diff --git a/llvm/lib/Transforms/Scalar/SimpleLoopUnswitch.cpp b/llvm/lib/Transforms/Scalar/SimpleLoopUnswitch.cpp
--- a/llvm/lib/Transforms/Scalar/SimpleLoopUnswitch.cpp
+++ b/llvm/lib/Transforms/Scalar/SimpleLoopUnswitch.cpp
@@ -2070,6 +2070,13 @@
         DominatingSucc, *VMaps.back(), DTUpdates, AC, DT, LI, MSSAU);
   }
 
+  // Drop metadata if we may break its semantics by moving this branch into the
+  // split block.
+  // TODO: We can keep make.implicit metadata if we prove that TI always
+  // executes and we cannot leave unswitched loop before getting to null check
+  // block. See @test_may_keep_make_implicit_non_trivial.
+  TI.setMetadata(LLVMContext::MD_make_implicit, nullptr);
+
   // The stitching of the branched code back together depends on whether we're
   // doing full unswitching or not with the exception that we always want to
   // nuke the initial terminator placed in the split block.
diff --git a/llvm/test/Transforms/SimpleLoopUnswitch/implicit-null-checks.ll b/llvm/test/Transforms/SimpleLoopUnswitch/implicit-null-checks.ll
new file mode 100644
--- /dev/null
+++ b/llvm/test/Transforms/SimpleLoopUnswitch/implicit-null-checks.ll
@@ -0,0 +1,211 @@
+; NOTE: Assertions have been autogenerated by utils/update_test_checks.py
+; RUN: opt -enable-nontrivial-unswitch=true -simple-loop-unswitch -S < %s | FileCheck %s
+; RUN: opt -enable-nontrivial-unswitch=true -passes='loop(unswitch),verify<loops>' -S < %s | FileCheck %s
+
+declare void @throw_npe()
+
+; It is illegal to preserve make_implicit notion of the condition being
+; unswitched because we may exit loop before we reach the condition, so
+; there is no guarantee that following implicit branch always means getting
+; to throw_npe block.
+define i32 @test_should_drop_make_implicit(i32* %p1, i32* %p2) {
+; CHECK-LABEL: @test_should_drop_make_implicit(
+; CHECK-NEXT:  entry:
+; CHECK-NEXT:    [[NULL_CHECK:%.*]] = icmp eq i32* [[P2:%.*]], null
+; CHECK-NOT:     !make.implicit
+; CHECK-NEXT:    br i1 [[NULL_CHECK]], label [[ENTRY_SPLIT_US:%.*]], label [[ENTRY_SPLIT:%.*]]
+; CHECK:       entry.split.us:
+; CHECK-NEXT:    br label [[LOOP_US:%.*]]
+; CHECK:       loop.us:
+; CHECK-NEXT:    [[IV_US:%.*]] = phi i32 [ 0, [[ENTRY_SPLIT_US]] ]
+; CHECK-NEXT:    [[X_US:%.*]] = load i32, i32* [[P1:%.*]], align 4
+; CHECK-NEXT:    [[SIDE_EXIT_COND_US:%.*]] = icmp eq i32 [[X_US]], 0
+; CHECK-NEXT:    br i1 [[SIDE_EXIT_COND_US]], label [[SIDE_EXIT_SPLIT_US:%.*]], label [[NULL_CHECK_BLOCK_US:%.*]]
+; CHECK:       null_check_block.us:
+; CHECK-NEXT:    br label [[THROW_NPE_SPLIT_US:%.*]]
+; CHECK:       side_exit.split.us:
+; CHECK-NEXT:    br label [[SIDE_EXIT:%.*]]
+; CHECK:       throw_npe.split.us:
+; CHECK-NEXT:    br label [[THROW_NPE:%.*]]
+; CHECK:       entry.split:
+; CHECK-NEXT:    br label [[LOOP:%.*]]
+; CHECK:       loop:
+; CHECK-NEXT:    [[IV:%.*]] = phi i32 [ 0, [[ENTRY_SPLIT]] ], [ [[IV_NEXT:%.*]], [[BACKEDGE:%.*]] ]
+; CHECK-NEXT:    [[X:%.*]] = load i32, i32* [[P1]], align 4
+; CHECK-NEXT:    [[SIDE_EXIT_COND:%.*]] = icmp eq i32 [[X]], 0
+; CHECK-NEXT:    br i1 [[SIDE_EXIT_COND]], label [[SIDE_EXIT_SPLIT:%.*]], label [[NULL_CHECK_BLOCK:%.*]]
+; CHECK:       null_check_block:
+; CHECK-NEXT:    br label [[BACKEDGE]]
+; CHECK:       backedge:
+; CHECK-NEXT:    [[IV_NEXT]] = add i32 [[IV]], 1
