Index: llvm/lib/CodeGen/LiveDebugValues.cpp
===================================================================
--- llvm/lib/CodeGen/LiveDebugValues.cpp
+++ llvm/lib/CodeGen/LiveDebugValues.cpp
@@ -109,6 +109,8 @@
 
 namespace {
 
+using DefinedRegsSet = SmallSet<Register, 32>;
+
 class LiveDebugValues : public MachineFunctionPass {
 private:
   const TargetRegisterInfo *TRI;
@@ -479,7 +481,8 @@
   ///
   /// Currently, we generate debug entry values only for parameters that are
   /// unmodified throughout the function and located in a register.
-  bool isEntryValueCandidate(const MachineInstr &MI) const;
+  bool isEntryValueCandidate(const MachineInstr &MI,
+                             const DefinedRegsSet &Regs) const;
 
   /// If a given instruction is identified as a spill, return the spill location
   /// and set \p Reg to the spilled register.
@@ -1274,7 +1277,8 @@
   }
 }
 
-bool LiveDebugValues::isEntryValueCandidate(const MachineInstr &MI) const {
+bool LiveDebugValues::isEntryValueCandidate(
+    const MachineInstr &MI, const DefinedRegsSet &DefinedRegs) const {
   if (!MI.isDebugValue())
     return false;
 
@@ -1300,6 +1304,13 @@
   if (!isRegOtherThanSPAndFP(MI.getOperand(0), MI, TRI))
     return false;
 
+  // If a parameter's value has been propagated from the caller, then the
+  // parameter's DBG_VALUE may be described using a register defined by some
+  // instruction in the entry block, in which case we shouldn't create an
+  // entry value.
+  if (DefinedRegs.count(MI.getOperand(0).getReg()))
+    return false;
+
   // TODO: Add support for parameters that are described as fragments.
   if (MI.getDebugExpression()->isFragment())
     return false;
@@ -1307,6 +1318,15 @@
   return true;
 }
 
+/// Collect all register defines (including aliases) for the given instruction.
+static void collectRegDefs(const MachineInstr &MI, DefinedRegsSet &Regs,
+                           const TargetRegisterInfo *TRI) {
+  for (const MachineOperand &MO : MI.operands())
+    if (MO.isReg() && MO.isDef() && MO.getReg())
+      for (MCRegAliasIterator AI(MO.getReg(), TRI, true); AI.isValid(); ++AI)
+        Regs.insert(*AI);
+}
+
 /// Calculate the liveness information for the given machine function and
 /// extend ranges across basic blocks.
 bool LiveDebugValues::ExtendRanges(MachineFunction &MF) {
@@ -1347,13 +1367,20 @@
   // representing candidates for production of debug entry values.
   DebugParamMap DebugEntryVals;
 
+  // Set of register defines that are seen when traversing the entry block
+  // looking for debug entry value candidates.
+  DefinedRegsSet DefinedRegs;
+
   // Only in the case of entry MBB collect DBG_VALUEs representing
   // function parameters in order to generate debug entry values for them.
+
   MachineBasicBlock &First_MBB = *(MF.begin());
-  for (auto &MI : First_MBB)
-    if (isEntryValueCandidate(MI) &&
+  for (auto &MI : First_MBB) {
+    collectRegDefs(MI, DefinedRegs, TRI);
+    if (isEntryValueCandidate(MI, DefinedRegs) &&
         !DebugEntryVals.count(MI.getDebugVariable()))
       DebugEntryVals[MI.getDebugVariable()] = &MI;
+  }
 
