Index: lib/CodeGen/LivePhysRegs.cpp
===================================================================
--- lib/CodeGen/LivePhysRegs.cpp
+++ lib/CodeGen/LivePhysRegs.cpp
@@ -70,6 +70,8 @@
 /// Simulates liveness when stepping backwards over an instruction(bundle):
 /// Remove Defs, add uses. This is the recommended way of calculating liveness.
 void LivePhysRegs::stepBackward(const MachineInstr &MI) {
+  if (MI.isDebugValue())
+    return;
   // Remove defined registers and regmask kills from the set.
   removeDefs(MI);
 
@@ -83,6 +85,8 @@
 /// function.
 void LivePhysRegs::stepForward(const MachineInstr &MI,
         SmallVectorImpl<std::pair<unsigned, const MachineOperand*>> &Clobbers) {
+  if (MI.isDebugValue())
+    return;
   // Remove killed registers from the set.
   for (ConstMIBundleOperands O(MI); O.isValid(); ++O) {
     if (O->isReg()) {
Index: test/CodeGen/X86/dbg-changes-codegen-branch-folding2.mir
===================================================================
--- test/CodeGen/X86/dbg-changes-codegen-branch-folding2.mir
+++ test/CodeGen/X86/dbg-changes-codegen-branch-folding2.mir
@@ -0,0 +1,213 @@
+# RUN: llc -run-pass=block-placement %s -o - | FileCheck %s
+
+--- |
+  target datalayout = "e-m:e-i64:64-f80:128-n8:16:32:64-S128"
+  target triple = "x86_64-unknown-linux-gnu"
+  
+  define void @_Z3fn1v() !dbg !6 {
+  entry:
+    %d = alloca i8, align 1
+    br i1 1, label %for.cond.cleanup, label %for.body
+  
+  for.cond.cleanup:
+    ret void
+  
+  for.body:
+    br i1 1, label %for.cond.cleanup, label %for.body.1
+  
+  for.body.1:
+    br i1 1, label %for.cond.cleanup, label %for.body.2
+  
+  for.body.2:
+    br i1 1, label %for.cond.cleanup, label %for.body.3
+  
+  for.body.3:
+    br i1 1, label %for.cond.cleanup, label %for.body.4
+  
+  for.body.4:
+    br i1 1, label %for.cond.cleanup, label %for.body.5
+  
+  for.body.5:
+    br i1 1, label %for.cond.cleanup, label %for.body.6
+  
+  for.body.6:
+    br i1 1, label %for.cond.cleanup, label %for.body.7
+  
+  for.body.7:
+    br i1 1, label %for.cond.cleanup, label %for.body.8
+  
+  for.body.8:
+    br i1 1, label %for.cond.cleanup, label %for.body.9
+  
+  for.body.9:
+    br i1 1, label %for.cond.cleanup, label %for.body.10
+  
+  for.body.10:
+    br i1 1, label %for.cond.cleanup, label %for.body.11
+  
+  for.body.11:
+    %d.0.d.0..12 = load volatile i8, i8* %d, align 1
+    call void @llvm.dbg.value(metadata i8 %d.0.d.0..12, metadata !16, metadata !DIExpression()), !dbg !19
+    br label %for.cond.cleanup
+  }
+  
+  declare void @llvm.dbg.value(metadata, metadata, metadata)
+  
+  !llvm.dbg.cu = !{!0}
+  !llvm.module.flags = !{!3, !4, !5}
+  
+  !0 = distinct !DICompileUnit(language: DW_LANG_C_plus_plus, file: !1, producer: "clang version 7.0.0 (trunk 326606)", isOptimized: true, runtimeVersion: 0, emissionKind: FullDebug, enums: !2, globals: !2)
+  !1 = !DIFile(filename: "repro.cpp", directory: "/home/mdavis/bugs/bz-189869")
+  !2 = !{}
+  !3 = !{i32 2, !"Dwarf Version", i32 4}
+  !4 = !{i32 2, !"Debug Info Version", i32 3}
+  !5 = !{i32 1, !"wchar_size", i32 4}
+  !6 = distinct !DISubprogram(name: "fn1", linkageName: "_Z3fn1v", scope: !7, file: !7, line: 4, type: !8, isLocal: false, isDefinition: true, scopeLine: 4, flags: DIFlagPrototyped, isOptimized: true, unit: !0, variables: !15)
+  !7 = !DIFile(filename: "./repro.cpp", directory: "/home/mdavis/bugs/bz-189869")
+  !8 = !DISubroutineType(types: !9)
+  !9 = !{}
+  !15 = !{!16}
+  !16 = !DILocalVariable(name: "d", scope: !6, file: !7, line: 6, type: !17)
+  !17 = !DIDerivedType(tag: DW_TAG_volatile_type, baseType: !18)
+  !18 = !DIBasicType(name: "char", size: 8, encoding: DW_ATE_signed_char)
+  !19 = !DILocation(line: 6, column: 17, scope: !6)
+
+...