+; CHECK-NEXT:    [[LOOP_COND:%.*]] = icmp slt i32 [[IV_NEXT]], 10000
+; CHECK-NEXT:    br i1 [[LOOP_COND]], label [[LOOP]], label [[EXIT:%.*]]
+; CHECK:       side_exit.split:
+; CHECK-NEXT:    br label [[SIDE_EXIT]]
+; CHECK:       side_exit:
+; CHECK-NEXT:    ret i32 0
+; CHECK:       throw_npe:
+; CHECK-NEXT:    call void @throw_npe()
+; CHECK-NEXT:    unreachable
+; CHECK:       exit:
+; CHECK-NEXT:    [[X_LCSSA2:%.*]] = phi i32 [ [[X]], [[BACKEDGE]] ]
+; CHECK-NEXT:    ret i32 [[X_LCSSA2]]
+;
+entry:
+  %null_check = icmp eq i32* %p2, null
+  br label %loop
+loop:
+  %iv = phi i32 [0, %entry], [%iv.next, %backedge]
+  %x = load i32, i32* %p1
+  %side_exit_cond = icmp eq i32 %x, 0
+  br i1 %side_exit_cond, label %side_exit, label %null_check_block
+
+null_check_block:
+  br i1 %null_check, label %throw_npe, label %backedge, !make.implicit !0
+
+backedge:
+  %iv.next = add i32 %iv,1
+  %loop_cond = icmp slt i32 %iv.next, 10000
+  br i1 %loop_cond, label %loop, label %exit
+
+side_exit:
+  ret i32 0
+
+throw_npe:
+  call void @throw_npe()
+  unreachable
+
+exit:
+  ret i32 %x
+}
+
+; Here make.implicit notion may be preserved because we always get to throw_npe
+; after following true branch. This is a trivial unswitch.
+define i32 @test_may_keep_make_implicit_trivial(i32* %p1, i32* %p2) {
+; CHECK-LABEL: @test_may_keep_make_implicit_trivial(
+; CHECK-NEXT:  entry:
+; CHECK-NEXT:    [[NULL_CHECK:%.*]] = icmp eq i32* [[P2:%.*]], null
+; CHECK-NEXT:    br i1 [[NULL_CHECK]], label [[THROW_NPE:%.*]], label [[ENTRY_SPLIT:%.*]], !make.implicit !0
+; CHECK:       entry.split:
+; CHECK-NEXT:    br label [[LOOP:%.*]]
+; CHECK:       loop:
+; CHECK-NEXT:    [[IV:%.*]] = phi i32 [ 0, [[ENTRY_SPLIT]] ], [ [[IV_NEXT:%.*]], [[BACKEDGE:%.*]] ]
+; CHECK-NEXT:    [[X:%.*]] = load i32, i32* [[P1:%.*]], align 4
+; CHECK-NEXT:    [[SIDE_EXIT_COND:%.*]] = icmp eq i32 [[X]], 0
+; CHECK-NEXT:    br label [[SIDE_EXIT_BLOCK:%.*]]
+; CHECK:       side_exit_block:
+; CHECK-NEXT:    br i1 [[SIDE_EXIT_COND]], label [[SIDE_EXIT:%.*]], label [[BACKEDGE]]
+; CHECK:       backedge:
+; CHECK-NEXT:    [[IV_NEXT]] = add i32 [[IV]], 1
+; CHECK-NEXT:    [[LOOP_COND:%.*]] = icmp slt i32 [[IV_NEXT]], 10000
+; CHECK-NEXT:    br i1 [[LOOP_COND]], label [[LOOP]], label [[EXIT:%.*]]
+; CHECK:       side_exit:
+; CHECK-NEXT:    ret i32 0
+; CHECK:       throw_npe:
+; CHECK-NEXT:    call void @throw_npe()
+; CHECK-NEXT:    unreachable
+; CHECK:       exit:
+; CHECK-NEXT:    [[X_LCSSA2:%.*]] = phi i32 [ [[X]], [[BACKEDGE]] ]
+; CHECK-NEXT:    ret i32 [[X_LCSSA2]]
+;
+entry:
+  %null_check = icmp eq i32* %p2, null
+  br label %loop
+loop:
+  %iv = phi i32 [0, %entry], [%iv.next, %backedge]
+  %x = load i32, i32* %p1
+  %side_exit_cond = icmp eq i32 %x, 0
+  br i1 %null_check, label %throw_npe, label %side_exit_block, !make.implicit !0
+
+side_exit_block:
+  br i1 %side_exit_cond, label %side_exit, label %backedge
+
+backedge:
+  %iv.next = add i32 %iv,1
+  %loop_cond = icmp slt i32 %iv.next, 10000
+  br i1 %loop_cond, label %loop, label %exit
+
+side_exit:
+  ret i32 0
+
+throw_npe:
+  call void @throw_npe()
+  unreachable
+
+exit:
+  ret i32 %x
+}
+
+; TODO: This is a non-trivial unswitch, but it would still be legal to keep
+; !make.implicit in entry block. Currently we do not have enough analysis to
+; prove it.
