diff --git a/llvm/test/Transforms/LoopVectorize/ARM/mve-reductions.ll b/llvm/test/Transforms/LoopVectorize/ARM/mve-reductions.ll
@@ -1,5 +1,5 @@
 ; NOTE: Assertions have been autogenerated by utils/update_test_checks.py
-; RUN: opt -loop-vectorize -instcombine -simplifycfg -tail-predication=enabled < %s -S -o - | FileCheck %s
+; RUN: opt -loop-vectorize -instcombine -simplifycfg -simplifycfg-require-and-preserve-domtree=1 -tail-predication=enabled < %s -S -o - | FileCheck %s
 
 target datalayout = "e-m:e-p:32:32-Fi8-i64:64-v128:64:128-a:0:32-n32-S64"
 target triple = "thumbv8.1m.main-arm-none-eabi"

diff --git a/llvm/test/Transforms/LoopVectorize/ARM/pointer_iv.ll b/llvm/test/Transforms/LoopVectorize/ARM/pointer_iv.ll
@@ -1,5 +1,5 @@
 ; NOTE: Assertions have been autogenerated by utils/update_test_checks.py
-; RUN: opt -loop-vectorize -S -mtriple=thumbv8.1m.main-none-none-eabi -mattr=+mve.fp,mve1beat -dce -instcombine --simplifycfg -tail-predication=disabled < %s | FileCheck %s
+; RUN: opt -loop-vectorize -S -mtriple=thumbv8.1m.main-none-none-eabi -mattr=+mve.fp,mve1beat -dce -instcombine --simplifycfg -simplifycfg-require-and-preserve-domtree=1 -tail-predication=disabled < %s | FileCheck %s
 
 target datalayout = "e-m:e-p:32:32-Fi8-i64:64-v128:64:128-a:0:32-n32-S64"
 target triple = "thumbv8.1m.main-none-none-eabi"

diff --git a/llvm/test/Transforms/LoopVectorize/ARM/tail-fold-multiple-icmps.ll b/llvm/test/Transforms/LoopVectorize/ARM/tail-fold-multiple-icmps.ll
@@ -1,5 +1,5 @@
 ; NOTE: Assertions have been autogenerated by utils/update_test_checks.py
-; RUN: opt -mtriple=thumbv8.1m.main-none-none-eabi -mattr=+mve -tail-predication=enabled -loop-vectorize -instcombine -simplifycfg %s -S -o - | FileCheck %s
+; RUN: opt -mtriple=thumbv8.1m.main-none-none-eabi -mattr=+mve -tail-predication=enabled -loop-vectorize -instcombine -simplifycfg -simplifycfg-require-and-preserve-domtree=1 %s -S -o - | FileCheck %s
 
 target datalayout = "e-m:e-p:32:32-Fi8-i64:64-v128:64:128-a:0:32-n32-S64"
 

diff --git a/llvm/test/Transforms/LoopVectorize/PowerPC/widened-massv-vfabi-attr.ll b/llvm/test/Transforms/LoopVectorize/PowerPC/widened-massv-vfabi-attr.ll
@@ -1,7 +1,7 @@
 ; NOTE: Assertions have been autogenerated by utils/update_test_checks.py
 ; RUN: opt -vectorizer-maximize-bandwidth -mtriple=powerpc64le-- -S \
 ; RUN:   -targetlibinfo -loop-simplify -loop-rotate -loop-vectorize \
-; RUN:   -instcombine -simplifycfg -force-vector-interleave=1 < %s | FileCheck %s
+; RUN:   -instcombine -simplifycfg -simplifycfg-require-and-preserve-domtree=1 -force-vector-interleave=1 < %s | FileCheck %s
 define dso_local double @test(float* %Arr) {
 ; CHECK-LABEL: @test(
 ; CHECK-NEXT:  entry:

diff --git a/llvm/test/Transforms/LoopVectorize/X86/float-induction-x86.ll b/llvm/test/Transforms/LoopVectorize/X86/float-induction-x86.ll
@@ -1,5 +1,5 @@
 ; NOTE: Assertions have been autogenerated by utils/update_test_checks.py
-; RUN: opt < %s  -O3 -simplifycfg -keep-loops=false -mcpu=core-avx2 -mtriple=x86_64-unknown-linux-gnu -S | FileCheck --check-prefix AUTO_VEC %s
+; RUN: opt < %s  -O3 -simplifycfg -simplifycfg-require-and-preserve-domtree=1 -keep-loops=false -mcpu=core-avx2 -mtriple=x86_64-unknown-linux-gnu -S | FileCheck --check-prefix AUTO_VEC %s
 
 target datalayout = "e-m:e-p270:32:32-p271:32:32-p272:64:64-i64:64-f80:128-n8:16:32:64-S128"
 

diff --git a/llvm/test/Transforms/LoopVectorize/X86/pr42674.ll b/llvm/test/Transforms/LoopVectorize/X86/pr42674.ll
@@ -1,5 +1,5 @@
 ; NOTE: Assertions have been autogenerated by utils/update_test_checks.py
-; RUN: opt %s -loop-vectorize -instcombine -simplifycfg -mtriple=x86_64-unknown-linux-gnu -mattr=avx512vl,avx512dq,avx512bw -S | FileCheck %s
+; RUN: opt %s -loop-vectorize -instcombine -simplifycfg -simplifycfg-require-and-preserve-domtree=1 -mtriple=x86_64-unknown-linux-gnu -mattr=avx512vl,avx512dq,avx512bw -S | FileCheck %s
 
 @bytes = global [128 x i8] zeroinitializer, align 16
 

diff --git a/llvm/test/Transforms/LoopVectorize/X86/x86-interleaved-accesses-masked-group.ll b/llvm/test/Transforms/LoopVectorize/X86/x86-interleaved-accesses-masked-group.ll
@@ -1,6 +1,6 @@
 ; NOTE: Assertions have been autogenerated by utils/update_test_checks.py
-; RUN: opt -mcpu=skx -S -loop-vectorize -instcombine -simplifycfg -force-vector-width=8 -force-vector-interleave=1 -enable-interleaved-mem-accesses < %s | FileCheck %s -check-prefix=DISABLED_MASKED_STRIDED
-; RUN: opt -mcpu=skx -S -loop-vectorize -instcombine -simplifycfg -force-vector-width=8 -force-vector-interleave=1 -enable-interleaved-mem-accesses  -enable-masked-interleaved-mem-accesses < %s | FileCheck %s -check-prefix=ENABLED_MASKED_STRIDED
+; RUN: opt -mcpu=skx -S -loop-vectorize -instcombine -simplifycfg -simplifycfg-require-and-preserve-domtree=1 -force-vector-width=8 -force-vector-interleave=1 -enable-interleaved-mem-accesses < %s | FileCheck %s -check-prefix=DISABLED_MASKED_STRIDED
+; RUN: opt -mcpu=skx -S -loop-vectorize -instcombine -simplifycfg -simplifycfg-require-and-preserve-domtree=1 -force-vector-width=8 -force-vector-interleave=1 -enable-interleaved-mem-accesses  -enable-masked-interleaved-mem-accesses < %s | FileCheck %s -check-prefix=ENABLED_MASKED_STRIDED
 
 target datalayout = "e-m:e-p:32:32-f64:32:64-f80:32-n8:16:32-S128"
 target triple = "i386-unknown-linux-gnu"

diff --git a/llvm/test/Transforms/LoopVectorize/X86/x86-predication.ll b/llvm/test/Transforms/LoopVectorize/X86/x86-predication.ll
@@ -1,4 +1,4 @@
-; RUN: opt < %s -mattr=avx -force-vector-width=2 -force-vector-interleave=1 -loop-vectorize -simplifycfg -S | FileCheck %s
+; RUN: opt < %s -mattr=avx -force-vector-width=2 -force-vector-interleave=1 -loop-vectorize -simplifycfg -simplifycfg-require-and-preserve-domtree=1 -S | FileCheck %s
 ; RUN: opt -mcpu=skylake-avx512 -S -force-vector-width=8 -force-vector-interleave=1 -loop-vectorize < %s | FileCheck %s --check-prefix=SINK-GATHER
 
 target datalayout = "e-p:64:64:64-i1:8:8-i8:8:8-i16:16:16-i32:32:32-i64:64:64-f32:32:32-f64:64:64-v64:64:64-v128:128:128-a0:0:64-s0:64:64-f80:128:128-n8:16:32:64-S128"

diff --git a/llvm/test/Transforms/LoopVectorize/float-induction.ll b/llvm/test/Transforms/LoopVectorize/float-induction.ll
@@ -1,7 +1,7 @@
 ; RUN: opt < %s  -loop-vectorize -force-vector-interleave=1 -force-vector-width=4 -dce -instcombine -S | FileCheck --check-prefix VEC4_INTERL1 %s
 ; RUN: opt < %s  -loop-vectorize -force-vector-interleave=2 -force-vector-width=4 -dce -instcombine -S | FileCheck --check-prefix VEC4_INTERL2 %s
 ; RUN: opt < %s  -loop-vectorize -force-vector-interleave=2 -force-vector-width=1 -dce -instcombine -S | FileCheck --check-prefix VEC1_INTERL2 %s
-; RUN: opt < %s  -loop-vectorize -force-vector-interleave=1 -force-vector-width=2 -dce -simplifycfg -instcombine -simplifycfg -keep-loops=false -S | FileCheck --check-prefix VEC2_INTERL1_PRED_STORE %s
+; RUN: opt < %s  -loop-vectorize -force-vector-interleave=1 -force-vector-width=2 -dce -simplifycfg -simplifycfg-require-and-preserve-domtree=1 -instcombine -simplifycfg -simplifycfg-require-and-preserve-domtree=1 -keep-loops=false -S | FileCheck --check-prefix VEC2_INTERL1_PRED_STORE %s
 
 @fp_inc = common global float 0.000000e+00, align 4
 
@@ -232,10 +232,10 @@ for.body:                                         ; preds = %for.body, %for.body
   %exitcond = icmp eq i32 %lftr.wideiv, %N
   br i1 %exitcond, label %for.end.loopexit, label %for.body
 
-for.end.loopexit:                                 
+for.end.loopexit:
   br label %for.end
 
