Index: llvm/lib/Analysis/ScalarEvolutionExpander.cpp
===================================================================
--- llvm/lib/Analysis/ScalarEvolutionExpander.cpp
+++ llvm/lib/Analysis/ScalarEvolutionExpander.cpp
@@ -1733,35 +1733,36 @@
   // as far out in the loop nest as possible.
   Instruction *InsertPt = &*Builder.GetInsertPoint();
   for (Loop *L = SE.LI.getLoopFor(Builder.GetInsertBlock());;
-       L = L->getParentLoop())
+       L = L->getParentLoop()) {
+    // We can move insertion point only if there is no div or rem operations
+    // otherwise we are risky to move it over the check for zero denominator.
+    auto SafeToHoist = [](const SCEV *S) {
+      return !SCEVExprContains(S, [](const SCEV *S) {
+                if (const auto *D = dyn_cast<SCEVUDivExpr>(S)) {
+                  if (const auto *SC = dyn_cast<SCEVConstant>(D->getRHS()))
+                    // Division by non-zero constants can be hoisted.
+                    return SC->getValue()->isZero();
+                  // All other divisions should not be moved as they may be
+                  // divisions by zero and should be kept within the
+                  // conditions of the surrounding loops that guard their
+                  // execution (see PR35406).
+                  return true;
+                }
+                return false;
+              });
+    };
     if (SE.isLoopInvariant(S, L)) {
       if (!L) break;
-      if (BasicBlock *Preheader = L->getLoopPreheader())
-        InsertPt = Preheader->getTerminator();
-      else {
+      if (BasicBlock *Preheader = L->getLoopPreheader()) {
+        if (SafeToHoist(S))
+          InsertPt = Preheader->getTerminator();
+      } else {
         // LSR sets the insertion point for AddRec start/step values to the
         // block start to simplify value reuse, even though it's an invalid
         // position. SCEVExpander must correct for this in all cases.
         InsertPt = &*L->getHeader()->getFirstInsertionPt();
       }
     } else {
-      // We can move insertion point only if there is no div or rem operations
-      // otherwise we are risky to move it over the check for zero denominator.
-      auto SafeToHoist = [](const SCEV *S) {
-        return !SCEVExprContains(S, [](const SCEV *S) {
-                  if (const auto *D = dyn_cast<SCEVUDivExpr>(S)) {
-                    if (const auto *SC = dyn_cast<SCEVConstant>(D->getRHS()))
-                      // Division by non-zero constants can be hoisted.
-                      return SC->getValue()->isZero();
-                    // All other divisions should not be moved as they may be
-                    // divisions by zero and should be kept within the
-                    // conditions of the surrounding loops that guard their
-                    // execution (see PR35406).
-                    return true;
-                  }
-                  return false;
-                });
-      };
       // If the SCEV is computable at this level, insert it into the header
       // after the PHIs (and after any other instructions that we've inserted
       // there) so that it is guaranteed to dominate any user inside the loop.
@@ -1775,6 +1776,7 @@
       }
       break;
     }
+  }
 
   // Check to see if we already expanded this here.
   auto I = InsertedExpressions.find(std::make_pair(S, InsertPt));
Index: llvm/test/Transforms/LoopVectorize/pr30806.ll
===================================================================
--- /dev/null
+++ llvm/test/Transforms/LoopVectorize/pr30806.ll
@@ -0,0 +1,65 @@
+; RUN: opt -loop-vectorize -S < %s 2>&1 | FileCheck %s
+
+; Produced from test-case:
+;
+; void testGuardedInnerLoop(uint32_t *ptr, uint32_t denom, uint32_t numer, uint32_t outer_lim)
+; {
+;   for(uint32_t outer_i = 0; outer_i < outer_lim; ++outer_i) {
+;     if (denom > 0) {
+;       const uint32_t lim = numer / denom;
+;
+;       for (uint32_t i = 0; i < lim; ++i)
+;         ptr[i] = 1;
+;     }
+;   }
+; }
+
+
+target datalayout = "e-m:e-i64:64-f80:128-n8:16:32:64-S128-ni:1"
+target triple = "x86_64-unknown-linux-gnu"
+
+define void @testGuardedInnerLoop(i32* %ptr, i32 %denom, i32 %numer, i32 %outer_lim) {
+entry:
+  %cmp1 = icmp eq i32 %outer_lim, 0
+  br i1 %cmp1, label %exit, label %loop1.preheader
+
+; Verify that a 'udiv' does not appear between the 'loop1.preheader' label, and
+; whatever label comes next.
+loop1.preheader:
+; CHECK-LABEL: loop1.preheader:
+; CHECK-NOT: udiv
+; CHECK-LABEL: :
+  br label %loop1
+
+loop1:
+  %outer_i = phi i32 [ %inc1, %loop2.exit ], [ 0, %loop1.preheader ]
+  %0 = add i32 %denom, -1
+  %1 = icmp ult i32 %0, %numer
+  br i1 %1, label %loop2.preheader, label %loop2.exit
+
+; Verify that a 'udiv' does appear between the 'loop2.preheader' label, and
+; whatever label comes next.
+loop2.preheader:
+; CHECK-LABEL: loop2.preheader:
+; CHECK: udiv
+; CHECK-LABEL: :
+  %lim = udiv i32 %numer, %denom
+  %2 = zext i32 %lim to i64
+  br label %loop2
+
+loop2:
+  %indvar.loop2 = phi i64 [ 0, %loop2.preheader ], [ %indvar.loop2.next, %loop2 ]
+  %arrayidx = getelementptr inbounds i32, i32* %ptr, i64 %indvar.loop2
+  store i32 1, i32* %arrayidx, align 4
+  %indvar.loop2.next = add nuw nsw i64 %indvar.loop2, 1
+  %cmp2 = icmp ult i64 %indvar.loop2.next, %2
+  br i1 %cmp2, label %loop2, label %loop2.exit
+
+loop2.exit:
+  %inc1 = add nuw i32 %outer_i, 1
+  %exitcond = icmp eq i32 %inc1, %outer_lim
+  br i1 %exitcond, label %exit, label %loop1
+
+exit:
+  ret void
+}