Index: llvm/lib/CodeGen/LiveDebugVariables.cpp
===================================================================
--- llvm/lib/CodeGen/LiveDebugVariables.cpp
+++ llvm/lib/CodeGen/LiveDebugVariables.cpp
@@ -1636,6 +1636,32 @@
   return MBB->end();
 }
 
+// Avoid duplicates by scanning the machine basic block backward, up to the
+// first non-debug instr or up to the MBBStart.
+static bool shouldSkipThisDbgValue(MachineBasicBlock *MBB, MachineInstr &MI,
+                                   const DILocalVariable *Variable,
+                                   const MachineOperand &LocOp,
+                                   const DIExpression *Expr, DebugLoc &dl) {
+  MachineBasicBlock::reverse_iterator it =
+      std::next(MachineBasicBlock::reverse_iterator(MI));
+  while (it != MBB->rend()) {
+    if (!it->isDebugValue())
+      return false;
+
+    MachineOperand &loc = it->getDebugOperand(0);
+    if (Variable == it->getDebugVariable() && loc.isReg() && LocOp.isReg() &&
+        loc.getReg() == LocOp.getReg() && Expr == it->getDebugExpression() &&
+        dl == it->getDebugLoc()) {
+      LLVM_DEBUG(llvm::dbgs() << "\navoiding duplicated "; it->dump(););
+      return true;
+    }
+
+    it = std::next(it);
+  }
+
+  return false;
+}
+
 void UserValue::insertDebugValue(MachineBasicBlock *MBB, SlotIndex StartIdx,
                                  SlotIndex StopIdx, DbgVariableValue DbgValue,
                                  ArrayRef<bool> LocSpills,
@@ -1648,6 +1674,15 @@
   StopIdx = (MBBEndIdx < StopIdx) ? MBBEndIdx : StopIdx;
   MachineBasicBlock::iterator I =
       findInsertLocation(MBB, StartIdx, LIS, BBSkipInstsMap);
+
+  // After virtual register rewriting, we can end up having multiple same
+  // contiguous DBG_VALUEs representing the same variable, so we are avoiding
+  // duplicates here.
+  if (locations.size() == 1 && I != MBB->end() &&
+      shouldSkipThisDbgValue(MBB, *I, Variable, locations[0],
+                             DbgValue.getExpression(), dl))
+    return;
+
   // Undef values don't exist in locations so create new "noreg" register MOs
   // for them. See getLocationNo().
   SmallVector<MachineOperand, 8> MOs;
Index: llvm/test/CodeGen/AMDGPU/ptr-arg-dbg-value.ll
===================================================================
--- llvm/test/CodeGen/AMDGPU/ptr-arg-dbg-value.ll
+++ llvm/test/CodeGen/AMDGPU/ptr-arg-dbg-value.ll
@@ -43,7 +43,8 @@
 ; CHECK-NEXT:    .loc 1 10 0 ; example.cpp:10:0
 ; CHECK-NEXT:    .cfi_startproc
 ; CHECK-NEXT:  ; %bb.0:
-; CHECK-NEXT:    ;DEBUG_VALUE: ptr_arg_split_reg_mem:b <- [$vgpr31+0]
+;; NOTE: One dbg_value (DEBUG_VALUE: ptr_arg_split_reg_mem:b <- [$vgpr31+0]) will be considered as
+;; redundant after the virtregrewrite, so it will be removed.
 ; CHECK-NEXT:    ;DEBUG_VALUE: ptr_arg_split_reg_mem:b <- [$vgpr31+0]
 ; CHECK-NEXT:    s_waitcnt vmcnt(0) expcnt(0) lgkmcnt(0)
 ; CHECK-NEXT:    buffer_load_dword v32, off, s[0:3], s32
Index: llvm/test/CodeGen/PowerPC/non-debug-mi-search-frspxsrsp.ll
===================================================================
--- llvm/test/CodeGen/PowerPC/non-debug-mi-search-frspxsrsp.ll
+++ llvm/test/CodeGen/PowerPC/non-debug-mi-search-frspxsrsp.ll
@@ -5,7 +5,6 @@
 ; CHECK-LABEL: test:
 ; CHECK:       # %bb.0: # %entry
 ; CHECK-NEXT:          #DEBUG_VALUE: test:Fptr <- $x3
-; CHECK-NEXT:          #DEBUG_VALUE: test:Fptr <- $x3
 ; CHECK-NEXT:          #DEBUG_VALUE: test:Vptr <- $x4
 ; CHECK-NEXT:          addis 5, 2, .LCPI0_0@toc@ha
 ; CHECK-NEXT:  .Ltmp0:
Index: llvm/test/DebugInfo/MIR/Hexagon/live-debug-values-bundled-entry-values.mir
===================================================================
--- llvm/test/DebugInfo/MIR/Hexagon/live-debug-values-bundled-entry-values.mir
+++ llvm/test/DebugInfo/MIR/Hexagon/live-debug-values-bundled-entry-values.mir
@@ -112,7 +112,6 @@
     successors: %bb.1
     liveins: $r0
 