-for.end: 
+for.end:
   ret void
 }
 

diff --git a/llvm/test/Transforms/LoopVectorize/hints-trans.ll b/llvm/test/Transforms/LoopVectorize/hints-trans.ll
@@ -1,5 +1,5 @@
-; RUN: opt -S -loop-vectorize -force-vector-interleave=1 -force-vector-width=4 -instsimplify -simplifycfg < %s | FileCheck %s
-; Note: -instsimplify -simplifycfg remove the (now dead) original loop, making
+; RUN: opt -S -loop-vectorize -force-vector-interleave=1 -force-vector-width=4 -instsimplify -simplifycfg -simplifycfg-require-and-preserve-domtree=1 < %s | FileCheck %s
+; Note: -instsimplify -simplifycfg -simplifycfg-require-and-preserve-domtree=1 remove the (now dead) original loop, making
 ; it easy to test that the llvm.loop.unroll.disable hint is still present.
 target datalayout = "e-m:e-i64:64-f80:128-n8:16:32:64-S128"
 

diff --git a/llvm/test/Transforms/LoopVectorize/if-pred-not-when-safe.ll b/llvm/test/Transforms/LoopVectorize/if-pred-not-when-safe.ll
@@ -1,4 +1,4 @@
-; RUN: opt -S -force-vector-width=2 -force-vector-interleave=1 -loop-vectorize -verify-loop-info -simplifycfg < %s | FileCheck %s
+; RUN: opt -S -force-vector-width=2 -force-vector-interleave=1 -loop-vectorize -verify-loop-info -simplifycfg -simplifycfg-require-and-preserve-domtree=1 < %s | FileCheck %s
 
 target datalayout = "e-m:e-i64:64-f80:128-n8:16:32:64-S128"
 

diff --git a/llvm/test/Transforms/LoopVectorize/tbaa-nodep.ll b/llvm/test/Transforms/LoopVectorize/tbaa-nodep.ll
@@ -1,5 +1,5 @@
-; RUN: opt < %s  -tbaa -basic-aa -loop-vectorize -force-vector-interleave=1 -force-vector-width=4 -dce -instcombine -simplifycfg -S | FileCheck %s
-; RUN: opt < %s  -basic-aa -loop-vectorize -force-vector-interleave=1 -force-vector-width=4 -dce -instcombine -simplifycfg -S | FileCheck %s --check-prefix=CHECK-NOTBAA
+; RUN: opt < %s  -tbaa -basic-aa -loop-vectorize -force-vector-interleave=1 -force-vector-width=4 -dce -instcombine -simplifycfg -simplifycfg-require-and-preserve-domtree=1 -S | FileCheck %s
+; RUN: opt < %s  -basic-aa -loop-vectorize -force-vector-interleave=1 -force-vector-width=4 -dce -instcombine -simplifycfg -simplifycfg-require-and-preserve-domtree=1 -S | FileCheck %s --check-prefix=CHECK-NOTBAA
 target datalayout = "e-m:e-i64:64-f80:128-n8:16:32:64-S128"
 
 ; Function Attrs: nounwind uwtable

diff --git a/llvm/test/Transforms/LoopVectorize/vectorize-once.ll b/llvm/test/Transforms/LoopVectorize/vectorize-once.ll
@@ -1,4 +1,4 @@
-; RUN: opt < %s -loop-vectorize -force-vector-interleave=1 -force-vector-width=4 -dce -instcombine -S -simplifycfg | FileCheck %s
+; RUN: opt < %s -loop-vectorize -force-vector-interleave=1 -force-vector-width=4 -dce -instcombine -S -simplifycfg -simplifycfg-require-and-preserve-domtree=1 | FileCheck %s
 
 target datalayout = "e-p:64:64:64-i1:8:8-i8:8:8-i16:16:16-i32:32:32-i64:64:64-f32:32:32-f64:64:64-v64:64:64-v128:128:128-a0:0:64-s0:64:64-f80:128:128-n8:16:32:64-S128"
 

diff --git a/llvm/test/Transforms/SCCP/2002-05-21-InvalidSimplify.ll b/llvm/test/Transforms/SCCP/2002-05-21-InvalidSimplify.ll
@@ -2,7 +2,7 @@
 ; this is in fact NOT the case, so the return should still be alive in the code
 ; after sccp and CFG simplification have been performed.
 ;
-; RUN: opt < %s -sccp -simplifycfg -S | \
+; RUN: opt < %s -sccp -simplifycfg -simplifycfg-require-and-preserve-domtree=1 -S | \
 ; RUN:   grep ret
 
 define void @old_main() {

diff --git a/llvm/test/Transforms/SCCP/2003-06-24-OverdefinedPHIValue.ll b/llvm/test/Transforms/SCCP/2003-06-24-OverdefinedPHIValue.ll
@@ -1,4 +1,4 @@
-; RUN: opt < %s -sccp -simplifycfg -S | \
+; RUN: opt < %s -sccp -simplifycfg -simplifycfg-require-and-preserve-domtree=1 -S | \
 ; RUN:   not grep then:
 
 define void @cprop_test11(i32* %data.1) {

diff --git a/llvm/test/Transforms/SCCP/calltest.ll b/llvm/test/Transforms/SCCP/calltest.ll
@@ -1,4 +1,4 @@
-; RUN: opt < %s -sccp -loop-deletion -simplifycfg -S | FileCheck %s
+; RUN: opt < %s -sccp -loop-deletion -simplifycfg -simplifycfg-require-and-preserve-domtree=1 -S | FileCheck %s
 
 declare double @sqrt(double) readnone nounwind
 %empty = type {}

diff --git a/llvm/test/Transforms/SimplifyCFG/2002-05-21-PHIElimination.ll b/llvm/test/Transforms/SimplifyCFG/2002-05-21-PHIElimination.ll
@@ -4,7 +4,7 @@
 ;
 ; Which is not valid SSA
 ;
-; RUN: opt < %s -simplifycfg | llvm-dis
+; RUN: opt < %s -simplifycfg -simplifycfg-require-and-preserve-domtree=1 | llvm-dis
 
 define void @test() {
 ; <label>:0

diff --git a/llvm/test/Transforms/SimplifyCFG/2003-03-07-DominateProblem.ll b/llvm/test/Transforms/SimplifyCFG/2003-03-07-DominateProblem.ll
@@ -1,4 +1,4 @@
-; RUN: opt < %s -simplifycfg -disable-output
+; RUN: opt < %s -simplifycfg -simplifycfg-require-and-preserve-domtree=1 -disable-output
 
 define void @test(i32* %ldo, i1 %c, i1 %d) {
 bb9:

diff --git a/llvm/test/Transforms/SimplifyCFG/2003-08-05-InvokeCrash.ll b/llvm/test/Transforms/SimplifyCFG/2003-08-05-InvokeCrash.ll
@@ -1,6 +1,6 @@
 ; Do not remove the invoke!
 ;
-; RUN: opt < %s -simplifycfg -disable-output
+; RUN: opt < %s -simplifycfg -simplifycfg-require-and-preserve-domtree=1 -disable-output
 
 define i32 @test() personality i8* bitcast (i32 (...)* @__gxx_personality_v0 to i8*) {
 	%A = invoke i32 @test( )

diff --git a/llvm/test/Transforms/SimplifyCFG/2003-08-17-BranchFold.ll b/llvm/test/Transforms/SimplifyCFG/2003-08-17-BranchFold.ll
@@ -1,7 +1,7 @@
 ; This test checks to make sure that 'br X, Dest, Dest' is folded into
 ; 'br Dest'
 
-; RUN: opt < %s -simplifycfg -S | FileCheck %s
+; RUN: opt < %s -simplifycfg -simplifycfg-require-and-preserve-domtree=1 -S | FileCheck %s
 
 declare void @noop()
 

diff --git a/llvm/test/Transforms/SimplifyCFG/2003-08-17-BranchFoldOrdering.ll b/llvm/test/Transforms/SimplifyCFG/2003-08-17-BranchFoldOrdering.ll
@@ -3,7 +3,7 @@
 ; due to the fact that the SimplifyCFG function does not use
 ; the ConstantFoldTerminator function.
 
-; RUN: opt < %s -simplifycfg -S | FileCheck %s
+; RUN: opt < %s -simplifycfg -simplifycfg-require-and-preserve-domtree=1 -S | FileCheck %s
 
 ; CHECK-NOT: br i1 %c2
 

diff --git a/llvm/test/Transforms/SimplifyCFG/2003-08-17-FoldSwitch-dbg.ll b/llvm/test/Transforms/SimplifyCFG/2003-08-17-FoldSwitch-dbg.ll
@@ -1,4 +1,4 @@
-; RUN: opt < %s -simplifycfg -S | FileCheck %s
+; RUN: opt < %s -simplifycfg -simplifycfg-require-and-preserve-domtree=1 -S | FileCheck %s
 
 ; CHECK-NOT: switch
         %llvm.dbg.anchor.type = type { i32, i32 }

diff --git a/llvm/test/Transforms/SimplifyCFG/2003-08-17-FoldSwitch.ll b/llvm/test/Transforms/SimplifyCFG/2003-08-17-FoldSwitch.ll
@@ -1,5 +1,5 @@
 ; NOTE: Assertions have been autogenerated by update_test_checks.py
-; RUN: opt < %s -simplifycfg -S | FileCheck %s
+; RUN: opt < %s -simplifycfg -simplifycfg-require-and-preserve-domtree=1 -S | FileCheck %s
 
 ; Test normal folding
 define i32 @test1() {

diff --git a/llvm/test/Transforms/SimplifyCFG/2005-08-01-PHIUpdateFail.ll b/llvm/test/Transforms/SimplifyCFG/2005-08-01-PHIUpdateFail.ll
@@ -1,4 +1,4 @@
-; RUN: opt < %s -simplifycfg -disable-output
+; RUN: opt < %s -simplifycfg -simplifycfg-require-and-preserve-domtree=1 -disable-output
 ; END.
 
 define void @main() {

diff --git a/llvm/test/Transforms/SimplifyCFG/2005-10-02-InvokeSimplify.ll b/llvm/test/Transforms/SimplifyCFG/2005-10-02-InvokeSimplify.ll
@@ -1,4 +1,4 @@
-; RUN: opt < %s -simplifycfg -disable-output
+; RUN: opt < %s -simplifycfg -simplifycfg-require-and-preserve-domtree=1 -disable-output
 
 define i1 @foo() personality i8* bitcast (i32 (...)* @__gxx_personality_v0 to i8*) {
 	%X = invoke i1 @foo( )

diff --git a/llvm/test/Transforms/SimplifyCFG/2005-12-03-IncorrectPHIFold.ll b/llvm/test/Transforms/SimplifyCFG/2005-12-03-IncorrectPHIFold.ll
@@ -1,6 +1,6 @@
 ; Make sure this doesn't turn into an infinite loop
 
-; RUN: opt < %s -simplifycfg -instsimplify -simplifycfg | llvm-dis | FileCheck %s
+; RUN: opt < %s -simplifycfg -simplifycfg-require-and-preserve-domtree=1 -instsimplify -simplifycfg -simplifycfg-require-and-preserve-domtree=1 | llvm-dis | FileCheck %s
 
 %struct.anon = type { i32, i32, i32, i32, [1024 x i8] }
 @_zero_ = external global %struct.anon*		; <%struct.anon**> [#uses=2]

diff --git a/llvm/test/Transforms/SimplifyCFG/2006-02-17-InfiniteUnroll.ll b/llvm/test/Transforms/SimplifyCFG/2006-02-17-InfiniteUnroll.ll
@@ -1,4 +1,4 @@
-; RUN: opt < %s -simplifycfg -disable-output
+; RUN: opt < %s -simplifycfg -simplifycfg-require-and-preserve-domtree=1 -disable-output
 
 define void @polnel_() {
 entry:

diff --git a/llvm/test/Transforms/SimplifyCFG/2006-06-12-InfLoop.ll b/llvm/test/Transforms/SimplifyCFG/2006-06-12-InfLoop.ll
@@ -1,4 +1,4 @@
-; RUN: opt < %s -simplifycfg -disable-output
+; RUN: opt < %s -simplifycfg -simplifycfg-require-and-preserve-domtree=1 -disable-output
 ; END.
 
