diff --git a/llvm/lib/Transforms/Scalar/SimpleLoopUnswitch.cpp b/llvm/lib/Transforms/Scalar/SimpleLoopUnswitch.cpp
--- a/llvm/lib/Transforms/Scalar/SimpleLoopUnswitch.cpp
+++ b/llvm/lib/Transforms/Scalar/SimpleLoopUnswitch.cpp
@@ -331,6 +331,18 @@
   }
 }
 
+// Return the top-most loop containing ExitBB and having ExitBB as exiting block
+// or the loop containing ExitBB, if there is no parent loop containing ExitBB
+// as exiting block.
+static Loop *getTopMostExitingLoop(BasicBlock *ExitBB, LoopInfo &LI) {
+  Loop *TopMost = LI.getLoopFor(ExitBB);
+  Loop *Current = TopMost;
+  while ((Current = Current->getParentLoop()))
+    if (Current->isLoopExiting(ExitBB))
+      TopMost = Current;
+  return TopMost;
+}
+
 /// Unswitch a trivial branch if the condition is loop invariant.
 ///
 /// This routine should only be called when loop code leading to the branch has
@@ -415,9 +427,10 @@
   });
 
   // If we have scalar evolutions, we need to invalidate them including this
-  // loop and the loop containing the exit block.
+  // loop, the loop containing the exit block and the topmost parent loop
+  // exiting via LoopExitBB.
   if (SE) {
-    if (Loop *ExitL = LI.getLoopFor(LoopExitBB))
+    if (Loop *ExitL = getTopMostExitingLoop(LoopExitBB, LI))
       SE->forgetLoop(ExitL);
     else
       // Forget the entire nest as this exits the entire nest.
diff --git a/llvm/test/Transforms/SimpleLoopUnswitch/preserve-scev-exiting-multiple-loops.ll b/llvm/test/Transforms/SimpleLoopUnswitch/preserve-scev-exiting-multiple-loops.ll
new file mode 100644
--- /dev/null
+++ b/llvm/test/Transforms/SimpleLoopUnswitch/preserve-scev-exiting-multiple-loops.ll
@@ -0,0 +1,63 @@
+; NOTE: Assertions have been autogenerated by utils/update_test_checks.py
+
+; We run -indvars before -simple-loop-unswitch to compute SCEV exit counts before
+; running -simple-loop-unswitch.
+; RUN:  opt -indvars -simple-loop-unswitch -S %s -verify-scev | FileCheck %s
+
+; Test for PR43972.
+
+; We have a 3 nested loops (l1 <- l2 <- l3). %for.cond.5 is the exit block of
+; l3 and the loop for it is l2. But it is also the exiting block of l1. That
+; means we have to invalidate l1 to preserve SCEV.
+
+define void @f() {
+; CHECK-LABEL: @f(
+; CHECK-NEXT:  entry:
+; CHECK-NEXT:    [[LNOT:%.*]] = xor i1 undef, true
+; CHECK-NEXT:    br label [[FOR_COND:%.*]]
+; CHECK:       for.cond.loopexit:
+; CHECK-NEXT:    br label [[FOR_COND]]
+; CHECK:       for.cond:
+; CHECK-NEXT:    br label [[FOR_BODY:%.*]]
+; CHECK:       for.cond1:
+; CHECK-NEXT:    br i1 true, label [[FOR_BODY]], label [[FOR_COND_LOOPEXIT:%.*]]
+; CHECK:       for.body:
+; CHECK-NEXT:    br i1 [[LNOT]], label [[FOR_BODY_SPLIT:%.*]], label [[FOR_COND5_SPLIT:%.*]]
+; CHECK:       for.body.split:
+; CHECK-NEXT:    br label [[LAND_RHS:%.*]]
+; CHECK:       for.cond2:
+; CHECK-NEXT:    br i1 true, label [[LAND_RHS]], label [[FOR_COND5:%.*]]
+; CHECK:       land.rhs:
+; CHECK-NEXT:    br label [[FOR_COND2:%.*]]
+; CHECK:       for.cond5:
+; CHECK-NEXT:    br label [[FOR_COND5_SPLIT]]
+; CHECK:       for.cond5.split:
+; CHECK-NEXT:    br i1 true, label [[FOR_BODY7:%.*]], label [[FOR_COND1:%.*]]
+; CHECK:       for.body7:
+; CHECK-NEXT:    ret void
+;
+entry:
+  %lnot = xor i1 undef, true
+  br label %for.cond
+
+for.cond:                                         ; preds = %for.cond1, %entry
+  br label %for.body
+
+for.cond1:                                        ; preds = %for.cond5
+  br i1 true, label %for.body, label %for.cond
+
+for.body:                                         ; preds = %for.cond1, %for.cond
+  br label %land.rhs
+
+for.cond2:                                        ; preds = %land.rhs
+  br i1 true, label %land.rhs, label %for.cond5
+
+land.rhs:                                         ; preds = %for.cond2, %for.body
+  br i1 %lnot, label %for.cond2, label %for.cond5
+
+for.cond5:                                        ; preds = %land.rhs, %for.cond2
+  br i1 true, label %for.body7, label %for.cond1
+
+for.body7:                                        ; preds = %for.cond5
+  ret void
+}