Index: include/llvm/LTO/LTOCodeGenerator.h
===================================================================
--- include/llvm/LTO/LTOCodeGenerator.h
+++ include/llvm/LTO/LTOCodeGenerator.h
@@ -39,6 +39,7 @@
 #include "llvm/ADT/ArrayRef.h"
 #include "llvm/ADT/SmallPtrSet.h"
 #include "llvm/ADT/StringMap.h"
+#include "llvm/IR/GlobalValue.h"
 #include "llvm/Target/TargetMachine.h"
 #include "llvm/Target/TargetOptions.h"
 #include <string>
@@ -47,7 +48,6 @@
 namespace llvm {
   class LLVMContext;
   class DiagnosticInfo;
-  class GlobalValue;
   class Linker;
   class Mangler;
   class MemoryBuffer;
@@ -154,6 +154,7 @@
   void initializeLTOPasses();
 
   bool compileOptimizedToFile(const char **Name);
+  void restoreLinkageForExternals();
   void applyScopeRestrictions();
   void applyRestriction(GlobalValue &GV, ArrayRef<StringRef> Libcalls,
                         std::vector<const char *> &MustPreserveList,
@@ -178,6 +179,7 @@
   Reloc::Model RelocModel = Reloc::Default;
   StringSet MustPreserveSymbols;
   StringSet AsmUndefinedRefs;
+  StringMap<GlobalValue::LinkageTypes> ExternalSymbols;
   std::vector<std::string> CodegenOptions;
   std::string FeatureStr;
   std::string MCpu;
Index: lib/LTO/LTOCodeGenerator.cpp
===================================================================
--- lib/LTO/LTOCodeGenerator.cpp
+++ lib/LTO/LTOCodeGenerator.cpp
@@ -56,6 +56,10 @@
 #include <system_error>
 using namespace llvm;
 
+static cl::opt<bool>
+RestoreExternals("restore-globals", cl::Hidden, cl::init(false),
+                 cl::desc("Restore original linkage of internalized globals"));
+
 const char* LTOCodeGenerator::getVersionString() {
 #ifdef LLVM_VERSION_INFO
   return PACKAGE_NAME " version " PACKAGE_VERSION ", " LLVM_VERSION_INFO;
@@ -347,6 +351,12 @@
   if (isa<Function>(GV) &&
       std::binary_search(Libcalls.begin(), Libcalls.end(), GV.getName()))
     AsmUsed.insert(&GV);
+
+  // Record the linkage type of non-local symbols so they can be restored prior
+  // to module splitting.
+  if (RestoreExternals && !GV.hasAvailableExternallyLinkage() &&
+      !GV.hasLocalLinkage() && GV.hasName())
+    ExternalSymbols.insert(std::make_pair(GV.getName(), GV.getLinkage()));
 }
 
 static void findUsedValues(GlobalVariable *LLVMUsed,
@@ -454,6 +464,35 @@
   ScopeRestrictionsDone = true;
 }
 
+/// Restore original linkage for symbols that may have been internalized
+void LTOCodeGenerator::restoreLinkageForExternals() {
+  if (!ShouldInternalize || !RestoreExternals)
+    return;
+
+  assert(ScopeRestrictionsDone &&
+         "Cannot externalize without internalization!");
+
+  if (ExternalSymbols.empty())
+    return;
+
+  auto externalize = [this](GlobalValue &GV) {
+    if (!GV.hasLocalLinkage() || !GV.hasName())
+      return;
+
+    auto I = ExternalSymbols.find(GV.getName());
+    if (I == ExternalSymbols.end())
+      return;
+
+    GV.setLinkage(I->second);
+  };
+
+  std::for_each(MergedModule->begin(), MergedModule->end(), externalize);
+  std::for_each(MergedModule->global_begin(), MergedModule->global_end(),
+                externalize);
+  std::for_each(MergedModule->alias_begin(), MergedModule->alias_end(),
+                externalize);
+}
+
 /// Optimize merged modules using various IPO passes
 bool LTOCodeGenerator::optimize(bool DisableVerify, bool DisableInline,
                                 bool DisableGVNLoadPRE,
@@ -504,6 +543,10 @@
   preCodeGenPasses.add(createObjCARCContractPass());
   preCodeGenPasses.run(*MergedModule);
 
+  // Re-externalize globals that may have been internalized to increase scope
+  // for splitting
+  restoreLinkageForExternals();
+
   // Do code generation. We need to preserve the module in case the client calls
   // writeMergedModules() after compilation, but we only need to allow this at
   // parallelism level 1. This is achieved by having splitCodeGen return the
Index: test/LTO/X86/restore-externals.ll
===================================================================
--- /dev/null
+++ test/LTO/X86/restore-externals.ll
@@ -0,0 +1,23 @@
+; Check that "internalizedfn" is re-externalized prior to CodeGen
+;
+; RUN: llvm-as < %s > %t1
+; RUN: llvm-lto -exported-symbol=preservedfn -restore-globals -filetype=asm -o - %t1 | FileCheck %s
+;
+; CHECK: .globl internalizedfn
+
+target triple = "x86_64-unknown-linux-gnu"
+
+declare void @f()
+
+define void @internalizedfn() noinline {
+entry:
+  call void @f()
+  ret void
+}
+
+define void @preservedfn() {
+entry:
+  call void @internalizedfn()
+  ret void
+}
+