diff --git a/llvm/lib/CodeGen/SjLjEHPrepare.cpp b/llvm/lib/CodeGen/SjLjEHPrepare.cpp
index 17a3a84..539bbb6 100644
--- a/llvm/lib/CodeGen/SjLjEHPrepare.cpp
+++ b/llvm/lib/CodeGen/SjLjEHPrepare.cpp
@@ -64,7 +64,6 @@
 
 private:
   bool setupEntryBlockAndCallSites(Function &F);
-  bool undoSwiftErrorSelect(Function &F);
   void substituteLPadValues(LandingPadInst *LPI, Value *ExnVal, Value *SelVal);
   Value *setupFunctionContext(Function &F, ArrayRef<LandingPadInst *> LPads);
   void lowerIncomingArguments(Function &F);
@@ -233,6 +232,13 @@
   assert(AfterAllocaInsPt != F.front().end());
 
   for (auto &AI : F.args()) {
+    // Swift error really is a register that we model as memory -- instruction
+    // selection will perform mem-to-reg for us and spill/reload appropriately
+    // around calls that clobber it. There is no need to spill this
+    // value to the stack and doing so would not be allowed.
+    if (AI.isSwiftError())
+      continue;
+
     Type *Ty = AI.getType();
 
     // Use 'select i8 true, %arg, undef' to simulate a 'no-op' instruction.
@@ -462,25 +468,6 @@
   return true;
 }
 
-bool SjLjEHPrepare::undoSwiftErrorSelect(Function &F) {
-  // We have inserted dummy copies 'select true, arg, undef' in the entry block
-  // for arguments to simplify this pass.
-  // swifterror arguments cannot be used in this way. Undo the select for the
-  // swifterror argument.
-  for (auto &AI : F.args()) {
-    if (AI.isSwiftError()) {
-      assert(AI.hasOneUse() && "Must have converted the argument to a select");
-      auto *Select = dyn_cast<SelectInst>(AI.use_begin()->getUser());
-      assert(Select && "There must be single select user");
-      auto *OrigSwiftError = cast<Argument>(Select->getTrueValue());
-      Select->replaceAllUsesWith(OrigSwiftError);
-      Select->eraseFromParent();
-      return true;
-    }
-  }
-  return false;
-}
-
 bool SjLjEHPrepare::runOnFunction(Function &F) {
   Module &M = *F.getParent();
   RegisterFn = M.getOrInsertFunction(
@@ -499,7 +486,5 @@
   FuncCtxFn = Intrinsic::getDeclaration(&M, Intrinsic::eh_sjlj_functioncontext);
 
   bool Res = setupEntryBlockAndCallSites(F);
-  if (Res)
-    Res |= undoSwiftErrorSelect(F);
   return Res;
 }