+define i32 @test_may_keep_make_implicit_non_trivial(i32* %p1, i32* %p2) {
+; CHECK-LABEL: @test_may_keep_make_implicit_non_trivial(
+; CHECK-NEXT:  entry:
+; CHECK-NEXT:    [[NULL_CHECK:%.*]] = icmp eq i32* [[P2:%.*]], null
+; CHECK-NOT:     !make.implicit
+; CHECK-NEXT:    br i1 [[NULL_CHECK]], label [[ENTRY_SPLIT_US:%.*]], label [[ENTRY_SPLIT:%.*]]
+; CHECK:       entry.split.us:
+; CHECK-NEXT:    br label [[LOOP_US:%.*]]
+; CHECK:       loop.us:
+; CHECK-NEXT:    [[IV_US:%.*]] = phi i32 [ 0, [[ENTRY_SPLIT_US]] ]
+; CHECK-NEXT:    [[X_US:%.*]] = load i32, i32* [[P1:%.*]], align 4
+; CHECK-NEXT:    [[INNER_BLOCK_COND_US:%.*]] = icmp eq i32 [[X_US]], 0
+; CHECK-NEXT:    br i1 [[INNER_BLOCK_COND_US]], label [[INNER_BLOCK_US:%.*]], label [[NULL_CHECK_BLOCK_US:%.*]]
+; CHECK:       inner_block.us:
+; CHECK-NEXT:    br label [[NULL_CHECK_BLOCK_US]]
+; CHECK:       null_check_block.us:
+; CHECK-NEXT:    br label [[THROW_NPE_SPLIT_US:%.*]]
+; CHECK:       throw_npe.split.us:
+; CHECK-NEXT:    br label [[THROW_NPE:%.*]]
+; CHECK:       entry.split:
+; CHECK-NEXT:    br label [[LOOP:%.*]]
+; CHECK:       loop:
+; CHECK-NEXT:    [[IV:%.*]] = phi i32 [ 0, [[ENTRY_SPLIT]] ], [ [[IV_NEXT:%.*]], [[BACKEDGE:%.*]] ]
+; CHECK-NEXT:    [[X:%.*]] = load i32, i32* [[P1]], align 4
+; CHECK-NEXT:    [[INNER_BLOCK_COND:%.*]] = icmp eq i32 [[X]], 0
+; CHECK-NEXT:    br i1 [[INNER_BLOCK_COND]], label [[INNER_BLOCK:%.*]], label [[NULL_CHECK_BLOCK:%.*]]
+; CHECK:       inner_block:
+; CHECK-NEXT:    br label [[NULL_CHECK_BLOCK]]
+; CHECK:       null_check_block:
+; CHECK-NEXT:    br label [[BACKEDGE]]
+; CHECK:       backedge:
+; CHECK-NEXT:    [[IV_NEXT]] = add i32 [[IV]], 1
+; CHECK-NEXT:    [[LOOP_COND:%.*]] = icmp slt i32 [[IV_NEXT]], 10000
+; CHECK-NEXT:    br i1 [[LOOP_COND]], label [[LOOP]], label [[EXIT:%.*]]
+; CHECK:       throw_npe:
+; CHECK-NEXT:    call void @throw_npe()
+; CHECK-NEXT:    unreachable
+; CHECK:       exit:
+; CHECK-NEXT:    [[X_LCSSA1:%.*]] = phi i32 [ [[X]], [[BACKEDGE]] ]
+; CHECK-NEXT:    ret i32 [[X_LCSSA1]]
+;
+entry:
+  %null_check = icmp eq i32* %p2, null
+  br label %loop
+loop:
+  %iv = phi i32 [0, %entry], [%iv.next, %backedge]
+  %x = load i32, i32* %p1
+  %inner_block_cond = icmp eq i32 %x, 0
+  br i1 %inner_block_cond, label %inner_block, label %null_check_block
+
+inner_block:
+  br label %null_check_block
+
+null_check_block:
+  br i1 %null_check, label %throw_npe, label %backedge, !make.implicit !0
+
+backedge:
+  %iv.next = add i32 %iv,1
+  %loop_cond = icmp slt i32 %iv.next, 10000
+  br i1 %loop_cond, label %loop, label %exit
+
+throw_npe:
+  call void @throw_npe()
+  unreachable
+
+exit:
+  ret i32 %x
+}
+
+!0 = !{}