   // Initialize per-block structures and scan for fragment overlaps.
   for (auto &MBB : MF) {
Index: llvm/test/DebugInfo/MIR/ARM/dbgcall-site-propagated-value.mir
===================================================================
--- /dev/null
+++ llvm/test/DebugInfo/MIR/ARM/dbgcall-site-propagated-value.mir
@@ -0,0 +1,185 @@
+# RUN: llc -debug-entry-values -run-pass=livedebugvalues -o - %s | FileCheck %s
+
+# Based on the following C reproducer:
+#
+# extern void ext(int *);
+# extern int interesting(int *);
+# extern int *value(void);
+#
+# static void callee(int *p1, int *p2) {
+#   if (interesting(p2))
+#     for (;;)
+#       ext(p1);
+#   ext(p2);
+# }
+#
+# void caller() {
+#   int *local = value();
+#   callee(local, (int *)0xabcd);
+# }
+#
+# Generated using:
+#
+# clang -Os -fno-inline -Xclang -femit-debug-entry-values -g --target=armeb.
+
+--- |
+  target datalayout = "E-m:e-p:32:32-Fi8-i64:64-v128:64:128-a:0:32-n32-S64"
+  target triple = "armebv4t-unknown-unknown"
+
+  ; Function Attrs: noinline nounwind optsize
+  define arm_aapcs_vfpcc void @caller() #0 !dbg !20 {
+  entry:
+    unreachable
+  }
+
+  ; Function Attrs: noinline nounwind optsize
+  define internal arm_aapcs_vfpcc void @callee(i32* %p1) unnamed_addr #0 !dbg !29 {
+  entry:
+    unreachable
+  }
+
+  declare !dbg !4 arm_aapcs_vfpcc i32* @value()
+  declare !dbg !9 arm_aapcs_vfpcc i32 @interesting(i32*)
+  declare !dbg !12 arm_aapcs_vfpcc void @ext(i32*)
+
+  ; Function Attrs: nounwind readnone speculatable willreturn
+  declare void @llvm.dbg.value(metadata, metadata, metadata) #1
+
+  attributes #0 = { noinline nounwind optsize "frame-pointer"="all" }
+  attributes #1 = { nounwind readnone speculatable willreturn }
+
+  !llvm.dbg.cu = !{!0}
+  !llvm.module.flags = !{!15, !16, !17, !18}
+  !llvm.ident = !{!19}
+
+  !0 = distinct !DICompileUnit(language: DW_LANG_C99, file: !1, producer: "clang version 10.0.0", isOptimized: true, runtimeVersion: 0, emissionKind: FullDebug, enums: !2, retainedTypes: !3, nameTableKind: None)
+  !1 = !DIFile(filename: "armeb.c", directory: "/")
+  !2 = !{}
+  !3 = !{!4, !7, !9, !12}
+  !4 = !DISubprogram(name: "value", scope: !1, file: !1, line: 3, type: !5, flags: DIFlagPrototyped, spFlags: DISPFlagOptimized, retainedNodes: !2)
+  !5 = !DISubroutineType(types: !6)
+  !6 = !{!7}
+  !7 = !DIDerivedType(tag: DW_TAG_pointer_type, baseType: !8, size: 32)
+  !8 = !DIBasicType(name: "int", size: 32, encoding: DW_ATE_signed)
+  !9 = !DISubprogram(name: "interesting", scope: !1, file: !1, line: 2, type: !10, flags: DIFlagPrototyped, spFlags: DISPFlagOptimized, retainedNodes: !2)
+  !10 = !DISubroutineType(types: !11)
+  !11 = !{!8, !7}
+  !12 = !DISubprogram(name: "ext", scope: !1, file: !1, line: 1, type: !13, flags: DIFlagPrototyped, spFlags: DISPFlagOptimized, retainedNodes: !2)
+  !13 = !DISubroutineType(types: !14)
+  !14 = !{null, !7}
+  !15 = !{i32 2, !"Dwarf Version", i32 4}
+  !16 = !{i32 2, !"Debug Info Version", i32 3}
+  !17 = !{i32 1, !"wchar_size", i32 4}
+  !18 = !{i32 1, !"min_enum_size", i32 4}
+  !19 = !{!"clang version 10.0.0"}
+  !20 = distinct !DISubprogram(name: "caller", scope: !1, file: !1, line: 12, type: !21, scopeLine: 12, flags: DIFlagAllCallsDescribed, spFlags: DISPFlagDefinition | DISPFlagOptimized, unit: !0, retainedNodes: !23)
+  !21 = !DISubroutineType(types: !22)
+  !22 = !{null}
+  !23 = !{!24}
+  !24 = !DILocalVariable(name: "local", scope: !20, file: !1, line: 13, type: !7)
+  !25 = !DILocation(line: 13, scope: !20)
+  !26 = !DILocation(line: 0, scope: !20)
+  !27 = !DILocation(line: 14, scope: !20)
+  !28 = !DILocation(line: 15, scope: !20)
+  !29 = distinct !DISubprogram(name: "callee", scope: !1, file: !1, line: 5, type: !30, scopeLine: 5, flags: DIFlagPrototyped | DIFlagAllCallsDescribed, spFlags: DISPFlagLocalToUnit | DISPFlagDefinition | DISPFlagOptimized, unit: !0, retainedNodes: !32)
+  !30 = !DISubroutineType(types: !31)
+  !31 = !{null, !7, !7}
+  !32 = !{!33, !34}
+  !33 = !DILocalVariable(name: "p1", arg: 1, scope: !29, file: !1, line: 5, type: !7, flags: DIFlagArgumentNotModified)
+  !34 = !DILocalVariable(name: "p2", arg: 2, scope: !29, file: !1, line: 5, type: !7, flags: DIFlagArgumentNotModified)