 define void @main(i32 %c) {

diff --git a/llvm/test/Transforms/SimplifyCFG/2006-08-03-Crash.ll b/llvm/test/Transforms/SimplifyCFG/2006-08-03-Crash.ll
@@ -1,4 +1,4 @@
-; RUN: opt < %s -gvn -simplifycfg -disable-output
+; RUN: opt < %s -gvn -simplifycfg -simplifycfg-require-and-preserve-domtree=1 -disable-output
 ; PR867
 
 target datalayout = "E-p:32:32"

diff --git a/llvm/test/Transforms/SimplifyCFG/2006-10-19-UncondDiv.ll b/llvm/test/Transforms/SimplifyCFG/2006-10-19-UncondDiv.ll
@@ -1,5 +1,5 @@
 ; PR957
-; RUN: opt < %s -simplifycfg -S | FileCheck %s
+; RUN: opt < %s -simplifycfg -simplifycfg-require-and-preserve-domtree=1 -S | FileCheck %s
 
 ; CHECK-NOT: select
 

diff --git a/llvm/test/Transforms/SimplifyCFG/2007-11-22-InvokeNoUnwind.ll b/llvm/test/Transforms/SimplifyCFG/2007-11-22-InvokeNoUnwind.ll
@@ -1,4 +1,4 @@
-; RUN: opt < %s -simplifycfg -S | FileCheck %s
+; RUN: opt < %s -simplifycfg -simplifycfg-require-and-preserve-domtree=1 -S | FileCheck %s
 
 ; CHECK-NOT: invoke
 

diff --git a/llvm/test/Transforms/SimplifyCFG/2007-12-21-Crash.ll b/llvm/test/Transforms/SimplifyCFG/2007-12-21-Crash.ll
@@ -1,4 +1,4 @@
-;RUN: opt < %s -simplifycfg -disable-output
+;RUN: opt < %s -simplifycfg -simplifycfg-require-and-preserve-domtree=1 -disable-output
 target datalayout = "e-p:32:32:32-i1:8:8-i8:8:8-i16:16:16-i32:32:32-i64:32:64-f32:32:32-f64:32:64-v64:64:64-v128:128:128-a0:0:64-f80:128:128"
 
 define i32 @bork() nounwind  {

diff --git a/llvm/test/Transforms/SimplifyCFG/2008-01-02-hoist-fp-add.ll b/llvm/test/Transforms/SimplifyCFG/2008-01-02-hoist-fp-add.ll
@@ -1,5 +1,5 @@
 ; The phi should not be eliminated in this case, because the divide op could trap.
-; RUN: opt < %s -simplifycfg -S | FileCheck %s
+; RUN: opt < %s -simplifycfg -simplifycfg-require-and-preserve-domtree=1 -S | FileCheck %s
 
 target datalayout = "e-p:32:32:32-i1:8:8-i8:8:8-i16:16:16-i32:32:32-i64:32:64-f32:32:32-f64:32:64-v64:64:64-v128:128:128-a0:0:64-f80:128:128"
 target triple = "i686-apple-darwin8"

diff --git a/llvm/test/Transforms/SimplifyCFG/2008-05-16-PHIBlockMerge.ll b/llvm/test/Transforms/SimplifyCFG/2008-05-16-PHIBlockMerge.ll
@@ -1,4 +1,4 @@
-; RUN: opt < %s -simplifycfg -S > %t
+; RUN: opt < %s -simplifycfg -simplifycfg-require-and-preserve-domtree=1 -S > %t
 ; RUN: not grep "^BB.tomerge" %t
 ; RUN: grep "^BB.nomerge" %t | count 4
 

diff --git a/llvm/test/Transforms/SimplifyCFG/2008-09-17-SpeculativeHoist.ll b/llvm/test/Transforms/SimplifyCFG/2008-09-17-SpeculativeHoist.ll
@@ -1,4 +1,4 @@
-; RUN: opt < %s -simplifycfg -disable-output
+; RUN: opt < %s -simplifycfg -simplifycfg-require-and-preserve-domtree=1 -disable-output
 ; PR 2800
 
 define void @foo() {

diff --git a/llvm/test/Transforms/SimplifyCFG/2009-05-12-externweak.ll b/llvm/test/Transforms/SimplifyCFG/2009-05-12-externweak.ll
@@ -1,4 +1,4 @@
-; RUN: opt < %s -simplifycfg -S | not grep select
+; RUN: opt < %s -simplifycfg -simplifycfg-require-and-preserve-domtree=1 -S | not grep select
 ; ModuleID = '<stdin>'
 target datalayout = "e-p:32:32:32-i1:8:8-i8:8:8-i16:16:16-i32:32:32-i64:32:64-f32:32:32-f64:32:64-v64:64:64-v128:128:128-a0:0:64-f80:128:128"
 target triple = "i386-apple-darwin10.0"

diff --git a/llvm/test/Transforms/SimplifyCFG/AArch64/cttz-ctlz.ll b/llvm/test/Transforms/SimplifyCFG/AArch64/cttz-ctlz.ll
@@ -1,4 +1,4 @@
-; RUN: opt -S -simplifycfg -mtriple=aarch64 < %s | FileCheck %s
+; RUN: opt -S -simplifycfg -simplifycfg-require-and-preserve-domtree=1 -mtriple=aarch64 < %s | FileCheck %s
 
 define i32 @ctlz(i32 %A) {
 ; CHECK-LABEL: @ctlz(

diff --git a/llvm/test/Transforms/SimplifyCFG/AArch64/prefer-fma.ll b/llvm/test/Transforms/SimplifyCFG/AArch64/prefer-fma.ll
@@ -1,4 +1,4 @@
-; RUN: opt < %s -mtriple=aarch64-linux-gnu -simplifycfg -hoist-common-insts=true -enable-unsafe-fp-math -S >%t
+; RUN: opt < %s -mtriple=aarch64-linux-gnu -simplifycfg -simplifycfg-require-and-preserve-domtree=1 -hoist-common-insts=true -enable-unsafe-fp-math -S >%t
 ; RUN: FileCheck %s < %t
 ; ModuleID = 't.cc'
 

diff --git a/llvm/test/Transforms/SimplifyCFG/AMDGPU/cttz-ctlz.ll b/llvm/test/Transforms/SimplifyCFG/AMDGPU/cttz-ctlz.ll
@@ -1,5 +1,5 @@
-; RUN: opt -S -simplifycfg -mtriple=amdgcn-unknown-unknown -mcpu=tahiti < %s | FileCheck -check-prefix=SI -check-prefix=ALL %s
-; RUN: opt -S -simplifycfg -mtriple=amdgcn-unknown-unknown -mcpu=tonga < %s | FileCheck -check-prefix=SI -check-prefix=ALL %s
+; RUN: opt -S -simplifycfg -simplifycfg-require-and-preserve-domtree=1 -mtriple=amdgcn-unknown-unknown -mcpu=tahiti < %s | FileCheck -check-prefix=SI -check-prefix=ALL %s
+; RUN: opt -S -simplifycfg -simplifycfg-require-and-preserve-domtree=1 -mtriple=amdgcn-unknown-unknown -mcpu=tonga < %s | FileCheck -check-prefix=SI -check-prefix=ALL %s
 
 
 define i64 @test1(i64 %A) {

diff --git a/llvm/test/Transforms/SimplifyCFG/ARM/cttz-ctlz.ll b/llvm/test/Transforms/SimplifyCFG/ARM/cttz-ctlz.ll
@@ -1,5 +1,5 @@
 ; NOTE: Assertions have been autogenerated by utils/update_test_checks.py
-; RUN: opt -S -simplifycfg -mtriple=arm -mattr=+v6t2 < %s | FileCheck %s
+; RUN: opt -S -simplifycfg -simplifycfg-require-and-preserve-domtree=1 -mtriple=arm -mattr=+v6t2 < %s | FileCheck %s
 
 define i32 @ctlz(i32 %A) {
 ; CHECK-LABEL: @ctlz(

diff --git a/llvm/test/Transforms/SimplifyCFG/ARM/select-costs.ll b/llvm/test/Transforms/SimplifyCFG/ARM/select-costs.ll
@@ -1,8 +1,8 @@
 ; NOTE: Assertions have been autogenerated by utils/update_test_checks.py
-; RUN: opt -mtriple=thumbv8.1m.main -simplifycfg -S %s -o - | FileCheck %s --check-prefix=V8M
-; RUN: opt -mtriple=thumbv8m.main -simplifycfg -S %s -o - | FileCheck %s --check-prefix=V8M
-; RUN: opt -mtriple=thumbv8m.base -simplifycfg -S %s -o - | FileCheck %s --check-prefix=V8M
-; RUN: opt -mtriple=armv8a -simplifycfg -S %s -o - | FileCheck %s --check-prefix=V8A
+; RUN: opt -mtriple=thumbv8.1m.main -simplifycfg -simplifycfg-require-and-preserve-domtree=1 -S %s -o - | FileCheck %s --check-prefix=V8M
+; RUN: opt -mtriple=thumbv8m.main -simplifycfg -simplifycfg-require-and-preserve-domtree=1 -S %s -o - | FileCheck %s --check-prefix=V8M
+; RUN: opt -mtriple=thumbv8m.base -simplifycfg -simplifycfg-require-and-preserve-domtree=1 -S %s -o - | FileCheck %s --check-prefix=V8M
+; RUN: opt -mtriple=armv8a -simplifycfg -simplifycfg-require-and-preserve-domtree=1 -S %s -o - | FileCheck %s --check-prefix=V8A
 
 ; Test that the phis from for.inc.preheader aren't hoisted into sw.bb92 because
 ; the cost is too great - we can make a better decision later on.

diff --git a/llvm/test/Transforms/SimplifyCFG/ARM/switch-to-lookup-table-constant-expr.ll b/llvm/test/Transforms/SimplifyCFG/ARM/switch-to-lookup-table-constant-expr.ll
@@ -1,5 +1,5 @@
 ; NOTE: Assertions have been autogenerated by utils/update_test_checks.py
-; RUN: opt -S -simplifycfg < %s | FileCheck %s
+; RUN: opt -S -simplifycfg -simplifycfg-require-and-preserve-domtree=1 < %s | FileCheck %s
 
 target datalayout = "e-m:e-p:32:32-i64:64-v128:64:128-a:0:32-n32-S64"
 target triple = "armv7a--none-eabi"

diff --git a/llvm/test/Transforms/SimplifyCFG/EmptyBlockMerge.ll b/llvm/test/Transforms/SimplifyCFG/EmptyBlockMerge.ll
@@ -1,6 +1,6 @@
 ; Basic block #2 should not be merged into BB #3!
 ;
-; RUN: opt < %s -simplifycfg -S | FileCheck %s
+; RUN: opt < %s -simplifycfg -simplifycfg-require-and-preserve-domtree=1 -S | FileCheck %s
 
 declare void @foo()
 

diff --git a/llvm/test/Transforms/SimplifyCFG/EqualPHIEdgeBlockMerge.ll b/llvm/test/Transforms/SimplifyCFG/EqualPHIEdgeBlockMerge.ll
@@ -1,6 +1,6 @@
 ; Test merging of blocks with phi nodes.
 ;
-; RUN: opt < %s -simplifycfg -S > %t
+; RUN: opt < %s -simplifycfg -simplifycfg-require-and-preserve-domtree=1 -S > %t
 ; RUN: not grep N: %t
 ; RUN: not grep X: %t
 ; RUN: not grep 'switch i32[^U]+%U' %t

diff --git a/llvm/test/Transforms/SimplifyCFG/ForwardSwitchConditionToPHI.ll b/llvm/test/Transforms/SimplifyCFG/ForwardSwitchConditionToPHI.ll
@@ -1,6 +1,6 @@
 ; NOTE: Assertions have been autogenerated by utils/update_test_checks.py
-; RUN: opt < %s -simplifycfg -forward-switch-cond=false -S | FileCheck %s --check-prefix=NO_FWD
-; RUN: opt < %s -simplifycfg -forward-switch-cond=true  -S | FileCheck %s --check-prefix=FWD
+; RUN: opt < %s -simplifycfg -simplifycfg-require-and-preserve-domtree=1 -forward-switch-cond=false -S | FileCheck %s --check-prefix=NO_FWD
+; RUN: opt < %s -simplifycfg -simplifycfg-require-and-preserve-domtree=1 -forward-switch-cond=true  -S | FileCheck %s --check-prefix=FWD
 