+---
+# CHECK: name: _Z3fn1v
+# CHECK: bb.10.for.body.9
+# CHECK: renamable $al
+# CHECK-NEXT: TEST8rr killed renamable $al
+# CHECK-NEXT: JNE_1
+# CHECK-NOT: $al = IMPLICIT_DEF
+# CHECK: bb.12.for.body.10
+
+name:            _Z3fn1v
+alignment:       4
+tracksRegLiveness: true
+constants:       
+body:             |
+  bb.0.entry:
+    successors: %bb.1, %bb.4
+    liveins: $rdi, $rbp, $r15, $r14, $r13, $r12, $rbx
+  
+    renamable $al = MOV8ri 1
+    TEST8rr renamable $al, renamable $al, implicit-def $eflags
+    JNE_1 %bb.4, implicit killed $eflags
+  
+  bb.1.for.cond.cleanup:
+    successors: %bb.3, %bb.2
+    liveins: $ecx, $rdi
+  
+    renamable $eax = MOV32rm $rsp, 1, $noreg, -16, $noreg 
+    CMP32rm killed renamable $eax, $rip, 1, $noreg, $noreg, $noreg, implicit-def $eflags 
+    JBE_1 %bb.3, implicit $eflags
+  
+  bb.2:
+    successors: %bb.3
+    liveins: $ebp, $ebx, $edx, $esi, $rdi, $r8d, $r9d, $r10d, $r11d, $r12d, $r13d, $r14d, $r15d
+  
+  bb.3.for.cond.cleanup:
+    liveins: $rdi, $xmm3, $xmm4, $xmm5, $xmm6, $xmm7, $xmm9, $xmm13, $xmm14
+    RETQ
+  
+  bb.4.for.body:
+    successors: %bb.1, %bb.5
+    liveins: $al, $rdi
+  
+    renamable $ecx = XOR32rr undef $ecx, undef $ecx, implicit-def dead $eflags
+    TEST8rr killed renamable $al, renamable $al, implicit-def $eflags
+    JNE_1 %bb.1, implicit $eflags
+  
+  bb.5.for.body.1:
+    successors: %bb.1, %bb.6
+    liveins: $ecx, $rdi
+  
+    renamable $al = MOV8ri 1
+    TEST8rr killed renamable $al, renamable $al, implicit-def $eflags
+    JNE_1 %bb.1, implicit $eflags
+  
+  bb.6.for.body.2:
+    successors: %bb.1, %bb.7
+    liveins: $ecx, $eflags, $rdi
+  
+    JNE_1 %bb.1, implicit $eflags
+  
+  bb.7.for.body.3:
+    successors: %bb.1, %bb.8
+    liveins: $ecx, $rdi
+  
+    renamable $al = MOV8ri 1
+    TEST8rr killed renamable $al, renamable $al, implicit-def $eflags
+    JNE_1 %bb.1, implicit $eflags
+  
+  bb.8.for.body.4:
+    successors: %bb.1, %bb.9
+    liveins: $ecx, $eflags, $rdi
+  
+    JNE_1 %bb.1, implicit $eflags
+  
+  bb.9.for.body.5:
+    successors: %bb.1, %bb.10
+    liveins: $ecx, $rdi
+  
+    renamable $al = MOV8ri 1
+    TEST8rr killed renamable $al, renamable $al, implicit-def $eflags
+    JNE_1 %bb.1, implicit $eflags
+  
+  bb.10.for.body.6:
+    successors: %bb.1, %bb.11
+    liveins: $ecx, $eflags, $rdi
+  
+    JNE_1 %bb.1, implicit $eflags
+  
+  bb.11.for.body.7:
+    successors: %bb.1, %bb.12
+    liveins: $ecx, $rdi
+  
+    renamable $al = MOV8ri 1
+    TEST8rr killed renamable $al, renamable $al, implicit-def $eflags
+    JNE_1 %bb.1, implicit $eflags
+  
+  bb.12.for.body.8:
+    successors: %bb.1, %bb.13
+    liveins: $ecx, $eflags, $rdi
+  
+    JNE_1 %bb.1, implicit $eflags
+  
+  bb.13.for.body.9:
+    successors: %bb.14, %bb.15
+    liveins: $rdi
+  
+    renamable $al = MOV8ri 1
+    TEST8rr killed renamable $al, renamable $al, implicit-def $eflags
+    JE_1 %bb.15, implicit $eflags
+  
+  bb.14:
+    successors: %bb.1
+    liveins: $rdi
+  
+    renamable $ecx = XOR32rr undef $ecx, undef $ecx, implicit-def dead $eflags
+    JMP_1 %bb.1
+  
+  bb.15.for.body.10:
+    successors: %bb.16, %bb.17
+    liveins: $eflags, $rdi
+  
+    JE_1 %bb.17, implicit killed $eflags
+  
+  bb.16:
+    successors: %bb.1
+    liveins: $rdi
+  
+    JMP_1 %bb.1
+  
+  bb.17.for.body.11:
+    successors: %bb.1
+    liveins: $rdi
+  
+    dead renamable $al = MOV8rm $rsp, 1, $noreg, -121, $noreg 
+    DBG_VALUE debug-use $al, debug-use $noreg, !16, !DIExpression(), debug-location !19
+    renamable $ecx = XOR32rr undef $ecx, undef $ecx, implicit-def dead $eflags
+    JMP_1 %bb.1
+...