Index: llvm/trunk/lib/CodeGen/RegisterCoalescer.cpp
===================================================================
--- llvm/trunk/lib/CodeGen/RegisterCoalescer.cpp
+++ llvm/trunk/lib/CodeGen/RegisterCoalescer.cpp
@@ -1337,6 +1337,9 @@
       MachineInstr *UseMI = UseMO.getParent();
       if (UseMI->isDebugValue()) {
         UseMO.setReg(DstReg);
+        // Move the debug value directly after the def of the rematerialized
+        // value in DstReg.
+        MBB->splice(std::next(NewMI.getIterator()), UseMI->getParent(), UseMI);
         DEBUG(dbgs() << "\t\tupdated: " << *UseMI);
       }
     }
Index: llvm/trunk/test/DebugInfo/MIR/X86/regcoalescer.mir
===================================================================
--- llvm/trunk/test/DebugInfo/MIR/X86/regcoalescer.mir
+++ llvm/trunk/test/DebugInfo/MIR/X86/regcoalescer.mir
@@ -0,0 +1,50 @@
+# RUN: llc -O1 -filetype=asm -mtriple x86_64-unknown-linux-gnu -mcpu=x86-64 -o - %s  -start-before=simple-register-coalescing -stop-after=simple-register-coalescing | FileCheck %s
+
+--- |
+  target datalayout = "e-m:e-i64:64-f80:128-n8:16:32:64-S128"
+  target triple = "x86_64-unknown-linux-gnu"
+
+  define i32 @main() local_unnamed_addr !dbg !14 {
+  entry:
+    %shl = shl i32 undef, undef, !dbg !19
+    tail call void @llvm.dbg.value(metadata i32 %shl, metadata !18, metadata !DIExpression()), !dbg !20
+    ret i32 %shl, !dbg !21
+  }
+
+  declare void @llvm.dbg.value(metadata, metadata, metadata)
+
+  !llvm.dbg.cu = !{!0}
+  !llvm.module.flags = !{!12, !13}
+
+  !0 = distinct !DICompileUnit(language: DW_LANG_C99, file: !1, producer: "clang version 6.0.0", isOptimized: true, runtimeVersion: 0, emissionKind: FullDebug, enums: !2, globals: !2)
+  !1 = !DIFile(filename: "bar.c", directory: "")
+  !2 = !{}
+  !7 = !DIBasicType(name: "int", size: 32, encoding: DW_ATE_signed)
+  !12 = !{i32 2, !"Debug Info Version", i32 3}
+  !13 = !{i32 1, !"wchar_size", i32 4}
+  !14 = distinct !DISubprogram(name: "main", scope: !1, file: !1, line: 12, type: !15, isLocal: false, isDefinition: true, scopeLine: 12, isOptimized: true, unit: !0, variables: !17)
+  !15 = !DISubroutineType(types: !16)
+  !16 = !{!7}
+  !17 = !{!18}
+  !18 = !DILocalVariable(name: "bazinga", scope: !14, file: !1, line: 13, type: !7)
+  !19 = !DILocation(line: 14, column: 11, scope: !14)
+  !20 = !DILocation(line: 13, column: 7, scope: !14)
+  !21 = !DILocation(line: 16, column: 3, scope: !14)
+
+...
+---
+name:            main
+alignment:       4
+registers:
+  - { id: 0, class: gr32, preferred-register: '' }
+body:             |
+  bb.0.entry:
+    %0 = MOV32r0 implicit-def dead %eflags, debug-location !19
+    DBG_VALUE debug-use %0, debug-use _, !18, !DIExpression(), debug-location !20
+    %eax = COPY killed %0, debug-location !21
+    RET 0, killed %eax, debug-location !21
+
+...
+
+# CHECK: %eax = MOV32r0
+# CHECK-NEXT: DBG_VALUE debug-use %eax