Index: llvm/trunk/lib/Transforms/Scalar/LoopUnrollPass.cpp
===================================================================
--- llvm/trunk/lib/Transforms/Scalar/LoopUnrollPass.cpp
+++ llvm/trunk/lib/Transforms/Scalar/LoopUnrollPass.cpp
@@ -1160,7 +1160,8 @@
 #endif
 
   // Unrolling can do several things to introduce new loops into a loop nest:
-  // - Partial unrolling clones child loops within the current loop.
+  // - Partial unrolling clones child loops within the current loop. If it
+  //   uses a remainder, then it can also create any number of sibling loops.
   // - Full unrolling clones child loops within the current loop but then
   //   removes the current loop making all of the children appear to be new
   //   sibling loops.
Index: llvm/trunk/lib/Transforms/Utils/LoopUnroll.cpp
===================================================================
--- llvm/trunk/lib/Transforms/Utils/LoopUnroll.cpp
+++ llvm/trunk/lib/Transforms/Utils/LoopUnroll.cpp
@@ -199,11 +199,14 @@
     assert(OriginalBB == OldLoop->getHeader() &&
            "Header should be first in RPO");
 
+    NewLoop = new Loop();
     Loop *NewLoopParent = NewLoops.lookup(OldLoop->getParentLoop());
-    assert(NewLoopParent &&
-           "Expected parent loop before sub-loop in RPO");
-    NewLoop = new Loop;
-    NewLoopParent->addChildLoop(NewLoop);
+
+    if (NewLoopParent)
+      NewLoopParent->addChildLoop(NewLoop);
+    else
+      LI->addTopLevelLoop(NewLoop);
+
     NewLoop->addBasicBlockToLoop(ClonedBB, *LI);
     return OldLoop;
   } else {
Index: llvm/trunk/lib/Transforms/Utils/LoopUnrollRuntime.cpp
===================================================================
--- llvm/trunk/lib/Transforms/Utils/LoopUnrollRuntime.cpp
+++ llvm/trunk/lib/Transforms/Utils/LoopUnrollRuntime.cpp
@@ -311,17 +311,22 @@
   }
 
   NewLoopsMap NewLoops;
-  NewLoops[L] = NewLoop;
+  if (NewLoop)
+    NewLoops[L] = NewLoop;
+  else if (ParentLoop)
+    NewLoops[L] = ParentLoop;
+
   // For each block in the original loop, create a new copy,
   // and update the value map with the newly created values.
   for (LoopBlocksDFS::RPOIterator BB = BlockBegin; BB != BlockEnd; ++BB) {
     BasicBlock *NewBB = CloneBasicBlock(*BB, VMap, "." + suffix, F);
     NewBlocks.push_back(NewBB);
-
-    if (NewLoop) {
+   
+    // If we're unrolling the outermost loop, there's no remainder loop,
+    // and this block isn't in a nested loop, then the new block is not
+    // in any loop. Otherwise, add it to loopinfo.
+    if (CreateRemainderLoop || LI->getLoopFor(*BB) != L || ParentLoop)
       addClonedBlockToLoopInfo(*BB, NewBB, LI, NewLoops);
-    } else if (ParentLoop)
-      ParentLoop->addBasicBlockToLoop(NewBB, *LI);
 
     VMap[*BB] = NewBB;
     if (Header == *BB) {
Index: llvm/trunk/test/Transforms/LoopUnroll/revisit.ll
===================================================================
--- llvm/trunk/test/Transforms/LoopUnroll/revisit.ll
+++ llvm/trunk/test/Transforms/LoopUnroll/revisit.ll
@@ -123,7 +123,7 @@
 ; CHECK: LoopUnrollPass on Loop at depth 2 containing: %l0.0
 ; CHECK-NOT: LoopUnrollPass
 ;
-; Partial unrolling occurs which introduces new child loops but not new sibling
+; Partial unrolling occurs which introduces both new child loops and new sibling
 ; loops. We only visit the child loops in a special mode, not by default.
 ; CHECK-CHILDREN: LoopUnrollPass on Loop at depth 3 containing: %l0.0.0<header>
 ; CHECK-CHILDREN-NOT: LoopUnrollPass
@@ -137,7 +137,13 @@
 ; When we revisit children, we also revisit the current loop.
 ; CHECK-CHILDREN: LoopUnrollPass on Loop at depth 2 containing: %l0.0<header>
 ; CHECK-CHILDREN-NOT: LoopUnrollPass
-
+;
+; Revisit the children of the outer loop that are part of the prologue.
+; 
+; CHECK: LoopUnrollPass on Loop at depth 2 containing: %l0.0.0.prol<header>
+; CHECK-NOT: LoopUnrollPass
+; CHECK: LoopUnrollPass on Loop at depth 2 containing: %l0.0.1.prol<header>
+; CHECK-NOT: LoopUnrollPass
 l0.latch:
   br label %l0
 ; CHECK: LoopUnrollPass on Loop at depth 1 containing: %l0<header>
Index: llvm/trunk/test/Transforms/LoopUnroll/runtime-li.ll
===================================================================
--- llvm/trunk/test/Transforms/LoopUnroll/runtime-li.ll
+++ llvm/trunk/test/Transforms/LoopUnroll/runtime-li.ll
@@ -0,0 +1,36 @@
+; RUN: opt -S -loop-unroll -unroll-runtime -unroll-count=2 -verify-loop-info -pass-remarks=loop-unroll < %s 2>&1 | FileCheck %s
+
+target datalayout = "e-m:e-i64:64-f80:128-n8:16:32:64-S128"
+target triple = "x86_64-unknown-linux-gnu"
+
+; Verify that runtime-unrolling a top-level loop that has nested loops does not
+; make the unroller produce invalid loop-info.
+; CHECK: remark: {{.*}}: unrolled loop by a factor of 2 with run-time trip count
+; CHECK: @widget
+; CHECK: ret void
+define void @widget(double* %arg, double* %arg1, double* %p, i64* %q1, i64* %q2) local_unnamed_addr {
+entry:
+  br label %header.outer
+
+header.outer:                                     ; preds = %latch.outer, %entry
+  %tmp = phi double* [ %tmp8, %latch.outer ], [ %arg, %entry ]
+  br label %header.inner
+
+header.inner:                                     ; preds = %latch.inner, %header.outer
+  br i1 undef, label %latch.inner, label %latch.outer
+
+latch.inner:                                      ; preds = %header.inner
+  %tmp5 = load i64, i64* %q1, align 8
+  store i64 %tmp5, i64* %q2, align 8
+  %tmp6 = icmp eq double* %p, %arg
+  br label %header.inner
+
+latch.outer:                                      ; preds = %header.inner
+  store double 0.0, double* %p, align 8
+  %tmp8 = getelementptr inbounds double, double* %tmp, i64 1
+  %tmp9 = icmp eq double* %tmp8, %arg1
+  br i1 %tmp9, label %exit, label %header.outer
+
+exit:                                             ; preds = %latch.outer
+  ret void
+}