+; RUN: opt -S -loop-unroll < %s | FileCheck %s
+
+; LLVM should not try to fully unroll this loop.
+
+declare void @f()
+declare void @g()
+declare void @h()
+
+define void @trivial_loop() {
+; CHECK-LABEL: @trivial_loop(
+ entry:
+ br label %loop
+
+ loop:
+ %idx = phi i32 [ 0, %entry ], [ %idx.inc, %loop ]
+ %idx.inc = add i32 %idx, 1
+ call void @f()
+ call void @g()
+ call void @h()
+ call void @f()
+ call void @g()
+ call void @h()
+ call void @f()
+ call void @g()
+ call void @h()
+ call void @f()
+ call void @g()
+ call void @h()
+ call void @f()
+ call void @g()
+ call void @h()
+ %be = icmp slt i32 %idx, 268435456
+ br i1 %be, label %loop, label %exit
+
+; CHECK: loop:
+; CHECK-NEXT: %idx = phi i32 [ 0, %entry ], [ %idx.inc, %loop ]
+; CHECK-NEXT: %idx.inc = add i32 %idx, 1
+; CHECK-NEXT: call void @f()
+; CHECK-NEXT: call void @g()
+; CHECK-NEXT: call void @h()
+; CHECK-NEXT: call void @f()
+; CHECK-NEXT: call void @g()
+; CHECK-NEXT: call void @h()
+; CHECK-NEXT: call void @f()
+; CHECK-NEXT: call void @g()
+; CHECK-NEXT: call void @h()
+; CHECK-NEXT: call void @f()
+; CHECK-NEXT: call void @g()
+; CHECK-NEXT: call void @h()
+; CHECK-NEXT: call void @f()
+; CHECK-NEXT: call void @g()
+; CHECK-NEXT: call void @h()
+; CHECK-NEXT: %be = icmp slt i32 %idx, 268435456
+; CHECK-NEXT: br i1 %be, label %loop, label %exit
+
+ exit:
+ ret void
+}