 ; RUN: opt < %s -passes='simplify-cfg<no-forward-switch-cond>' -S | FileCheck %s --check-prefix=NO_FWD
 ; RUN: opt < %s -passes='simplify-cfg<forward-switch-cond>' -S | FileCheck %s --check-prefix=FWD

diff --git a/llvm/test/Transforms/SimplifyCFG/Mips/cttz-ctlz.ll b/llvm/test/Transforms/SimplifyCFG/Mips/cttz-ctlz.ll
@@ -1,4 +1,4 @@
-; RUN: opt -S -simplifycfg -mtriple=mips-linux-gnu < %s | FileCheck %s
+; RUN: opt -S -simplifycfg -simplifycfg-require-and-preserve-domtree=1 -mtriple=mips-linux-gnu < %s | FileCheck %s
 
 define i32 @ctlz(i32 %A) {
 ; CHECK-LABEL: @ctlz(

diff --git a/llvm/test/Transforms/SimplifyCFG/PHINode.ll b/llvm/test/Transforms/SimplifyCFG/PHINode.ll
@@ -1,7 +1,7 @@
-; -simplifycfg is not folding blocks if there is a PHI node involved.  This
+; -simplifycfg -simplifycfg-require-and-preserve-domtree=1 is not folding blocks if there is a PHI node involved.  This
 ; should be fixed eventually
 
-; RUN: opt < %s -simplifycfg -S | FileCheck %s
+; RUN: opt < %s -simplifycfg -simplifycfg-require-and-preserve-domtree=1 -S | FileCheck %s
 
 define i32 @main(i32 %argc) {
 ; <label>:0

diff --git a/llvm/test/Transforms/SimplifyCFG/PR16069.ll b/llvm/test/Transforms/SimplifyCFG/PR16069.ll
@@ -1,5 +1,5 @@
 ; NOTE: Assertions have been autogenerated by update_test_checks.py
-; RUN: opt < %s -simplifycfg -S | FileCheck %s
+; RUN: opt < %s -simplifycfg -simplifycfg-require-and-preserve-domtree=1 -S | FileCheck %s
 
 @b = extern_weak global i32
 

diff --git a/llvm/test/Transforms/SimplifyCFG/PR17073.ll b/llvm/test/Transforms/SimplifyCFG/PR17073.ll
@@ -1,5 +1,5 @@
 ; NOTE: Assertions have been autogenerated by utils/update_test_checks.py
-; RUN: opt < %s -simplifycfg -S | FileCheck %s
+; RUN: opt < %s -simplifycfg -simplifycfg-require-and-preserve-domtree=1 -S | FileCheck %s
 
 ; In PR17073 ( http://llvm.org/pr17073 ), we illegally hoisted an operation that can trap.
 ; The first test confirms that we don't do that when the trapping op is reached by the current BB (block1).

diff --git a/llvm/test/Transforms/SimplifyCFG/PR27615-simplify-cond-br.ll b/llvm/test/Transforms/SimplifyCFG/PR27615-simplify-cond-br.ll
@@ -1,5 +1,5 @@
-; RUN: opt -S -simplifycfg -strip-debug < %s | FileCheck %s
-; RUN: opt -S -simplifycfg < %s | FileCheck %s
+; RUN: opt -S -simplifycfg -simplifycfg-require-and-preserve-domtree=1 -strip-debug < %s | FileCheck %s
+; RUN: opt -S -simplifycfg -simplifycfg-require-and-preserve-domtree=1 < %s | FileCheck %s
 
 ; Test case for BUG-27615
 ; Test that simplify cond branch produce same result for debug and non-debug builds

diff --git a/llvm/test/Transforms/SimplifyCFG/PhiBlockMerge2.ll b/llvm/test/Transforms/SimplifyCFG/PhiBlockMerge2.ll
@@ -2,7 +2,7 @@
 ; where the mergedinto block doesn't have any PHI nodes, and is in fact
 ; dominated by the block-to-be-eliminated
 ;
-; RUN: opt < %s -simplifycfg -S | not grep N:
+; RUN: opt < %s -simplifycfg -simplifycfg-require-and-preserve-domtree=1 -S | not grep N:
 ;
 
 declare i1 @foo()

diff --git a/llvm/test/Transforms/SimplifyCFG/PhiEliminate.ll b/llvm/test/Transforms/SimplifyCFG/PhiEliminate.ll
@@ -3,7 +3,7 @@
 ; nodes away allows the branches to be eliminated, performing a simple form of
 ; 'if conversion'.
 
-; RUN: opt < %s -simplifycfg -S > %t.xform
+; RUN: opt < %s -simplifycfg -simplifycfg-require-and-preserve-domtree=1 -S > %t.xform
 ; RUN:   not grep phi %t.xform
 ; RUN:   grep ret %t.xform
 

diff --git a/llvm/test/Transforms/SimplifyCFG/PhiEliminate3.ll b/llvm/test/Transforms/SimplifyCFG/PhiEliminate3.ll
@@ -1,7 +1,7 @@
 ; NOTE: Assertions have been autogenerated by utils/update_test_checks.py
-; RUN: opt < %s -simplifycfg -S -phi-node-folding-threshold=1 | FileCheck %s
-; RUN: opt < %s -simplifycfg -S -phi-node-folding-threshold=2 | FileCheck %s
-; RUN: opt < %s -simplifycfg -S -phi-node-folding-threshold=7 | FileCheck %s
+; RUN: opt < %s -simplifycfg -simplifycfg-require-and-preserve-domtree=1 -S -phi-node-folding-threshold=1 | FileCheck %s
+; RUN: opt < %s -simplifycfg -simplifycfg-require-and-preserve-domtree=1 -S -phi-node-folding-threshold=2 | FileCheck %s
+; RUN: opt < %s -simplifycfg -simplifycfg-require-and-preserve-domtree=1 -S -phi-node-folding-threshold=7 | FileCheck %s
 
 ; Test merging of blocks containing complex expressions,
 ; with various folding thresholds

diff --git a/llvm/test/Transforms/SimplifyCFG/PhiNoEliminate.ll b/llvm/test/Transforms/SimplifyCFG/PhiNoEliminate.ll
@@ -1,4 +1,4 @@
-; RUN: opt < %s -simplifycfg -S | \
+; RUN: opt < %s -simplifycfg -simplifycfg-require-and-preserve-domtree=1 -S | \
 ; RUN:   not grep select
 
 ;; The PHI node in this example should not be turned into a select, as we are

diff --git a/llvm/test/Transforms/SimplifyCFG/PowerPC/cttz-ctlz-spec.ll b/llvm/test/Transforms/SimplifyCFG/PowerPC/cttz-ctlz-spec.ll
@@ -1,4 +1,4 @@
-; RUN: opt -S -simplifycfg < %s | FileCheck -enable-var-scope %s
+; RUN: opt -S -simplifycfg -simplifycfg-require-and-preserve-domtree=1 < %s | FileCheck -enable-var-scope %s
 target datalayout = "E-m:e-i64:64-n32:64"
 target triple = "powerpc64-unknown-linux-gnu"
 

diff --git a/llvm/test/Transforms/SimplifyCFG/PowerPC/prefer-fma.ll b/llvm/test/Transforms/SimplifyCFG/PowerPC/prefer-fma.ll
@@ -1,5 +1,5 @@
 ; NOTE: Assertions have been autogenerated by utils/update_test_checks.py
-; RUN: opt < %s -mtriple=powerpc64le-unknown-linux-gnu -simplifycfg -hoist-common-insts=true -enable-unsafe-fp-math -S | \
+; RUN: opt < %s -mtriple=powerpc64le-unknown-linux-gnu -simplifycfg -simplifycfg-require-and-preserve-domtree=1 -hoist-common-insts=true -enable-unsafe-fp-math -S | \
 ; RUN: FileCheck %s
 
 ; This case is copied from test/Transforms/SimplifyCFG/AArch64/

diff --git a/llvm/test/Transforms/SimplifyCFG/PowerPC/prefer-load-i32.ll b/llvm/test/Transforms/SimplifyCFG/PowerPC/prefer-load-i32.ll
@@ -1,4 +1,4 @@
-; RUN: opt < %s -mtriple=powerpc64le-unknown-linux-gnu -simplifycfg -hoist-common-insts=true -S | FileCheck %s
+; RUN: opt < %s -mtriple=powerpc64le-unknown-linux-gnu -simplifycfg -simplifycfg-require-and-preserve-domtree=1 -hoist-common-insts=true -S | FileCheck %s
 
 define float @foo(float* %src, float* %dest, i32 signext %count, i32 signext %cond) {
 ; CHECK-LABEL: @foo(

diff --git a/llvm/test/Transforms/SimplifyCFG/SPARC/switch_to_lookup_table.ll b/llvm/test/Transforms/SimplifyCFG/SPARC/switch_to_lookup_table.ll
@@ -1,4 +1,4 @@
-; RUN: opt < %s -simplifycfg -S -mtriple=sparc-unknown-unknown | FileCheck %s
+; RUN: opt < %s -simplifycfg -simplifycfg-require-and-preserve-domtree=1 -S -mtriple=sparc-unknown-unknown | FileCheck %s
 
 ; Check that switches are not turned into lookup tables, as this is not
 ; considered profitable on the target.

diff --git a/llvm/test/Transforms/SimplifyCFG/UncondBranchToHeader.ll b/llvm/test/Transforms/SimplifyCFG/UncondBranchToHeader.ll
@@ -1,4 +1,4 @@
-; RUN: opt < %s -simplifycfg -S | FileCheck %s
+; RUN: opt < %s -simplifycfg -simplifycfg-require-and-preserve-domtree=1 -S | FileCheck %s
 
 ; Check that we can get rid of empty block leading to header
 ; if it does not introduce new edge.

