Index: lib/Transforms/Utils/LoopRotationUtils.cpp
===================================================================
--- lib/Transforms/Utils/LoopRotationUtils.cpp
+++ lib/Transforms/Utils/LoopRotationUtils.cpp
@@ -259,9 +259,10 @@
     return false;
 
   // Anything ScalarEvolution may know about this loop or the PHI nodes
-  // in its header will soon be invalidated.
+  // in its header will soon be invalidated, and it can also affect its parent
+  // loops as well.
   if (SE)
-    SE->forgetLoop(L);
+    SE->forgetTopmostLoop(L);
 
   DEBUG(dbgs() << "LoopRotation: rotating "; L->dump());
 
@@ -476,6 +477,12 @@
 
   DEBUG(dbgs() << "LoopRotation: into "; L->dump());
 
+#ifndef NDEBUG
+  // Make sure that after all our transforms SE is correct.
+  if (SE)
+    SE->verify();
+#endif
+
   ++NumRotated;
   return true;
 }
Index: test/Transforms/LoopRotate/pr37205.ll
===================================================================
--- test/Transforms/LoopRotate/pr37205.ll
+++ test/Transforms/LoopRotate/pr37205.ll
@@ -0,0 +1,116 @@
+; NOTE: Assertions have been autogenerated by utils/update_test_checks.py
+; RUN: opt -S -indvars -verify -loop-rotate -loop-idiom < %s | FileCheck %s
+target triple = "x86_64-unknown-linux-gnu"
+
+; Verify that we invalidate SCEV properly.
+
+define void @test_01() {
+; CHECK-LABEL: @test_01(
+; CHECK-NEXT:  entry:
+; CHECK-NEXT:    br label [[LBL1:%.*]]
+; CHECK:       lbl1:
+; CHECK-NEXT:    br label [[FOR_COND:%.*]]
+; CHECK:       for.cond:
+; CHECK-NEXT:    br i1 false, label [[FOR_BODY3_LR_PH:%.*]], label [[FOR_COND_FOR_END5_CRIT_EDGE:%.*]]
+; CHECK:       for.body3.lr.ph:
+; CHECK-NEXT:    br label [[FOR_BODY3:%.*]]
+; CHECK:       for.cond1:
+; CHECK-NEXT:    br i1 false, label [[FOR_BODY3]], label [[FOR_COND1_FOR_END5_CRIT_EDGE:%.*]]
+; CHECK:       for.body3:
+; CHECK-NEXT:    br i1 false, label [[IF_THEN:%.*]], label [[FOR_COND1:%.*]]
+; CHECK:       if.then:
+; CHECK-NEXT:    br label [[LBL1]]
+; CHECK:       for.cond.for.end5_crit_edge:
+; CHECK-NEXT:    br label [[FOR_END5:%.*]]
+; CHECK:       for.cond1.for.end5_crit_edge:
+; CHECK-NEXT:    br label [[FOR_END5]]
+; CHECK:       for.end5:
+; CHECK-NEXT:    ret void
+;
+entry:
+  br label %lbl1
+
+lbl1:                                             ; preds = %if.then, %entry
+  br label %for.cond
+
+for.cond:                                         ; preds = %lbl1
+  br label %for.cond1
+
+for.cond1:                                        ; preds = %if.end, %for.cond
+  br i1 false, label %for.body3, label %for.end5
+
+for.body3:                                        ; preds = %for.cond1
+  br i1 false, label %if.then, label %if.end
+
+if.then:                                          ; preds = %for.body3
+  br label %lbl1
+
+if.end:                                           ; preds = %for.body3
+  br label %for.cond1
+
+for.end5:                                         ; preds = %for.cond1
+  ret void
+}
+
+define void @test_02() {
+; CHECK-LABEL: @test_02(
+; CHECK-NEXT:  entry:
+; CHECK-NEXT:    br label [[LBL1:%.*]]
+; CHECK:       lbl1:
+; CHECK-NEXT:    br label [[FOR_COND:%.*]]
+; CHECK:       for.cond:
+; CHECK-NEXT:    br i1 false, label [[IF_THEN:%.*]], label [[IF_END7:%.*]]
+; CHECK:       if.then:
+; CHECK-NEXT:    br i1 false, label [[FOR_BODY_LR_PH:%.*]], label [[IF_THEN_FOR_END6_CRIT_EDGE:%.*]]
+; CHECK:       for.body.lr.ph:
+; CHECK-NEXT:    br label [[FOR_BODY:%.*]]
+; CHECK:       for.body:
+; CHECK-NEXT:    br i1 false, label [[IF_THEN3:%.*]], label [[IF_END:%.*]]
+; CHECK:       if.then3:
+; CHECK-NEXT:    br label [[LBL1]]
+; CHECK:       if.end:
+; CHECK-NEXT:    br label [[FOR_COND4:%.*]]
+; CHECK:       for.cond4:
+; CHECK-NEXT:    br i1 false, label [[FOR_BODY]], label [[FOR_COND1_FOR_END6_CRIT_EDGE:%.*]]
+; CHECK:       if.then.for.end6_crit_edge:
+; CHECK-NEXT:    br label [[FOR_END6:%.*]]
+; CHECK:       for.cond1.for.end6_crit_edge:
+; CHECK-NEXT:    br label [[FOR_END6]]
+; CHECK:       for.end6:
+; CHECK-NEXT:    ret void
+; CHECK:       if.end7:
+; CHECK-NEXT:    unreachable
+;
+entry:
+  br label %lbl1
+
+lbl1:                                             ; preds = %if.then3, %entry
+  br label %for.cond
+
+for.cond:                                         ; preds = %lbl1
+  br i1 false, label %if.then, label %if.end7
+
+if.then:                                          ; preds = %for.cond
+  br label %for.cond1
+
+for.cond1:                                        ; preds = %for.cond4, %if.then
+  br i1 undef, label %for.body, label %for.end6
+
+for.body:                                         ; preds = %for.cond1
+  br i1 false, label %if.then3, label %if.end
+
+if.then3:                                         ; preds = %for.body
+  br label %lbl1
+
+if.end:                                           ; preds = %for.body
+  br label %for.cond4
+
+for.cond4:                                        ; preds = %if.end
+  br label %for.cond1
+
+for.end6:                                         ; preds = %for.cond1
+  ret void
+
+if.end7:                                          ; preds = %for.cond
+  unreachable
+}