-    DBG_VALUE $r0, $noreg, !22, !DIExpression(), debug-location !23
     DBG_VALUE $r0, $noreg, !22, !DIExpression(), debug-location !23
     BUNDLE implicit-def dead $p0, implicit-def $pc, implicit killed $r0, implicit killed $r31, debug-location !24 {
       renamable $p0 = C2_cmpeqi killed renamable $r0, 0, debug-location !24
Index: llvm/test/DebugInfo/MIR/X86/multiple-param-dbg-value-entry.mir
===================================================================
--- llvm/test/DebugInfo/MIR/X86/multiple-param-dbg-value-entry.mir
+++ llvm/test/DebugInfo/MIR/X86/multiple-param-dbg-value-entry.mir
@@ -70,7 +70,6 @@
   bb.0.entry:
     liveins: $edi
 
-    DBG_VALUE $edi, $noreg, !15, !DIExpression(), debug-location !18
     DBG_VALUE $edi, $noreg, !15, !DIExpression(), debug-location !18
     DBG_VALUE $esi, $noreg, !16, !DIExpression(), debug-location !18
     DBG_VALUE $edx, $noreg, !17, !DIExpression(), debug-location !18
Index: llvm/test/DebugInfo/X86/livedebugvars-avoid-duplicates.ll
===================================================================
--- /dev/null
+++ llvm/test/DebugInfo/X86/livedebugvars-avoid-duplicates.ll
@@ -0,0 +1,59 @@
+;; Check that after virtregrewrite MIR does not contain
+;; redundant DBG_VALUEs.
+
+; RUN: llc -O2 %s -stop-before=livedebugvalues -o - | FileCheck %s
+
+; CHECK: DBG_VALUE $edi, $noreg, !13, !DIExpression(), debug-location !14
+; CHECK-NEXT: frame-setup
+; CHECK: DBG_VALUE $edi, $noreg, !13, !DIExpression(), debug-location !14
+
+; ModuleID = 'test.c'
+source_filename = "test.c"
+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"
+
+@side_effect = external dso_local local_unnamed_addr global i32, align 4
+@value = external dso_local local_unnamed_addr global i32, align 4
+
+; Function Attrs: nounwind uwtable
+define dso_local i32 @foo(i32 %param) local_unnamed_addr !dbg !8 {
+entry:
+  call void @llvm.dbg.value(metadata i32 %param, metadata !13, metadata !DIExpression()), !dbg !14
+  store i32 %param, i32* @side_effect, align 4, !dbg !15
+  %0 = load i32, i32* @value, align 4, !dbg !20
+  call void @llvm.dbg.value(metadata i32 %0, metadata !13, metadata !DIExpression()), !dbg !14
+  tail call void @bar(i32 %0), !dbg !21
+  ret i32 0, !dbg !22
+}
+
+declare !dbg !23 dso_local void @bar(i32) local_unnamed_addr
+
+; Function Attrs: nofree nosync nounwind readnone speculatable willreturn mustprogress
+declare void @llvm.dbg.value(metadata, metadata, metadata)
+
+!llvm.dbg.cu = !{!0}
+!llvm.module.flags = !{!3, !4, !5, !6}
+!llvm.ident = !{!7}
+
+!0 = distinct !DICompileUnit(language: DW_LANG_C99, file: !1, producer: "clang version 13.0.0", isOptimized: true, runtimeVersion: 0, emissionKind: FullDebug, enums: !2, splitDebugInlining: false, nameTableKind: None)
+!1 = !DIFile(filename: "test.c", directory: "/dir")
+!2 = !{}
+!3 = !{i32 7, !"Dwarf Version", i32 4}
+!4 = !{i32 2, !"Debug Info Version", i32 3}
+!5 = !{i32 1, !"wchar_size", i32 4}
+!6 = !{i32 7, !"uwtable", i32 1}
+!7 = !{!"clang version 13.0.0"}
+!8 = distinct !DISubprogram(name: "foo", scope: !1, file: !1, line: 4, type: !9, scopeLine: 4, flags: DIFlagPrototyped | DIFlagAllCallsDescribed, spFlags: DISPFlagDefinition | DISPFlagOptimized, unit: !0, retainedNodes: !12)
+!9 = !DISubroutineType(types: !10)
+!10 = !{!11, !11}
+!11 = !DIBasicType(name: "int", size: 32, encoding: DW_ATE_signed)
+!12 = !{!13}
+!13 = !DILocalVariable(name: "param", arg: 1, scope: !8, file: !1, line: 4, type: !11)
+!14 = !DILocation(line: 0, scope: !8)
+!15 = !DILocation(line: 5, column: 17, scope: !8)
+!20 = !DILocation(line: 6, column: 13, scope: !8)
+!21 = !DILocation(line: 7, column: 5, scope: !8)
+!22 = !DILocation(line: 8, column: 5, scope: !8)
+!23 = !DISubprogram(name: "bar", scope: !1, file: !1, line: 1, type: !24, flags: DIFlagPrototyped, spFlags: DISPFlagOptimized, retainedNodes: !2)
+!24 = !DISubroutineType(types: !25)
+!25 = !{null, !11}