diff --git a/llvm/test/Transforms/SimplifyCFG/X86/combine-parallel-mem-md.ll b/llvm/test/Transforms/SimplifyCFG/X86/combine-parallel-mem-md.ll
@@ -1,4 +1,4 @@
-; RUN: opt -simplifycfg -S < %s | FileCheck %s
+; RUN: opt -simplifycfg -simplifycfg-require-and-preserve-domtree=1 -S < %s | FileCheck %s
 target datalayout = "e-m:e-i64:64-f80:128-n8:16:32:64-S128"
 target triple = "x86_64-unknown-linux-gnu"
 

diff --git a/llvm/test/Transforms/SimplifyCFG/X86/disable-lookup-table.ll b/llvm/test/Transforms/SimplifyCFG/X86/disable-lookup-table.ll
@@ -1,5 +1,5 @@
 ; NOTE: Assertions have been autogenerated by utils/update_test_checks.py
-; RUN: opt < %s -simplifycfg -switch-to-lookup -S -mtriple=x86_64-unknown-linux-gnu | FileCheck %s
+; RUN: opt < %s -simplifycfg -simplifycfg-require-and-preserve-domtree=1 -switch-to-lookup -S -mtriple=x86_64-unknown-linux-gnu | FileCheck %s
 ; RUN: opt < %s -passes='simplify-cfg<switch-to-lookup>' -S -mtriple=x86_64-unknown-linux-gnu | FileCheck %s
 
 ; In the presence of "-no-jump-tables"="true", simplifycfg should not convert switches to lookup tables.

diff --git a/llvm/test/Transforms/SimplifyCFG/X86/fold-branch-debuginvariant.ll b/llvm/test/Transforms/SimplifyCFG/X86/fold-branch-debuginvariant.ll
@@ -1,5 +1,5 @@
-; RUN: opt < %s -simplifycfg -S | FileCheck %s
-; RUN: opt < %s -strip-debug -simplifycfg -S | FileCheck %s
+; RUN: opt < %s -simplifycfg -simplifycfg-require-and-preserve-domtree=1 -S | FileCheck %s
+; RUN: opt < %s -strip-debug -simplifycfg -simplifycfg-require-and-preserve-domtree=1 -S | FileCheck %s
 
 ; Verify that the and.2 instruction is eliminated even in the presence of a
 ; preceding debug intrinsic.

diff --git a/llvm/test/Transforms/SimplifyCFG/X86/merge-cleanuppads.ll b/llvm/test/Transforms/SimplifyCFG/X86/merge-cleanuppads.ll
@@ -1,4 +1,4 @@
-; RUN: opt -S -simplifycfg < %s | FileCheck %s
+; RUN: opt -S -simplifycfg -simplifycfg-require-and-preserve-domtree=1 < %s | FileCheck %s
 target datalayout = "e-m:w-i64:64-f80:128-n8:16:32:64-S128"
 target triple = "x86_64-pc-windows-msvc18.0.0"
 

diff --git a/llvm/test/Transforms/SimplifyCFG/X86/merge-cond-stores-cost.ll b/llvm/test/Transforms/SimplifyCFG/X86/merge-cond-stores-cost.ll
@@ -1,5 +1,5 @@
 ; NOTE: Assertions have been autogenerated by utils/update_test_checks.py
-; RUN: opt -simplifycfg -mtriple=x86_64-unknown-unknown < %s -simplifycfg-merge-cond-stores=true -simplifycfg-merge-cond-stores-aggressively=false -phi-node-folding-threshold=2 -S | FileCheck %s
+; RUN: opt -simplifycfg -simplifycfg-require-and-preserve-domtree=1 -mtriple=x86_64-unknown-unknown < %s -simplifycfg-merge-cond-stores=true -simplifycfg-merge-cond-stores-aggressively=false -phi-node-folding-threshold=2 -S | FileCheck %s
 
 define void @test_costly(i32* %p, i32 %a, i32 %b, i32 %c, i32 %d) {
 ; CHECK-LABEL: @test_costly(

diff --git a/llvm/test/Transforms/SimplifyCFG/X86/remove-debug-2.ll b/llvm/test/Transforms/SimplifyCFG/X86/remove-debug-2.ll
@@ -1,4 +1,4 @@
-; RUN: opt < %s -simplifycfg -S | FileCheck %s
+; RUN: opt < %s -simplifycfg -simplifycfg-require-and-preserve-domtree=1 -S | FileCheck %s
 
 ; Check that the debug location for the hoisted store for "ret = 0" is a
 ; line-0 location.

diff --git a/llvm/test/Transforms/SimplifyCFG/X86/remove-debug.ll b/llvm/test/Transforms/SimplifyCFG/X86/remove-debug.ll
@@ -1,4 +1,4 @@
-; RUN: opt < %s -simplifycfg -S -hoist-common-insts=true | FileCheck %s
+; RUN: opt < %s -simplifycfg -simplifycfg-require-and-preserve-domtree=1 -S -hoist-common-insts=true | FileCheck %s
 
 ; TODO: Track the acutal DebugLoc of the hoisted instruction when no-line
 ; DebugLoc is supported (https://reviews.llvm.org/D24180)

diff --git a/llvm/test/Transforms/SimplifyCFG/X86/unreachable-blocks.ll b/llvm/test/Transforms/SimplifyCFG/X86/unreachable-blocks.ll
@@ -1,4 +1,4 @@
-; RUN: opt -simplifycfg < %s -disable-output
+; RUN: opt -simplifycfg -simplifycfg-require-and-preserve-domtree=1 < %s -disable-output
 
 target datalayout = "e-p:64:64:64-i1:8:8-i8:8:8-i16:16:16-i32:32:32-i64:64:64-f32:32:32-f64:64:64-v64:64:64-v128:128:128-a0:0:64-s0:64:64-f80:128:128-n8:16:32:64"
 target triple = "x86_64-pc-linux-gnu"

diff --git a/llvm/test/Transforms/SimplifyCFG/assume.ll b/llvm/test/Transforms/SimplifyCFG/assume.ll
@@ -1,4 +1,4 @@
-; RUN: opt -simplifycfg -S < %s | FileCheck %s
+; RUN: opt -simplifycfg -simplifycfg-require-and-preserve-domtree=1 -S < %s | FileCheck %s
 
 define void @test1() {
         call void @llvm.assume(i1 0)

diff --git a/llvm/test/Transforms/SimplifyCFG/attr-convergent.ll b/llvm/test/Transforms/SimplifyCFG/attr-convergent.ll
@@ -1,4 +1,4 @@
-; RUN: opt < %s -simplifycfg -S | FileCheck %s
+; RUN: opt < %s -simplifycfg -simplifycfg-require-and-preserve-domtree=1 -S | FileCheck %s
 
 ; Checks that the SimplifyCFG pass won't duplicate a call to a function marked
 ; convergent.

diff --git a/llvm/test/Transforms/SimplifyCFG/attr-noduplicate.ll b/llvm/test/Transforms/SimplifyCFG/attr-noduplicate.ll
@@ -1,4 +1,4 @@
-; RUN: opt < %s -simplifycfg -S | FileCheck %s
+; RUN: opt < %s -simplifycfg -simplifycfg-require-and-preserve-domtree=1 -S | FileCheck %s
 
 ; This test checks that the SimplifyCFG pass won't duplicate a call to a
 ; function marked noduplicate.

diff --git a/llvm/test/Transforms/SimplifyCFG/branch-cond-merge.ll b/llvm/test/Transforms/SimplifyCFG/branch-cond-merge.ll
@@ -1,5 +1,5 @@
-; RUN: opt < %s -simplifycfg -instcombine \
-; RUN:   -simplifycfg -S | not grep call
+; RUN: opt < %s -simplifycfg -simplifycfg-require-and-preserve-domtree=1 -instcombine \
+; RUN:   -simplifycfg -simplifycfg-require-and-preserve-domtree=1 -S | not grep call
 
 declare void @bar()
 

diff --git a/llvm/test/Transforms/SimplifyCFG/branch-cond-prop.ll b/llvm/test/Transforms/SimplifyCFG/branch-cond-prop.ll
@@ -1,4 +1,4 @@
-; RUN: opt < %s -simplifycfg -S | not grep call
+; RUN: opt < %s -simplifycfg -simplifycfg-require-and-preserve-domtree=1 -S | not grep call
 
 declare void @bar()
 

diff --git a/llvm/test/Transforms/SimplifyCFG/branch-fold-test.ll b/llvm/test/Transforms/SimplifyCFG/branch-fold-test.ll
@@ -1,7 +1,7 @@
 ; This test ensures that the simplifycfg pass continues to constant fold
 ; terminator instructions.
 
-; RUN: opt < %s -simplifycfg -S | not grep br
+; RUN: opt < %s -simplifycfg -simplifycfg-require-and-preserve-domtree=1 -S | not grep br
 
 define i32 @test(i32 %A, i32 %B) {
 J:

diff --git a/llvm/test/Transforms/SimplifyCFG/branch-fold-three.ll b/llvm/test/Transforms/SimplifyCFG/branch-fold-three.ll
@@ -1,5 +1,5 @@
 ; NOTE: Assertions have been autogenerated by utils/update_test_checks.py
-; RUN: opt < %s -simplifycfg -S | FileCheck %s
+; RUN: opt < %s -simplifycfg -simplifycfg-require-and-preserve-domtree=1 -S | FileCheck %s
 
 ; s >= t, s != t, s <= t
 define void @foo1(i32 %s, i32 %t) {

diff --git a/llvm/test/Transforms/SimplifyCFG/branch-phi-thread.ll b/llvm/test/Transforms/SimplifyCFG/branch-phi-thread.ll
@@ -1,4 +1,4 @@
-; RUN: opt < %s -simplifycfg -adce -S | \
+; RUN: opt < %s -simplifycfg -simplifycfg-require-and-preserve-domtree=1 -adce -S | \
 ; RUN:   not grep "call void @f1"
 ; END.
 

diff --git a/llvm/test/Transforms/SimplifyCFG/callbr-destinations.ll b/llvm/test/Transforms/SimplifyCFG/callbr-destinations.ll
@@ -1,4 +1,4 @@
-; RUN: opt < %s -simplifycfg -disable-output
+; RUN: opt < %s -simplifycfg -simplifycfg-require-and-preserve-domtree=1 -disable-output
 ;
 ; Test that SimplifyCFG does not cause CallBr instructions to have duplicate
 ; destinations, which will cause the verifier to assert.

diff --git a/llvm/test/Transforms/SimplifyCFG/common-code-hoisting.ll b/llvm/test/Transforms/SimplifyCFG/common-code-hoisting.ll
@@ -1,7 +1,7 @@
 ; NOTE: Assertions have been autogenerated by utils/update_test_checks.py
-; RUN: opt -simplifycfg -hoist-common-insts=1 -S < %s                    | FileCheck %s --check-prefix=HOIST
-; RUN: opt -simplifycfg -hoist-common-insts=0 -S < %s                    | FileCheck %s --check-prefix=NOHOIST
-; RUN: opt -simplifycfg                       -S < %s                    | FileCheck %s --check-prefix=NOHOIST
+; RUN: opt -simplifycfg -simplifycfg-require-and-preserve-domtree=1 -hoist-common-insts=1 -S < %s                    | FileCheck %s --check-prefix=HOIST
+; RUN: opt -simplifycfg -simplifycfg-require-and-preserve-domtree=1 -hoist-common-insts=0 -S < %s                    | FileCheck %s --check-prefix=NOHOIST
+; RUN: opt -simplifycfg -simplifycfg-require-and-preserve-domtree=1                       -S < %s                    | FileCheck %s --check-prefix=NOHOIST
 
 ; This example is produced from a very basic C code:
 ;

diff --git a/llvm/test/Transforms/SimplifyCFG/constantexprs.ll b/llvm/test/Transforms/SimplifyCFG/constantexprs.ll
@@ -1,4 +1,4 @@
-; RUN: opt -simplifycfg -S < %s | FileCheck %s
+; RUN: opt -simplifycfg -simplifycfg-require-and-preserve-domtree=1 -S < %s | FileCheck %s
 
 ; See that we do not crash when queriying cost model about the cost of constant expression extractelement.
 

diff --git a/llvm/test/Transforms/SimplifyCFG/convergent.ll b/llvm/test/Transforms/SimplifyCFG/convergent.ll
@@ -1,5 +1,5 @@
 ; NOTE: Assertions have been autogenerated by utils/update_test_checks.py
-; RUN: opt -S -simplifycfg < %s | FileCheck %s
+; RUN: opt -S -simplifycfg -simplifycfg-require-and-preserve-domtree=1 < %s | FileCheck %s
 ; RUN: opt -S -passes=simplify-cfg < %s | FileCheck %s
 
 declare void @foo() convergent

diff --git a/llvm/test/Transforms/SimplifyCFG/dbginfo.ll b/llvm/test/Transforms/SimplifyCFG/dbginfo.ll
@@ -1,4 +1,4 @@
-; RUN: opt < %s -simplifycfg -S | not grep "br label"
+; RUN: opt < %s -simplifycfg -simplifycfg-require-and-preserve-domtree=1 -S | not grep "br label"
 
 	%llvm.dbg.anchor.type = type { i32, i32 }
 	%llvm.dbg.basictype.type = type { i32, { }*, i8*, { }*, i32, i64, i64, i64, i32, i32 }

diff --git a/llvm/test/Transforms/SimplifyCFG/dce-cond-after-folding-terminator.ll b/llvm/test/Transforms/SimplifyCFG/dce-cond-after-folding-terminator.ll
@@ -1,4 +1,4 @@
-; RUN: opt -S <%s -simplifycfg | FileCheck %s
+; RUN: opt -S <%s -simplifycfg -simplifycfg-require-and-preserve-domtree=1 | FileCheck %s
 
 define void @test_br(i32 %x) {
 entry:

diff --git a/llvm/test/Transforms/SimplifyCFG/debug-info-thread-phi.ll b/llvm/test/Transforms/SimplifyCFG/debug-info-thread-phi.ll
@@ -1,4 +1,4 @@
-; RUN: opt %s -debugify -simplifycfg -S | FileCheck %s
+; RUN: opt %s -debugify -simplifycfg -simplifycfg-require-and-preserve-domtree=1 -S | FileCheck %s
 ; Tests Bug 37966
 
 define void @bar(i32 %aa) {

diff --git a/llvm/test/Transforms/SimplifyCFG/div-rem-pairs.ll b/llvm/test/Transforms/SimplifyCFG/div-rem-pairs.ll
@@ -1,4 +1,4 @@
-; RUN: opt -simplifycfg -S < %s | FileCheck %s
+; RUN: opt -simplifycfg -simplifycfg-require-and-preserve-domtree=1 -S < %s | FileCheck %s
 
 ; We could hoist the div/rem in these tests because it's safe to do so.
 ; PR31028 - https://bugs.llvm.org/show_bug.cgi?id=31028

diff --git a/llvm/test/Transforms/SimplifyCFG/drop-debug-loc-when-speculating.ll b/llvm/test/Transforms/SimplifyCFG/drop-debug-loc-when-speculating.ll
@@ -1,4 +1,4 @@
-; RUN: opt -S -o - %s -simplifycfg | FileCheck %s
+; RUN: opt -S -o - %s -simplifycfg -simplifycfg-require-and-preserve-domtree=1 | FileCheck %s
 
 declare i1 @make_condition()
 

diff --git a/llvm/test/Transforms/SimplifyCFG/duplicate-landingpad.ll b/llvm/test/Transforms/SimplifyCFG/duplicate-landingpad.ll
@@ -1,5 +1,5 @@
 ; NOTE: Assertions have been autogenerated by utils/update_test_checks.py
-; RUN: opt < %s -simplifycfg -S | FileCheck %s
+; RUN: opt < %s -simplifycfg -simplifycfg-require-and-preserve-domtree=1 -S | FileCheck %s
 target datalayout = "e-p:64:64:64-i1:8:8-i8:8:8-i16:16:16-i32:32:32-i64:64:64-f32:32:32-f64:64:64-v64:64:64-v128:128:128-a0:0:64-s0:64:64-f80:128:128-n8:16:32:64-S128"
 
 declare i32 @__gxx_personality_v0(...)

diff --git a/llvm/test/Transforms/SimplifyCFG/duplicate-phis.ll b/llvm/test/Transforms/SimplifyCFG/duplicate-phis.ll
@@ -1,4 +1,4 @@
-; RUN: opt < %s -instcombine -simplifycfg -S | grep " = phi " | count 1
+; RUN: opt < %s -instcombine -simplifycfg -simplifycfg-require-and-preserve-domtree=1 -S | grep " = phi " | count 1
 
 ; instcombine should sort the PHI operands so that simplifycfg can see the
 ; duplicate and remove it.

diff --git a/llvm/test/Transforms/SimplifyCFG/extract-cost.ll b/llvm/test/Transforms/SimplifyCFG/extract-cost.ll
@@ -1,5 +1,5 @@
 ; NOTE: Assertions have been autogenerated by utils/update_test_checks.py
-; RUN: opt -simplifycfg -S  < %s | FileCheck %s
+; RUN: opt -simplifycfg -simplifycfg-require-and-preserve-domtree=1 -S  < %s | FileCheck %s
 
 declare { i32, i1 } @llvm.uadd.with.overflow.i32(i32, i32) #1
 

diff --git a/llvm/test/Transforms/SimplifyCFG/gepcost.ll b/llvm/test/Transforms/SimplifyCFG/gepcost.ll
@@ -1,5 +1,5 @@
 ; NOTE: Assertions have been autogenerated by utils/update_test_checks.py
-; RUN: opt < %s -S -simplifycfg | FileCheck %s
+; RUN: opt < %s -S -simplifycfg -simplifycfg-require-and-preserve-domtree=1 | FileCheck %s
 
 target datalayout = "e-m:e-p:32:32-i64:64-v128:64:128-a:0:32-n32-S64"
 target triple = "thumbv7m-none--eabi"

diff --git a/llvm/test/Transforms/SimplifyCFG/guards.ll b/llvm/test/Transforms/SimplifyCFG/guards.ll
@@ -1,5 +1,5 @@
 ; NOTE: Assertions have been autogenerated by utils/update_test_checks.py
-; RUN: opt -S -simplifycfg < %s | FileCheck %s
+; RUN: opt -S -simplifycfg -simplifycfg-require-and-preserve-domtree=1 < %s | FileCheck %s
 
 declare void @llvm.experimental.guard(i1, ...)
 

diff --git a/llvm/test/Transforms/SimplifyCFG/hoist-dbgvalue.ll b/llvm/test/Transforms/SimplifyCFG/hoist-dbgvalue.ll
@@ -1,4 +1,4 @@
-; RUN: opt -simplifycfg -S < %s | FileCheck %s
+; RUN: opt -simplifycfg -simplifycfg-require-and-preserve-domtree=1 -S < %s | FileCheck %s
 
 define i32 @foo(i32 %i) nounwind ssp !dbg !0 {
   call void @llvm.dbg.value(metadata i32 %i, metadata !6, metadata !DIExpression()), !dbg !7

diff --git a/llvm/test/Transforms/SimplifyCFG/implied-and-or.ll b/llvm/test/Transforms/SimplifyCFG/implied-and-or.ll
@@ -1,5 +1,5 @@
 ; NOTE: Assertions have been autogenerated by utils/update_test_checks.py
-; RUN: opt < %s -S -simplifycfg | FileCheck %s
+; RUN: opt < %s -S -simplifycfg -simplifycfg-require-and-preserve-domtree=1 | FileCheck %s
 
 declare void @foo()
 declare void @bar()

diff --git a/llvm/test/Transforms/SimplifyCFG/inline-asm-sink.ll b/llvm/test/Transforms/SimplifyCFG/inline-asm-sink.ll
@@ -1,4 +1,4 @@
-; RUN: opt < %s -mem2reg -simplifycfg -S | FileCheck -enable-var-scope %s
+; RUN: opt < %s -mem2reg -simplifycfg -simplifycfg-require-and-preserve-domtree=1 -S | FileCheck -enable-var-scope %s
 
 define i32 @test(i32 %x) {
 ; CHECK-LABEL: @test

diff --git a/llvm/test/Transforms/SimplifyCFG/invoke.ll b/llvm/test/Transforms/SimplifyCFG/invoke.ll
@@ -1,4 +1,4 @@
-; RUN: opt < %s -simplifycfg -S | FileCheck %s
+; RUN: opt < %s -simplifycfg -simplifycfg-require-and-preserve-domtree=1 -S | FileCheck %s
 target datalayout = "e-p:64:64:64-i1:8:8-i8:8:8-i16:16:16-i32:32:32-i64:64:64-f32:32:32-f64:64:64-v64:64:64-v128:128:128-a0:0:64-s0:64:64-f80:128:128-n8:16:32:64-S128"
 
 declare i32 @__gxx_personality_v0(...)

diff --git a/llvm/test/Transforms/SimplifyCFG/lifetime.ll b/llvm/test/Transforms/SimplifyCFG/lifetime.ll
@@ -1,4 +1,4 @@
-; RUN: opt < %s -simplifycfg -S | FileCheck %s
+; RUN: opt < %s -simplifycfg -simplifycfg-require-and-preserve-domtree=1 -S | FileCheck %s
 
