Index: llvm/lib/Transforms/Utils/BasicBlockUtils.cpp
===================================================================
--- llvm/lib/Transforms/Utils/BasicBlockUtils.cpp
+++ llvm/lib/Transforms/Utils/BasicBlockUtils.cpp
@@ -1518,7 +1518,9 @@
 
   if (LI) {
     if (Loop *L = LI->getLoopFor(Head)) {
-      L->addBasicBlockToLoop(ThenBlock, *LI);
+      // unreachable-terminated blocks cannot belong to any loop.
+      if (!Unreachable)
+        L->addBasicBlockToLoop(ThenBlock, *LI);
       L->addBasicBlockToLoop(Tail, *LI);
     }
   }
Index: llvm/test/Transforms/SimpleLoopUnswitch/guards.ll
===================================================================
--- llvm/test/Transforms/SimpleLoopUnswitch/guards.ll
+++ llvm/test/Transforms/SimpleLoopUnswitch/guards.ll
@@ -2,9 +2,6 @@
 ; RUN: opt -passes='simple-loop-unswitch<nontrivial>' -simple-loop-unswitch-guards -S < %s | FileCheck %s
 ; RUN: opt -passes='loop-mssa(simple-loop-unswitch<nontrivial>),verify<loops>' -simple-loop-unswitch-guards  -verify-memoryssa -S < %s | FileCheck %s
 
-; XFAIL: *
-; REQUIRES: asserts
-
 declare void @llvm.experimental.guard(i1, ...)
 
 define void @test_simple_case(i1 %cond, i32 %N) {
Index: llvm/test/Transforms/SimpleLoopUnswitch/nontrivial-unswitch-skip-selects-in-guards.ll
===================================================================
--- llvm/test/Transforms/SimpleLoopUnswitch/nontrivial-unswitch-skip-selects-in-guards.ll
+++ llvm/test/Transforms/SimpleLoopUnswitch/nontrivial-unswitch-skip-selects-in-guards.ll
@@ -7,9 +7,6 @@
 declare void @llvm.experimental.guard(i1, ...)
 declare void @widget()
 
-; XFAIL: *
-; REQUIRES: asserts
-
 define void @foo(ptr addrspace(1) %arg, i64 %arg1) personality ptr @pluto {
 ; CHECK-LABEL: @foo(
 ; CHECK-NEXT:  bb: