Index: llvm/lib/Transforms/Scalar/GVNHoist.cpp
===================================================================
--- llvm/lib/Transforms/Scalar/GVNHoist.cpp
+++ llvm/lib/Transforms/Scalar/GVNHoist.cpp
@@ -502,12 +502,12 @@
 
   // Return true when it is safe to hoist scalar instructions from all blocks in
   // WL to HoistBB.
-  bool safeToHoistScalar(const BasicBlock *HoistBB,
+  bool safeToHoistScalar(Instruction *I, const BasicBlock *HoistBB,
                          SmallPtrSetImpl<const BasicBlock *> &WL,
                          int &NBBsOnAllPaths) {
     // Enable scalar hoisting at -Oz as it is safe to hoist scalars to a place
     // where they are partially needed.
-    if (OptForMinSize)
+    if (OptForMinSize && isSafeToSpeculativelyExecute(I))
       return true;
 
     // Check that the hoisted expression is needed on all paths.
@@ -574,7 +574,7 @@
       WL.insert(BB);
 
       if (K == InsKind::Scalar) {
-        if (safeToHoistScalar(NewHoistBB, WL, NumBBsOnAllPaths)) {
+        if (safeToHoistScalar(Insn, NewHoistBB, WL, NumBBsOnAllPaths)) {
           // Extend HoistPt to NewHoistPt.
           HoistPt = NewHoistPt;
           HoistBB = NewHoistBB;
Index: llvm/test/Transforms/GVNHoist/hoist-unsafe-pr31729.ll
===================================================================
--- /dev/null
+++ llvm/test/Transforms/GVNHoist/hoist-unsafe-pr31729.ll
@@ -0,0 +1,82 @@
+; RUN: opt -gvn-hoist -S < %s | FileCheck %s
+
+; Check that urem is not hoisted.
+; CHECK-LABEL: @main
+; CHECK: urem
+; CHECK: urem
+; CHECK: urem
+
+@g_x_s = global i32 -470211272, align 4
+@g_z_s = global i32 2007237709, align 4
+@g_x_u = global i32 282475249, align 4
+@g_z_u = global i32 984943658, align 4
+@g_m = global i32 16807, align 4
+@res = common global i32 0, align 4
+
+; Function Attrs:
+define i64 @func() #0 {
+entry:
+  ret i64 1
+}
+
+; Function Attrs:
+define i32 @main() {
+entry:
+  %0 = load volatile i32, i32* @g_x_s, align 4
+  %1 = load volatile i32, i32* @g_z_s, align 4
+  %2 = load volatile i32, i32* @g_x_u, align 4
+  %3 = load volatile i32, i32* @g_z_u, align 4
+  %4 = load volatile i32, i32* @g_m, align 4
+  %call = call i64 @func() #4
+  %conv = sext i32 %1 to i64
+  %cmp = icmp ne i64 %call, %conv
+  br i1 %cmp, label %if.end, label %lor.lhs.false
+
+lor.lhs.false:
+  %div = udiv i32 %4, %1
+  %rem = urem i32 %0, %div
+  %cmp2 = icmp eq i32 %rem, 0
+  br i1 %cmp2, label %if.end, label %if.then
+
+if.then:
+  br label %cleanup
+
+if.end:
+  %call4 = call i64 @func() #4
+  %conv5 = zext i32 %3 to i64
+  %cmp6 = icmp ne i64 %call4, %conv5
+  br i1 %cmp6, label %if.end14, label %lor.lhs.false8
+
+lor.lhs.false8:
+  %div9 = udiv i32 %4, %3
+  %rem10 = urem i32 %0, %div9
+  %cmp11 = icmp eq i32 %rem10, 0
+  br i1 %cmp11, label %if.end14, label %if.then13
+
+if.then13:
+  br label %cleanup
+
+if.end14:
+  %call15 = call i64 @func() #4
+  %cmp17 = icmp ne i64 %call15, %conv
+  br i1 %cmp17, label %if.end25, label %lor.lhs.false19
+
+lor.lhs.false19:
+  %div20 = udiv i32 %4, %1
+  %rem21 = urem i32 %0, %div20
+  %cmp22 = icmp eq i32 %rem21, 0
+  br i1 %cmp22, label %if.end25, label %if.then24
+
+if.then24:
+  br label %cleanup
+
+if.end25:
+  br label %cleanup
+
+cleanup:
+  %retval.0 = phi i32 [ 0, %if.end25 ], [ 1, %if.then24 ], [ 1, %if.then13 ], [ 1, %if.then ]
+  ret i32 %retval.0
+}
+
+attributes #0 = { minsize noinline nounwind optsize uwtable "correctly-rounded-divide-sqrt-fp-math"="false" "disable-tail-calls"="false" "less-precise-fpmad"="false" "no-frame-pointer-elim"="false" "no-infs-fp-math"="false" "no-jump-tables"="false" "no-nans-fp-math"="false" "no-signed-zeros-fp-math"="false" "no-trapping-math"="false" "stack-protector-buffer-size"="8" "target-cpu"="x86-64" "target-features"="+fxsr,+mmx,+sse,+sse2,+x87" "unsafe-fp-math"="false" "use-soft-float"="false" }
+