diff --git a/lib/Analysis/UninitializedValues.cpp b/lib/Analysis/UninitializedValues.cpp
index fbfa46c..1f97c58 100644
--- a/lib/Analysis/UninitializedValues.cpp
+++ b/lib/Analysis/UninitializedValues.cpp
@@ -116,6 +116,7 @@
 
   BVPair &getValueVectors(const CFGBlock *block, bool shouldLazyCreate);
 
+  void setAllScratchValues(Value V);
   void mergeIntoScratch(ValueVector const &source, bool isFirst);
   bool updateValueVectorWithScratch(const CFGBlock *block);
   bool updateValueVectors(const CFGBlock *block, const BVPair &newVals);
@@ -240,6 +241,11 @@
 }
 #endif
 
+void CFGBlockValues::setAllScratchValues(Value V) {
+  for (unsigned I = 0, E = scratch.size(); I != E; ++I)
+    scratch[I] = V;
+}
+
 void CFGBlockValues::mergeIntoScratch(ValueVector const &source,
                                       bool isFirst) {
   if (isFirst)
@@ -374,6 +380,7 @@
   void reportUse(const Expr *ex, const VarDecl *vd);
 
   void VisitBlockExpr(BlockExpr *be);
+  void VisitCallExpr(CallExpr *ce);
   void VisitDeclStmt(DeclStmt *ds);
   void VisitDeclRefExpr(DeclRefExpr *dr);
   void VisitUnaryOperator(UnaryOperator *uo);
@@ -576,6 +583,17 @@
   }
 }
 
+void TransferFunctions::VisitCallExpr(CallExpr *ce) {
+  // After a call to a function like setjmp or vfork, any variable which is
+  // initialized anywhere within this function may now be initialized. For now,
+  // just assume such a call initializes all variables.
+  // FIXME: Only mark variables as initialized if they have an initializer which
+  // is reachable from here.
+  Decl *Callee = ce->getCalleeDecl();
+  if (Callee && Callee->hasAttr<ReturnsTwiceAttr>())
+    vals.setAllScratchValues(Initialized);
+}
+
 void TransferFunctions::VisitDeclRefExpr(DeclRefExpr *dr) {
   // Record the last DeclRefExpr seen.  This is an lvalue computation.
   // We use this value to later detect if a variable "escapes" the analysis.