {
-    SmartScopedLock<true> Lock(*SymbolsMutex);
-
-    // First check symbols added via AddSymbol().
-    if (ExplicitSymbols.isConstructed()) {
-      StringMap<void *>::iterator i = ExplicitSymbols->find(SymbolName);
-
-      if (i != ExplicitSymbols->end())
-        return i->second;
-    }
-
-    // Now search the libraries.
-    if (OpenedHandles.isConstructed()) {
-      if (void *Ptr = OpenedHandles->Lookup(SymbolName))
-        return Ptr;
-    }
+    if (i != ExplicitSymbols->end())
+      return i->second;
   }
 
-  return llvm::SearchForAddressOfSpecialSymbol(SymbolName);
+#if defined(HAVE_DLFCN_H) && defined(HAVE_DLOPEN)
+  // Now search the libraries.
+  if (OpenedHandles.isConstructed()) {
+    for (DenseSet<void *>::iterator I = OpenedHandles->begin(),
+         E = OpenedHandles->end(); I != E; ++I) {
+      //lt_ptr ptr = lt_dlsym(*I, symbolName);
+      void *ptr = dlsym(*I, symbolName);
+      if (ptr) {
+        return ptr;
+      }
+    }
+  }
+#endif
+
+  if (void *Result = llvm::SearchForAddressOfSpecialSymbol(symbolName))
+    return Result;
+
+// This macro returns the address of a well-known, explicit symbol
+#define EXPLICIT_SYMBOL(SYM) \
+   if (!strcmp(symbolName, #SYM)) return &SYM
+
+// On linux we have a weird situation. The stderr/out/in symbols are both
+// macros and global variables because of standards requirements. So, we
+// boldly use the EXPLICIT_SYMBOL macro without checking for a #define first.
+#if defined(__linux__) and !defined(__ANDROID__)
+  {
+    EXPLICIT_SYMBOL(stderr);
+    EXPLICIT_SYMBOL(stdout);
+    EXPLICIT_SYMBOL(stdin);
+  }
+#else
+  // For everything else, we want to check to make sure the symbol isn't defined
+  // as a macro before using EXPLICIT_SYMBOL.
+  {
+#ifndef stdin
+    EXPLICIT_SYMBOL(stdin);
+#endif
+#ifndef stdout
+    EXPLICIT_SYMBOL(stdout);
+#endif
+#ifndef stderr
+    EXPLICIT_SYMBOL(stderr);
+#endif
+  }
+#endif
+#undef EXPLICIT_SYMBOL
+
+  return nullptr;
 }
 
+#endif // LLVM_ON_WIN32
+
 //===----------------------------------------------------------------------===//
 // C API.
 //===----------------------------------------------------------------------===//
 
-LLVMBool LLVMLoadLibraryPermanently(const char *Filename) {
+LLVMBool LLVMLoadLibraryPermanently(const char* Filename) {
   return llvm::sys::DynamicLibrary::LoadLibraryPermanently(Filename);
 }