diff --git a/llvm/lib/Transforms/Scalar/LoopDeletion.cpp b/llvm/lib/Transforms/Scalar/LoopDeletion.cpp
--- a/llvm/lib/Transforms/Scalar/LoopDeletion.cpp
+++ b/llvm/lib/Transforms/Scalar/LoopDeletion.cpp
@@ -151,14 +151,6 @@
   if (!BTC->isZero())
     return LoopDeletionResult::Unmodified;
 
-  // For non-outermost loops, the tricky case is that we can drop blocks
-  // out of both inner and outer loops at the same time.  This results in
-  // new exiting block for the outer loop appearing, and possibly needing
-  // an lcssa phi inserted.  (See loop_nest_lcssa test case in zero-btc.ll)
-  // TODO: We can handle a bunch of cases here without much work, revisit.
-  if (!L->isOutermost())
-    return LoopDeletionResult::Unmodified;
-
   breakLoopBackedge(L, DT, SE, LI, MSSA);
   return LoopDeletionResult::Deleted;
 }
diff --git a/llvm/lib/Transforms/Utils/LoopUtils.cpp b/llvm/lib/Transforms/Utils/LoopUtils.cpp
--- a/llvm/lib/Transforms/Utils/LoopUtils.cpp
+++ b/llvm/lib/Transforms/Utils/LoopUtils.cpp
@@ -761,13 +761,18 @@
   }
 }
 
+static Loop *getOutermostLoop(Loop *L) {
+  while (Loop *Parent = L->getParentLoop())
+    L = Parent;
+  return L;
+}
+
 void llvm::breakLoopBackedge(Loop *L, DominatorTree &DT, ScalarEvolution &SE,
                              LoopInfo &LI, MemorySSA *MSSA) {
-
-  assert(L->isOutermost() && "Can't yet preserve LCSSA for this case");
   auto *Latch = L->getLoopLatch();
   assert(Latch && "multiple latches not yet supported");
   auto *Header = L->getHeader();
+  Loop *OutermostLoop = getOutermostLoop(L);
 
   SE.forgetLoop(L);
 
@@ -790,6 +795,14 @@
   // Erase (and destroy) this loop instance.  Handles relinking sub-loops
   // and blocks within the loop as needed.
   LI.erase(L);
+
+  // If the loop we broke had a parent, then changeToUnreachable might have
+  // caused a block to be removed from the parent loop (see loop_nest_lcssa
+  // test case in zero-btc.ll for an example), thus changing the parent's
+  // exit blocks.  If that happened, we need to rebuild LCSSA on the outermost
+  // loop which might have a had a block removed.
+  if (OutermostLoop != L)
+    formLCSSARecursively(*OutermostLoop, DT, &LI, &SE);
 }
 
 
diff --git a/llvm/test/Transforms/IndVarSimplify/X86/pr45360.ll b/llvm/test/Transforms/IndVarSimplify/X86/pr45360.ll
--- a/llvm/test/Transforms/IndVarSimplify/X86/pr45360.ll
+++ b/llvm/test/Transforms/IndVarSimplify/X86/pr45360.ll
@@ -23,8 +23,8 @@
 ; CHECK-NEXT:    [[I6:%.*]] = load i32, i32* @a, align 4
 ; CHECK-NEXT:    [[I24:%.*]] = load i32, i32* @b, align 4
 ; CHECK-NEXT:    [[D_PROMOTED9:%.*]] = load i32, i32* @d, align 4
-; CHECK-NEXT:    br label [[BB1:%.*]]
-; CHECK:       bb1:
+; CHECK-NEXT:    br label [[BB13_PREHEADER:%.*]]
+; CHECK:       bb13.preheader:
 ; CHECK-NEXT:    [[I8_LCSSA10:%.*]] = phi i32 [ [[D_PROMOTED9]], [[BB:%.*]] ], [ [[I8:%.*]], [[BB19_PREHEADER:%.*]] ]
 ; CHECK-NEXT:    [[I8]] = and i32 [[I8_LCSSA10]], [[I6]]
 ; CHECK-NEXT:    [[I21:%.*]] = icmp eq i32 [[I8]], 0
@@ -33,7 +33,7 @@
 ; CHECK-NEXT:    [[I26:%.*]] = urem i32 [[I24]], [[I8]]
 ; CHECK-NEXT:    store i32 [[I26]], i32* @e, align 4
 ; CHECK-NEXT:    [[I30_NOT:%.*]] = icmp eq i32 [[I26]], 0
-; CHECK-NEXT:    br i1 [[I30_NOT]], label [[BB32_LOOPEXIT:%.*]], label [[BB1]]
+; CHECK-NEXT:    br i1 [[I30_NOT]], label [[BB32_LOOPEXIT:%.*]], label [[BB13_PREHEADER]]
 ; CHECK:       bb13.preheader.bb27.thread.split_crit_edge:
 ; CHECK-NEXT:    store i32 -1, i32* @f, align 4
 ; CHECK-NEXT:    store i32 0, i32* @d, align 4
diff --git a/llvm/test/Transforms/LoopDeletion/zero-btc.ll b/llvm/test/Transforms/LoopDeletion/zero-btc.ll
--- a/llvm/test/Transforms/LoopDeletion/zero-btc.ll
+++ b/llvm/test/Transforms/LoopDeletion/zero-btc.ll
@@ -302,7 +302,9 @@
 ; CHECK-NEXT:    br label [[INNER:%.*]]
 ; CHECK:       inner:
 ; CHECK-NEXT:    store i32 0, i32* @G, align 4
-; CHECK-NEXT:    br i1 false, label [[INNER]], label [[LATCH]]
+; CHECK-NEXT:    br i1 false, label [[INNER_INNER_CRIT_EDGE:%.*]], label [[LATCH]]
+; CHECK:       inner.inner_crit_edge:
+; CHECK-NEXT:    unreachable
 ; CHECK:       latch:
 ; CHECK-NEXT:    store i32 [[IV]], i32* @G, align 4
 ; CHECK-NEXT:    [[IV_INC]] = add i32 [[IV]], 1
@@ -346,11 +348,14 @@
 ; CHECK:       inner_header:
 ; CHECK-NEXT:    br i1 false, label [[INNER_LATCH:%.*]], label [[OUTER_LATCH:%.*]]
 ; CHECK:       inner_latch:
-; CHECK-NEXT:    br i1 false, label [[INNER_HEADER]], label [[LOOPEXIT:%.*]]
+; CHECK-NEXT:    [[DOTLCSSA:%.*]] = phi i32 [ [[TMP0]], [[INNER_HEADER]] ]
+; CHECK-NEXT:    br i1 false, label [[INNER_LATCH_INNER_HEADER_CRIT_EDGE:%.*]], label [[LOOPEXIT:%.*]]
+; CHECK:       inner_latch.inner_header_crit_edge:
+; CHECK-NEXT:    unreachable
 ; CHECK:       outer_latch:
 ; CHECK-NEXT:    br label [[OUTER_HEADER]]
 ; CHECK:       loopexit:
-; CHECK-NEXT:    [[DOTLCSSA32:%.*]] = phi i32 [ [[TMP0]], [[INNER_LATCH]] ]
+; CHECK-NEXT:    [[DOTLCSSA32:%.*]] = phi i32 [ [[DOTLCSSA]], [[INNER_LATCH]] ]
 ; CHECK-NEXT:    unreachable
 ;
 entry: