diff --git a/lib/ExecutionEngine/JIT/JIT.cpp b/lib/ExecutionEngine/JIT/JIT.cpp
index 26afa54..9b5a176 100644
--- a/lib/ExecutionEngine/JIT/JIT.cpp
+++ b/lib/ExecutionEngine/JIT/JIT.cpp
@@ -366,6 +366,32 @@
   }    
 }
 
+/// materializeFunction - make sure the given function is fully read.  If the
+/// module is corrupt, this returns true and fills in the optional string with
+/// information about the problem.  If successful, this returns false.
+bool JIT::materializeFunction(Function *F, std::string *ErrInfo) {
+  // Read in the function if it exists in this Module.
+  if (F->hasNotBeenReadFromBitcode()) {
+    // Determine the module provider this function is provided by.
+    Module *M = F->getParent();
+    ModuleProvider *MP = 0;
+    for (unsigned i = 0, e = Modules.size(); i != e; ++i) {
+      if (Modules[i]->getModule() == M) {
+        MP = Modules[i];
+        break;
+      }
+    }
+    if (MP)
+      return MP->materializeFunction(F, ErrInfo);
+
+    if (ErrInfo)
+      *ErrInfo = "Function isn't in a module we know about!";
+    return true;
+  }
+  // Succeed if the function is already read.
+  return false;
+}
+
 /// run - Start execution with the specified function and arguments.
 ///
 GenericValue JIT::runFunction(Function *F,
@@ -607,6 +633,9 @@
     Function *PF = jitstate->getPendingFunctions(locked).back();
     jitstate->getPendingFunctions(locked).pop_back();
 
+    assert(!PF->hasAvailableExternallyLinkage() &&
+           "Externally-defined function should not be in pending list.");
+
     // JIT the function
     isAlreadyCodeGenerating = true;
     jitstate->getPM(locked).run(*PF);
@@ -627,36 +656,19 @@
     return Addr;   // Check if function already code gen'd
 
   MutexGuard locked(lock);
-  
-  // Now that this thread owns the lock, check if another thread has already
-  // code gen'd the function.
-  if (void *Addr = getPointerToGlobalIfAvailable(F))
-    return Addr;  
 
-  // Make sure we read in the function if it exists in this Module.
-  if (F->hasNotBeenReadFromBitcode()) {
-    // Determine the module provider this function is provided by.
-    Module *M = F->getParent();
-    ModuleProvider *MP = 0;
-    for (unsigned i = 0, e = Modules.size(); i != e; ++i) {
-      if (Modules[i]->getModule() == M) {
-        MP = Modules[i];
-        break;
-      }
-    }
-    assert(MP && "Function isn't in a module we know about!");
-    
-    std::string ErrorMsg;
-    if (MP->materializeFunction(F, &ErrorMsg)) {
-      llvm_report_error("Error reading function '" + F->getName()+
-                        "' from bitcode file: " + ErrorMsg);
-    }
-
-    // Now retry to get the address.
-    if (void *Addr = getPointerToGlobalIfAvailable(F))
-      return Addr;
+  // Now that this thread owns the lock, make sure we read in the function if it
+  // exists in this Module.
+  std::string ErrorMsg;
+  if (materializeFunction(F, &ErrorMsg)) {
+    llvm_report_error("Error reading function '" + F->getName()+
+                      "' from bitcode file: " + ErrorMsg);
   }
 
+  // ... and check if another thread has already code gen'd the function.
+  if (void *Addr = getPointerToGlobalIfAvailable(F))
+    return Addr;
+
   if (F->isDeclaration() || F->hasAvailableExternallyLinkage()) {
     bool AbortOnFailure = !F->hasExternalWeakLinkage();
     void *Addr = getPointerToNamedFunction(F->getName(), AbortOnFailure);
diff --git a/lib/ExecutionEngine/JIT/JIT.h b/lib/ExecutionEngine/JIT/JIT.h
index f165bd6..b6f74ff 100644
--- a/lib/ExecutionEngine/JIT/JIT.h
+++ b/lib/ExecutionEngine/JIT/JIT.h
@@ -104,6 +104,12 @@
   /// the underlying module.
   virtual void deleteModuleProvider(ModuleProvider *P,std::string *ErrInfo = 0);
 
+  /// materializeFunction - make sure the given function is fully read.  If the
+  /// module is corrupt, this returns true and fills in the optional string with
+  /// information about the problem.  If successful, this returns false.
+  ///
+  bool materializeFunction(Function *F, std::string *ErrInfo = 0);
+
   /// runFunction - Start execution with the specified function and arguments.
   ///
   virtual GenericValue runFunction(Function *F,
diff --git a/lib/ExecutionEngine/JIT/JITEmitter.cpp b/lib/ExecutionEngine/JIT/JITEmitter.cpp
index a670772..e3523ff 100644
--- a/lib/ExecutionEngine/JIT/JITEmitter.cpp
+++ b/lib/ExecutionEngine/JIT/JITEmitter.cpp
@@ -517,9 +517,15 @@
   void *Actual = TheJIT->isCompilingLazily()
     ? (void *)(intptr_t)LazyResolverFn : (void *)0;
 
+  // TODO: Delete this when PR5737 is fixed.
+  std::string ErrorMsg;
+  if (TheJIT->materializeFunction(F, &ErrorMsg)) {
+    llvm_report_error("Error reading function '" + F->getName()+
+                      "' from bitcode file: " + ErrorMsg);
+  }
   // If this is an external declaration, attempt to resolve the address now
   // to place in the stub.
-  if (F->isDeclaration() && !F->hasNotBeenReadFromBitcode()) {
+  if (F->isDeclaration() || F->hasAvailableExternallyLinkage()) {
     Actual = TheJIT->getPointerToFunction(F);
 
     // If we resolved the symbol to a null address (eg. a weak external)
@@ -552,7 +558,7 @@
   // exist yet, add it to the JIT's work list so that we can fill in the stub
   // address later.
   if (!Actual && !TheJIT->isCompilingLazily())
-    if (!F->isDeclaration() || F->hasNotBeenReadFromBitcode())
+    if (!F->isDeclaration() && !F->hasAvailableExternallyLinkage())
       TheJIT->addPendingFunction(F);
 
   return Stub;
@@ -755,9 +761,16 @@
     void *ResultPtr = TheJIT->getPointerToGlobalIfAvailable(F);
     if (ResultPtr) return ResultPtr;
 
+    // TODO: Delete this when PR5737 is fixed.
+    std::string ErrorMsg;
+    if (TheJIT->materializeFunction(F, &ErrorMsg)) {
+      llvm_report_error("Error reading function '" + F->getName()+
+                        "' from bitcode file: " + ErrorMsg);
+    }
+
     // If this is an external function pointer, we can force the JIT to
     // 'compile' it, which really just adds it to the map.
-    if (F->isDeclaration() && !F->hasNotBeenReadFromBitcode())
+    if (F->isDeclaration() || F->hasAvailableExternallyLinkage())
       return TheJIT->getPointerToFunction(F);
   }
 
@@ -1562,6 +1575,7 @@
   JITEmitter *JE = cast<JITEmitter>(getCodeEmitter());
   void *Stub = JE->getJITResolver().getLazyFunctionStub(F);
   void *Addr = getPointerToGlobalIfAvailable(F);
+  assert(Addr != Stub && "Function must have non-stub address to be updated.");
 
   // Tell the target jit info to rewrite the stub at the specified address,
   // rather than creating a new one.