+  !35 = !DILocation(line: 0, scope: !29)
+  !36 = !DILocation(line: 6, scope: !37)
+  !37 = distinct !DILexicalBlock(scope: !29, file: !1, line: 6)
+  !38 = !DILocation(line: 6, scope: !29)
+  !39 = !DILocation(line: 7, scope: !40)
+  !40 = distinct !DILexicalBlock(scope: !37, file: !1, line: 7)
+  !41 = !DILocation(line: 8, scope: !42)
+  !42 = distinct !DILexicalBlock(scope: !40, file: !1, line: 7)
+  !43 = !DILocation(line: 7, scope: !42)
+  !44 = distinct !{!44, !39, !45}
+  !45 = !DILocation(line: 8, scope: !40)
+  !46 = !DILocation(line: 9, scope: !29)
+  !47 = !DILocation(line: 10, scope: !29)
+
+...
+---
+name:            caller
+alignment:       4
+tracksRegLiveness: true
+callSites:
+  - { bb: 0, offset: 6 }
+  - { bb: 0, offset: 9, fwdArgRegs:
+      - { arg: 0, reg: '$r0' } }
+body:             |
+  bb.0:
+    liveins: $lr
+
+    $sp = frame-setup STMDB_UPD $sp, 14, $noreg, $r11, killed $lr
+    frame-setup CFI_INSTRUCTION def_cfa_offset 8
+    frame-setup CFI_INSTRUCTION offset $lr, -4
+    frame-setup CFI_INSTRUCTION offset $r11, -8
+    $r11 = frame-setup MOVr $sp, 14, $noreg, $noreg
+    frame-setup CFI_INSTRUCTION def_cfa_register $r11
+    BL @value, csr_aapcs, implicit-def dead $lr, implicit $sp, implicit-def $sp, implicit-def $r0, debug-location !25
+    DBG_VALUE $r0, $noreg, !24, !DIExpression(), debug-location !26
+    $sp = LDMIA_UPD $sp, 14, $noreg, def $r11, def $lr, debug-location !27
+    TAILJMPd @callee, implicit $sp, implicit $sp, implicit killed $r0, debug-location !27
+
+...
+---
+name:            callee
+tracksRegLiveness: true
+body:             |
+  bb.0:
+    successors: %bb.2(0x30000000), %bb.1(0x50000000)
+    liveins: $r0, $r4, $r10, $lr
+
+    DBG_VALUE $r0, $noreg, !33, !DIExpression(), debug-location !35
+    $sp = frame-setup STMDB_UPD $sp, 14, $noreg, killed $r4, killed $r10, $r11, killed $lr
+    frame-setup CFI_INSTRUCTION def_cfa_offset 16
+    frame-setup CFI_INSTRUCTION offset $lr, -4
+    frame-setup CFI_INSTRUCTION offset $r11, -8
+    frame-setup CFI_INSTRUCTION offset $r10, -12
+    frame-setup CFI_INSTRUCTION offset $r4, -16
+    $r11 = frame-setup ADDri $sp, 8, 14, $noreg, $noreg
+    frame-setup CFI_INSTRUCTION def_cfa $r11, 8
+    $r4 = MOVr killed $r0, 14, $noreg, $noreg
+    DBG_VALUE $r4, $noreg, !33, !DIExpression(), debug-location !35
+    $r0 = MOVi 205, 14, $noreg, $noreg
+    $r0 = ORRri killed $r0, 43776, 14, $noreg, $noreg
+    ; The MOVI and ORRri produce the second parameter's (!34) value which has
+    ; been propagated from caller().
+    DBG_VALUE $r0, $noreg, !34, !DIExpression(), debug-location !35
+    BL @interesting, csr_aapcs, implicit-def dead $lr, implicit $sp, implicit killed $r0, implicit-def $sp, implicit-def $r0, debug-location !36
+    CMPri killed renamable $r0, 0, 14, $noreg, implicit-def $cpsr, debug-location !38
+    Bcc %bb.2, 0, killed $cpsr, debug-location !38
+
+  bb.1:
+    liveins: $r4
+
+    $r0 = MOVr $r4, 14, $noreg, $noreg, debug-location !41
+    BL @ext, csr_aapcs, implicit-def dead $lr, implicit $sp, implicit killed $r0, implicit-def $sp, debug-location !41
+    B %bb.1, debug-location !43
+
+  bb.2:
+    $r0 = MOVi 205, 14, $noreg, $noreg
+    $r0 = ORRri killed $r0, 43776, 14, $noreg, $noreg
+    $sp = LDMIA_UPD $sp, 14, $noreg, def $r4, def $r10, def $r11, def $lr, debug-location !46
+    TAILJMPd @ext, implicit $sp, implicit $sp, implicit killed $r0, debug-location !46
+
+...
+
+# In this test case the second parameter's value has been propagated from the
+# caller to the callee, so we should not emit any entry value DBG_VALUEs for
+# that parameter. The second parameter reuses the first parameter's register
+# ($r0), and previously we would incorrectly emit an entry value for the
+# parameter using that register.
+
+# CHECK-DAG: ![[P1:[0-9]+]] = !DILocalVariable(name: "p1", arg: 1
+# CHECK-DAG: ![[P2:[0-9]+]] = !DILocalVariable(name: "p2", arg: 2
+
+# CHECK-NOT: DBG_VALUE $r0, $noreg, ![[P2]], !DIExpression(DW_OP_LLVM_entry_value
+
+# CHECK: DBG_VALUE $r0, $noreg, ![[P1]], !DIExpression(DW_OP_LLVM_entry_value
+
+# CHECK-NOT: DBG_VALUE $r0, $noreg, ![[P2]], !DIExpression(DW_OP_LLVM_entry_value