diff --git a/lib/Transforms/Scalar/LoopRotation.cpp b/lib/Transforms/Scalar/LoopRotation.cpp
index 65acc1d9257..a0d07726fe8 100644
--- a/lib/Transforms/Scalar/LoopRotation.cpp
+++ b/lib/Transforms/Scalar/LoopRotation.cpp
@@ -143,11 +143,11 @@ bool LoopRotate::rotateLoop(Loop *Lp, LPPassManager &LPM) {
   // FIXME: Use common api to estimate size.
   for (BasicBlock::const_iterator OI = OrigHeader->begin(), 
          OE = OrigHeader->end(); OI != OE; ++OI) {
-      if (isa<PHINode>(OI)) 
-        continue;           // PHI nodes don't count.
-      if (isa<DbgInfoIntrinsic>(OI))
-        continue;  // Debug intrinsics don't count as size.
-      ++Size;
+    if (isa<PHINode>(OI)) 
+      continue;           // PHI nodes don't count.
+    if (isa<DbgInfoIntrinsic>(OI))
+      continue;  // Debug intrinsics don't count as size.
+    ++Size;
   }
 
   if (Size > MAX_HEADER_SIZE)
@@ -187,13 +187,30 @@ bool LoopRotate::rotateLoop(Loop *Lp, LPPassManager &LPM) {
   for (; PHINode *PN = dyn_cast<PHINode>(I); ++I)
     ValueMap[PN] = PN->getIncomingValue(PN->getBasicBlockIndex(OrigPreHeader));
 
-  // For the rest of the instructions, create a clone in the OldPreHeader.
+  // For the rest of the instructions, either hoist to the OrigPreheader if
+  // possible or create a clone in the OldPreHeader if not.
   TerminatorInst *LoopEntryBranch = OrigPreHeader->getTerminator();
-  for (; I != E; ++I) {
-    Instruction *C = I->clone();
-    C->setName(I->getName());
+  while (I != E) {
+    Instruction *Inst = I++;
+    
+    // If the instruction's operands are invariant and it doesn't read or write
+    // memory, then it is safe to hoist.  Doing this doesn't change the order of
+    // execution in the preheader, but does prevent the instruction from
+    // executing in each iteration of the loop.  This means it is safe to hoist
+    // something that might trap, but isn't safe to hoist something that reads
+    // memory (without proving that the loop doesn't write).
+    if (L->hasLoopInvariantOperands(Inst) &&
+        !Inst->mayReadFromMemory() && !Inst->mayWriteToMemory() &&
+        !isa<TerminatorInst>(Inst)) {
+      Inst->moveBefore(LoopEntryBranch);
+      continue;
+    }
+    
+    // Otherwise, create a duplicate of the instruction.
+    Instruction *C = Inst->clone();
+    C->setName(Inst->getName());
     C->insertBefore(LoopEntryBranch);
-    ValueMap[I] = C;
+    ValueMap[Inst] = C;
   }
 
   // Along with all the other instructions, we just cloned OrigHeader's
diff --git a/test/Transforms/LoopRotate/basic.ll b/test/Transforms/LoopRotate/basic.ll
new file mode 100644
index 00000000000..b7bcb21d56f
--- /dev/null
+++ b/test/Transforms/LoopRotate/basic.ll
@@ -0,0 +1,35 @@
+; RUN: opt -S -loop-rotate %s | FileCheck %s
+target datalayout = "e-p:64:64:64-i1:8:8-i8:8:8-i16:16:16-i32:32:32-i64:64:64-f32:32:32-f64:64:64-v64:64:64-v128:128:128-a0:0:64-s0:64:64-f80:128:128-n8:16:32:64"
+target triple = "x86_64-apple-darwin10.0.0"
+
+; PR5319 - The "arrayidx" gep should be hoisted, not duplicated.  We should
+; end up with one phi node.
+define void @test1() nounwind ssp {
+; CHECK: @test1
+entry:
+  %array = alloca [20 x i32], align 16
+  br label %for.cond
+
+for.cond:                                         ; preds = %for.body, %entry
+  %i.0 = phi i32 [ 0, %entry ], [ %inc, %for.body ]
+  %cmp = icmp slt i32 %i.0, 100
+  %arrayidx = getelementptr inbounds [20 x i32]* %array, i64 0, i64 0
+  br i1 %cmp, label %for.body, label %for.end
+
+; CHECK: for.body:
+; CHECK-NEXT: phi i32 [ 0
+; CHECK-NEXT: store i32 0
+
+for.body:                                         ; preds = %for.cond
+  store i32 0, i32* %arrayidx, align 16
+  %inc = add nsw i32 %i.0, 1
+  br label %for.cond
+
+for.end:                                          ; preds = %for.cond
+  %arrayidx.lcssa = phi i32* [ %arrayidx, %for.cond ]
+  call void @g(i32* %arrayidx.lcssa) nounwind
+  ret void
+}
+
+declare void @g(i32*)
+