 ; Test that a lifetime intrinsic isn't removed because that would change semantics
 

diff --git a/llvm/test/Transforms/SimplifyCFG/merge-default.ll b/llvm/test/Transforms/SimplifyCFG/merge-default.ll
@@ -1,4 +1,4 @@
-; RUN: opt -simplifycfg -S < %s | FileCheck %s
+; RUN: opt -simplifycfg -simplifycfg-require-and-preserve-domtree=1 -S < %s | FileCheck %s
 
 target datalayout = "e-m:e-p270:32:32-p271:32:32-p272:64:64-i64:64-f80:128-n8:16:32:64-S128"
 target triple = "x86_64-unknown-linux-gnu"

diff --git a/llvm/test/Transforms/SimplifyCFG/merge-empty-return-blocks.ll b/llvm/test/Transforms/SimplifyCFG/merge-empty-return-blocks.ll
@@ -0,0 +1,48 @@
+; NOTE: Assertions have been autogenerated by utils/update_test_checks.py
+; RUN: opt -simplifycfg -simplifycfg-require-and-preserve-domtree=1 -S < %s | FileCheck %s
+
+define void @t0(i1 %c) {
+; CHECK-LABEL: @t0(
+; CHECK-NEXT:  entry:
+; CHECK-NEXT:    ret void
+;
+entry:
+  br i1 %c, label %end0, label %end1
+
+end0:
+  ret void
+
+end1:
+  ret void
+}
+
+define i8 @t1(i1 %c, i8 %v) {
+; CHECK-LABEL: @t1(
+; CHECK-NEXT:  entry:
+; CHECK-NEXT:    ret i8 [[V:%.*]]
+;
+entry:
+  br i1 %c, label %end0, label %end1
+
+end0:
+  ret i8 %v
+
+end1:
+  ret i8 %v
+}
+
+define i8 @t2(i1 %c, i8 %v0, i8 %v1) {
+; CHECK-LABEL: @t2(
+; CHECK-NEXT:  entry:
+; CHECK-NEXT:    [[SPEC_SELECT:%.*]] = select i1 [[C:%.*]], i8 [[V0:%.*]], i8 [[V1:%.*]]
+; CHECK-NEXT:    ret i8 [[SPEC_SELECT]]
+;
+entry:
+  br i1 %c, label %end0, label %end1
+
+end0:
+  ret i8 %v0
+
+end1:
+  ret i8 %v1
+}
diff --git a/llvm/test/Transforms/SimplifyCFG/multiple-phis.ll b/llvm/test/Transforms/SimplifyCFG/multiple-phis.ll
@@ -1,5 +1,5 @@
 ; NOTE: Assertions have been autogenerated by utils/update_test_checks.py
-; RUN: opt -simplifycfg -keep-loops=false -S < %s | FileCheck %s
+; RUN: opt -simplifycfg -simplifycfg-require-and-preserve-domtree=1 -keep-loops=false -S < %s | FileCheck %s
 ; RUN: opt -passes='simplify-cfg<no-keep-loops>' -S < %s | FileCheck %s
 
 ; It's not worthwhile to if-convert one of the phi nodes and leave

diff --git a/llvm/test/Transforms/SimplifyCFG/no_speculative_loads_with_asan.ll b/llvm/test/Transforms/SimplifyCFG/no_speculative_loads_with_asan.ll
@@ -1,4 +1,4 @@
-; RUN: opt -simplifycfg -S %s | FileCheck %s
+; RUN: opt -simplifycfg -simplifycfg-require-and-preserve-domtree=1 -S %s | FileCheck %s
 ; Make sure we don't speculate loads under AddressSanitizer.
 @g = global i32 0, align 4
 

diff --git a/llvm/test/Transforms/SimplifyCFG/no_speculative_loads_with_tsan.ll b/llvm/test/Transforms/SimplifyCFG/no_speculative_loads_with_tsan.ll
@@ -1,4 +1,4 @@
-; RUN: opt -simplifycfg -S %s | FileCheck %s
+; RUN: opt -simplifycfg -simplifycfg-require-and-preserve-domtree=1 -S %s | FileCheck %s
 ; Make sure we don't speculate loads under ThreadSanitizer.
 @g = global i32 0, align 4
 

diff --git a/llvm/test/Transforms/SimplifyCFG/noreturn-call.ll b/llvm/test/Transforms/SimplifyCFG/noreturn-call.ll
@@ -1,4 +1,4 @@
-; RUN: opt < %s -simplifycfg -S | FileCheck %s
+; RUN: opt < %s -simplifycfg -simplifycfg-require-and-preserve-domtree=1 -S | FileCheck %s
 ; PR1796
 
 declare void @Finisher(i32) noreturn

diff --git a/llvm/test/Transforms/SimplifyCFG/phi-to-select-constexpr-icmp.ll b/llvm/test/Transforms/SimplifyCFG/phi-to-select-constexpr-icmp.ll
@@ -1,5 +1,5 @@
 ; NOTE: Assertions have been autogenerated by utils/update_test_checks.py
-; RUN: opt -simplifycfg -S %s | FileCheck %s
+; RUN: opt -simplifycfg -simplifycfg-require-and-preserve-domtree=1 -S %s | FileCheck %s
 
 @glob = internal constant [5 x i8*] zeroinitializer, align 16
 

diff --git a/llvm/test/Transforms/SimplifyCFG/phi-undef-loadstore.ll b/llvm/test/Transforms/SimplifyCFG/phi-undef-loadstore.ll
@@ -1,4 +1,4 @@
-; RUN: opt -simplifycfg -S < %s | FileCheck %s
+; RUN: opt -simplifycfg -simplifycfg-require-and-preserve-domtree=1 -S < %s | FileCheck %s
 
 declare void @bar() nounwind
 

diff --git a/llvm/test/Transforms/SimplifyCFG/pr33605.ll b/llvm/test/Transforms/SimplifyCFG/pr33605.ll
@@ -1,4 +1,4 @@
-; RUN: opt < %s -simplifycfg -S | FileCheck %s
+; RUN: opt < %s -simplifycfg -simplifycfg-require-and-preserve-domtree=1 -S | FileCheck %s
 
 ; Skip simplifying unconditional branches from empty blocks in simplifyCFG,
 ; when it can destroy canonical loop structure.

diff --git a/llvm/test/Transforms/SimplifyCFG/pr35774.ll b/llvm/test/Transforms/SimplifyCFG/pr35774.ll
@@ -1,5 +1,5 @@
 ; NOTE: Assertions have been autogenerated by utils/update_test_checks.py
-; RUN: opt -simplifycfg -S %s | FileCheck %s
+; RUN: opt -simplifycfg -simplifycfg-require-and-preserve-domtree=1 -S %s | FileCheck %s
 
 %foo = type { i32 (%foo)*, i32 }
 

diff --git a/llvm/test/Transforms/SimplifyCFG/pr46638.ll b/llvm/test/Transforms/SimplifyCFG/pr46638.ll
@@ -1,5 +1,5 @@
 ; NOTE: Assertions have been autogenerated by utils/update_test_checks.py
-; RUN: opt -S -simplifycfg < %s | FileCheck %s
+; RUN: opt -S -simplifycfg -simplifycfg-require-and-preserve-domtree=1 < %s | FileCheck %s
 
 define void @pr46638(i1 %c, i32 %x) {
 ; CHECK-LABEL: @pr46638(

diff --git a/llvm/test/Transforms/SimplifyCFG/preserve-branchweights-partial.ll b/llvm/test/Transforms/SimplifyCFG/preserve-branchweights-partial.ll
@@ -1,8 +1,8 @@
-; RUN: opt -simplifycfg -S -o - < %s | FileCheck %s
+; RUN: opt -simplifycfg -simplifycfg-require-and-preserve-domtree=1 -S -o - < %s | FileCheck %s
 
 ; This test case was written to trigger an incorrect assert statement in
 ; -simplifycfg.  Thus we don't actually want to check the output, just that
-; -simplifycfg ran successfully.  Thus we only check that the function still
+; -simplifycfg -simplifycfg-require-and-preserve-domtree=1 ran successfully.  Thus we only check that the function still
 ; exists, and that it still calls foo().
 ;
 ; NOTE: There are some obviously dead blocks and missing branch weight

diff --git a/llvm/test/Transforms/SimplifyCFG/preserve-llvm-loop-metadata.ll b/llvm/test/Transforms/SimplifyCFG/preserve-llvm-loop-metadata.ll
@@ -1,4 +1,4 @@
-; RUN: opt -simplifycfg -keep-loops=false -S < %s | FileCheck %s
+; RUN: opt -simplifycfg -simplifycfg-require-and-preserve-domtree=1 -keep-loops=false -S < %s | FileCheck %s
 ; RUN: opt -passes='simplify-cfg<no-keep-loops>' -S < %s | FileCheck %s
 
 define void @test1(i32 %n) #0 {

diff --git a/llvm/test/Transforms/SimplifyCFG/preserve-load-metadata-2.ll b/llvm/test/Transforms/SimplifyCFG/preserve-load-metadata-2.ll
@@ -1,4 +1,4 @@
-; RUN: opt < %s -simplifycfg -hoist-common-insts=true -S | FileCheck %s
+; RUN: opt < %s -simplifycfg -simplifycfg-require-and-preserve-domtree=1 -hoist-common-insts=true -S | FileCheck %s
 
 declare void @bar(i32*)
 declare void @baz(i32*)

diff --git a/llvm/test/Transforms/SimplifyCFG/preserve-load-metadata-3.ll b/llvm/test/Transforms/SimplifyCFG/preserve-load-metadata-3.ll
@@ -1,4 +1,4 @@
-; RUN: opt < %s -simplifycfg -hoist-common-insts=true -S | FileCheck %s
+; RUN: opt < %s -simplifycfg -simplifycfg-require-and-preserve-domtree=1 -hoist-common-insts=true -S | FileCheck %s
 
 declare void @bar(i32*)
 declare void @baz(i32*)

diff --git a/llvm/test/Transforms/SimplifyCFG/preserve-load-metadata.ll b/llvm/test/Transforms/SimplifyCFG/preserve-load-metadata.ll
@@ -1,4 +1,4 @@
-; RUN: opt < %s -simplifycfg -hoist-common-insts=true -S | FileCheck %s
+; RUN: opt < %s -simplifycfg -simplifycfg-require-and-preserve-domtree=1 -hoist-common-insts=true -S | FileCheck %s
 
 declare void @bar(i32*)
 declare void @baz(i32*)

diff --git a/llvm/test/Transforms/SimplifyCFG/preserve-make-implicit-on-switch-to-br.ll b/llvm/test/Transforms/SimplifyCFG/preserve-make-implicit-on-switch-to-br.ll
@@ -1,4 +1,4 @@
-; RUN: opt %s -simplifycfg -S | FileCheck %s
+; RUN: opt %s -simplifycfg -simplifycfg-require-and-preserve-domtree=1 -S | FileCheck %s
 
 ; ConstantFoldTerminator function can convert SwitchInst with one case (and default) to
 ; a conditional BranchInst. This test checks the converted BranchInst preserve the

diff --git a/llvm/test/Transforms/SimplifyCFG/return-merge.ll b/llvm/test/Transforms/SimplifyCFG/return-merge.ll
@@ -1,4 +1,4 @@
-; RUN: opt < %s -simplifycfg -S | not grep br
+; RUN: opt < %s -simplifycfg -simplifycfg-require-and-preserve-domtree=1 -S | not grep br
 
 define i32 @test1(i1 %C) {
 entry:

diff --git a/llvm/test/Transforms/SimplifyCFG/seh-nounwind.ll b/llvm/test/Transforms/SimplifyCFG/seh-nounwind.ll
@@ -1,4 +1,4 @@
-; RUN: opt -S -simplifycfg < %s | FileCheck %s
+; RUN: opt -S -simplifycfg -simplifycfg-require-and-preserve-domtree=1 < %s | FileCheck %s
 
 ; Don't remove invokes of nounwind functions if the personality handles async
 ; exceptions. The @div function in this test can fault, even though it can't

diff --git a/llvm/test/Transforms/SimplifyCFG/select-gep.ll b/llvm/test/Transforms/SimplifyCFG/select-gep.ll
@@ -1,5 +1,5 @@
 ; NOTE: Assertions have been autogenerated by utils/update_test_checks.py
-; RUN: opt -S -simplifycfg < %s | FileCheck %s
+; RUN: opt -S -simplifycfg -simplifycfg-require-and-preserve-domtree=1 < %s | FileCheck %s
 
