diff --git a/lib/Transforms/IPO/AddReadAttrs.cpp b/lib/Transforms/IPO/AddReadAttrs.cpp
index 5460a5bde7b..2835d5e9f36 100644
--- a/lib/Transforms/IPO/AddReadAttrs.cpp
+++ b/lib/Transforms/IPO/AddReadAttrs.cpp
@@ -17,6 +17,7 @@
 #define DEBUG_TYPE "addreadattrs"
 #include "llvm/Transforms/IPO.h"
 #include "llvm/CallGraphSCCPass.h"
+#include "llvm/GlobalVariable.h"
 #include "llvm/Instructions.h"
 #include "llvm/Analysis/CallGraph.h"
 #include "llvm/ADT/SmallPtrSet.h"
@@ -40,6 +41,8 @@ namespace {
       AU.setPreservesCFG();
       CallGraphSCCPass::getAnalysisUsage(AU);
     }
+
+    bool PointsToLocalMemory(Value *V);
   };
 }
 
@@ -50,6 +53,20 @@ X("addreadattrs", "Mark functions readnone/readonly");
 Pass *llvm::createAddReadAttrsPass() { return new AddReadAttrs(); }
 
 
+/// PointsToLocalMemory - Returns whether the given pointer value points to
+/// memory that is local to the function.  Global constants are considered
+/// local to all functions.
+bool AddReadAttrs::PointsToLocalMemory(Value *V) {
+  V = V->getUnderlyingObject();
+  // An alloca instruction defines local memory.
+  if (isa<AllocaInst>(V))
+    return true;
+  // A global constant counts as local memory for our purposes.
+  if (GlobalVariable *GV = dyn_cast<GlobalVariable>(V))
+    return GV->isConstant();
+  return false;
+}
+
 bool AddReadAttrs::runOnSCC(const std::vector<CallGraphNode *> &SCC) {
   SmallPtrSet<CallGraphNode *, 8> SCCNodes;
   CallGraph &CG = getAnalysis<CallGraph>();
@@ -96,14 +113,12 @@ bool AddReadAttrs::runOnSCC(const std::vector<CallGraphNode *> &SCC) {
         if (SCCNodes.count(CG[CS.getCalledFunction()]))
           continue;
       } else if (LoadInst *LI = dyn_cast<LoadInst>(I)) {
-        Value *Target = LI->getPointerOperand()->getUnderlyingObject();
         // Ignore loads from local memory.
-        if (isa<AllocaInst>(Target))
+        if (PointsToLocalMemory(LI->getPointerOperand()))
           continue;
       } else if (StoreInst *SI = dyn_cast<StoreInst>(I)) {
-        Value *Target = SI->getPointerOperand()->getUnderlyingObject();
         // Ignore stores to local memory.
-        if (isa<AllocaInst>(Target))
+        if (PointsToLocalMemory(SI->getPointerOperand()))
           continue;
       }
 
diff --git a/test/Transforms/AddReadAttrs/2008-12-29-Constant.ll b/test/Transforms/AddReadAttrs/2008-12-29-Constant.ll
new file mode 100644
index 00000000000..fe038c1be9a
--- /dev/null
+++ b/test/Transforms/AddReadAttrs/2008-12-29-Constant.ll
@@ -0,0 +1,8 @@
+; RUN: llvm-as < %s | opt -addreadattrs | llvm-dis | grep readnone
+
+@s = external constant i8		; <i8*> [#uses=1]
+
+define i8 @f() {
+	%tmp = load i8* @s		; <i8> [#uses=1]
+	ret i8 %tmp
+}