 %ST = type { i8, i8 }
 

diff --git a/llvm/test/Transforms/SimplifyCFG/speculate-call.ll b/llvm/test/Transforms/SimplifyCFG/speculate-call.ll
@@ -1,4 +1,4 @@
-; RUN: opt -S -simplifycfg < %s | FileCheck %s
+; RUN: opt -S -simplifycfg -simplifycfg-require-and-preserve-domtree=1 < %s | FileCheck %s
 
 ; CHECK-LABEL: @speculatable_attribute
 ; CHECK: select

diff --git a/llvm/test/Transforms/SimplifyCFG/speculate-dbgvalue.ll b/llvm/test/Transforms/SimplifyCFG/speculate-dbgvalue.ll
@@ -1,5 +1,5 @@
 ; NOTE: Assertions have been autogenerated by utils/update_test_checks.py
-; RUN: opt < %s -S -simplifycfg | FileCheck %s
+; RUN: opt < %s -S -simplifycfg -simplifycfg-require-and-preserve-domtree=1 | FileCheck %s
 
 ; This test case was generated from speculate-dbgvalue.c:
 ;

diff --git a/llvm/test/Transforms/SimplifyCFG/speculate-store.ll b/llvm/test/Transforms/SimplifyCFG/speculate-store.ll
@@ -1,4 +1,4 @@
-; RUN: opt -simplifycfg -S < %s | FileCheck %s
+; RUN: opt -simplifycfg -simplifycfg-require-and-preserve-domtree=1 -S < %s | FileCheck %s
 
 define void @ifconvertstore(i32* %A, i32 %B, i32 %C, i32 %D) {
 ; CHECK-LABEL: @ifconvertstore(

diff --git a/llvm/test/Transforms/SimplifyCFG/speculate-vector-ops.ll b/llvm/test/Transforms/SimplifyCFG/speculate-vector-ops.ll
@@ -1,4 +1,4 @@
-; RUN: opt -S -simplifycfg < %s | FileCheck %s
+; RUN: opt -S -simplifycfg -simplifycfg-require-and-preserve-domtree=1 < %s | FileCheck %s
 
 define i32 @speculate_vector_extract(i32 %d, <4 x i32> %v) #0 {
 ; CHECK-LABEL: @speculate_vector_extract(

diff --git a/llvm/test/Transforms/SimplifyCFG/statepoint-invoke-unwind.ll b/llvm/test/Transforms/SimplifyCFG/statepoint-invoke-unwind.ll
@@ -1,4 +1,4 @@
-; RUN: opt < %s -simplifycfg -S | FileCheck %s
+; RUN: opt < %s -simplifycfg -simplifycfg-require-and-preserve-domtree=1 -S | FileCheck %s
 ; Test that statepoint intrinsic is marked with Throwable attribute and it is
 ; not optimized into call
 

diff --git a/llvm/test/Transforms/SimplifyCFG/suppress-zero-branch-weights.ll b/llvm/test/Transforms/SimplifyCFG/suppress-zero-branch-weights.ll
@@ -1,4 +1,4 @@
-; RUN: opt -S -simplifycfg < %s | FileCheck %s
+; RUN: opt -S -simplifycfg -simplifycfg-require-and-preserve-domtree=1 < %s | FileCheck %s
 
 ; We're sign extending an 8-bit value.
 ; The switch condition must be in the range [-128, 127], so any cases outside of that range must be dead.

diff --git a/llvm/test/Transforms/SimplifyCFG/switch-to-br.ll b/llvm/test/Transforms/SimplifyCFG/switch-to-br.ll
@@ -1,4 +1,4 @@
-; RUN: opt %s -simplifycfg -S | FileCheck %s
+; RUN: opt %s -simplifycfg -simplifycfg-require-and-preserve-domtree=1 -S | FileCheck %s
 
 declare i32 @f(i32)
 

diff --git a/llvm/test/Transforms/SimplifyCFG/switch-to-select-multiple-edge-per-block-phi.ll b/llvm/test/Transforms/SimplifyCFG/switch-to-select-multiple-edge-per-block-phi.ll
@@ -1,4 +1,4 @@
-; RUN: opt < %s -simplifycfg -S | FileCheck %s
+; RUN: opt < %s -simplifycfg -simplifycfg-require-and-preserve-domtree=1 -S | FileCheck %s
 
 ; a, b;
 ; fn1() {

diff --git a/llvm/test/Transforms/SimplifyCFG/switch_undef.ll b/llvm/test/Transforms/SimplifyCFG/switch_undef.ll
@@ -1,5 +1,5 @@
 ; NOTE: Assertions have been autogenerated by utils/update_test_checks.py
-; RUN: opt %s -keep-loops=false -switch-to-lookup=true -simplifycfg -S | FileCheck %s
+; RUN: opt %s -keep-loops=false -switch-to-lookup=true -simplifycfg -simplifycfg-require-and-preserve-domtree=1 -S | FileCheck %s
 ; RUN: opt %s -passes='simplify-cfg<no-keep-loops;switch-to-lookup>' -S | FileCheck %s
 
 define void @f6() #0 {

diff --git a/llvm/test/Transforms/SimplifyCFG/trap-debugloc.ll b/llvm/test/Transforms/SimplifyCFG/trap-debugloc.ll
@@ -1,4 +1,4 @@
-; RUN: opt -S -simplifycfg < %s | FileCheck %s
+; RUN: opt -S -simplifycfg -simplifycfg-require-and-preserve-domtree=1 < %s | FileCheck %s
 ; Radar 9342286
 ; Assign DebugLoc to trap instruction.
 define void @foo() nounwind ssp !dbg !0 {

diff --git a/llvm/test/Transforms/SimplifyCFG/trap-no-null-opt-debugloc.ll b/llvm/test/Transforms/SimplifyCFG/trap-no-null-opt-debugloc.ll
@@ -1,4 +1,4 @@
-; RUN: opt -S -simplifycfg < %s | FileCheck %s
+; RUN: opt -S -simplifycfg -simplifycfg-require-and-preserve-domtree=1 < %s | FileCheck %s
 define void @foo() nounwind ssp #0 !dbg !0 {
 ; CHECK: store i32 42, i32* null
 ; CHECK-NOT: call void @llvm.trap()

diff --git a/llvm/test/Transforms/SimplifyCFG/trapping-load-unreachable.ll b/llvm/test/Transforms/SimplifyCFG/trapping-load-unreachable.ll
@@ -1,4 +1,4 @@
-; RUN: opt < %s -simplifycfg -S | FileCheck %s
+; RUN: opt < %s -simplifycfg -simplifycfg-require-and-preserve-domtree=1 -S | FileCheck %s
 ; PR2967
 
 target datalayout =

diff --git a/llvm/test/Transforms/SimplifyCFG/two-entry-phi-fold-crash.ll b/llvm/test/Transforms/SimplifyCFG/two-entry-phi-fold-crash.ll
@@ -1,5 +1,5 @@
 ; NOTE: Assertions have been autogenerated by utils/update_test_checks.py
-; RUN: opt < %s -S -simplifycfg -debug-pass=Details -enable-new-pm=0 2>&1 | FileCheck %s
+; RUN: opt < %s -S -simplifycfg -simplifycfg-require-and-preserve-domtree=1 -debug-pass=Details -enable-new-pm=0 2>&1 | FileCheck %s
 
 ;; Check the report from the pass manager, telling us whether simplifycfg
 ;; reported the "changed" status correctly:

diff --git a/llvm/test/Transforms/SimplifyCFG/two-entry-phi-return.ll b/llvm/test/Transforms/SimplifyCFG/two-entry-phi-return.ll
@@ -1,5 +1,5 @@
 ; NOTE: Assertions have been autogenerated by utils/update_test_checks.py
-; RUN: opt < %s -simplifycfg -S | FileCheck %s
+; RUN: opt < %s -simplifycfg -simplifycfg-require-and-preserve-domtree=1 -S | FileCheck %s
 
 define i1 @qux(i8* %m, i8* %n, i8* %o, i8* %p) nounwind  {
 ; CHECK-LABEL: @qux(

diff --git a/llvm/test/Transforms/SimplifyCFG/unprofitable-pr.ll b/llvm/test/Transforms/SimplifyCFG/unprofitable-pr.ll
@@ -1,5 +1,5 @@
 ; NOTE: Assertions have been autogenerated by utils/update_test_checks.py
-; RUN: opt -simplifycfg -simplifycfg-max-small-block-size=10 -S < %s | FileCheck %s
+; RUN: opt -simplifycfg -simplifycfg-require-and-preserve-domtree=1 -simplifycfg-max-small-block-size=10 -S < %s | FileCheck %s
 ; RUN: opt -passes=simplify-cfg -simplifycfg-max-small-block-size=10 -S < %s | FileCheck %s
 
 target datalayout = "e-p:64:64-p5:32:32-A5"

diff --git a/llvm/test/Transforms/SimplifyCFG/unreachable-cleanuppad.ll b/llvm/test/Transforms/SimplifyCFG/unreachable-cleanuppad.ll
@@ -1,4 +1,4 @@
-; RUN: opt -simplifycfg -S < %s | FileCheck %s
+; RUN: opt -simplifycfg -simplifycfg-require-and-preserve-domtree=1 -S < %s | FileCheck %s
 target datalayout = "e-m:x-p:32:32-i64:64-f80:32-n8:16:32-a:0:32-S32"
 target triple = "i686-pc-win32"
 

diff --git a/llvm/test/Transforms/SimplifyCFG/unreachable-selfloop.ll b/llvm/test/Transforms/SimplifyCFG/unreachable-selfloop.ll
@@ -0,0 +1,16 @@
+; NOTE: Assertions have been autogenerated by utils/update_test_checks.py
+; RUN: opt -simplifycfg -simplifycfg-require-and-preserve-domtree=1 -S < %s | FileCheck %s
+
+define void @fn() {
+; CHECK-LABEL: @fn(
+; CHECK-NEXT:  entry:
+; CHECK-NEXT:    ret void
+;
+entry:
+  ret void
+
+unreachable_bb0:
+  br label %unreachable_bb1
+unreachable_bb1:
+  br label %unreachable_bb0
+}
diff --git a/llvm/test/Transforms/SimplifyCFG/volatile-phioper.ll b/llvm/test/Transforms/SimplifyCFG/volatile-phioper.ll
@@ -1,4 +1,4 @@
-; RUN: opt < %s -simplifycfg -S | FileCheck %s
+; RUN: opt < %s -simplifycfg -simplifycfg-require-and-preserve-domtree=1 -S | FileCheck %s
 ;
 ; rdar:13349374
 ;

diff --git a/llvm/unittests/Transforms/Utils/LocalTest.cpp b/llvm/unittests/Transforms/Utils/LocalTest.cpp
@@ -999,7 +999,7 @@ TEST(Local, SimplifyCFGWithNullAC) {
   ASSERT_TRUE(TestBB);
 
   // %test.bb is expected to be simplified by FoldCondBranchOnPHI.
-  EXPECT_TRUE(simplifyCFG(TestBB, TTI, Options));
+  EXPECT_TRUE(simplifyCFG(TestBB, TTI, /*DTU=*/nullptr, Options));
 }
 
 TEST(Local, CanReplaceOperandWithVariable) {