Index: llvm/include/llvm/IR/DebugInfoMetadata.h
===================================================================
--- llvm/include/llvm/IR/DebugInfoMetadata.h
+++ llvm/include/llvm/IR/DebugInfoMetadata.h
@@ -2468,6 +2468,9 @@
   /// it cannot be a simple register location.
   bool isComplex() const;
 
+  ///  Return whether this is an operation with a constant offset.
+  bool isOpWithOffset() const;
+
   /// Append \p Ops with operations to apply the \p Offset.
   static void appendOffset(SmallVectorImpl<uint64_t> &Ops, int64_t Offset);
 
Index: llvm/lib/CodeGen/AsmPrinter/DwarfExpression.cpp
===================================================================
--- llvm/lib/CodeGen/AsmPrinter/DwarfExpression.cpp
+++ llvm/lib/CodeGen/AsmPrinter/DwarfExpression.cpp
@@ -246,8 +246,8 @@
   // a call site parameter expression and if that expression is just a register
   // location, emit it with addBReg and offset 0, because we should emit a DWARF
   // expression representing a value, rather than a location.
-  if (!isMemoryLocation() && !HasComplexExpression &&
-      (!isParameterValue() || isEntryValue())) {
+  if ((!isMemoryLocation() && !HasComplexExpression && !isParameterValue()) ||
+      isEntryValue()) {
     for (auto &Reg : DwarfRegs) {
       if (Reg.DwarfRegNo >= 0)
         addReg(Reg.DwarfRegNo, Reg.Comment);
@@ -257,8 +257,8 @@
     if (isEntryValue())
       finalizeEntryValue();
 
-    if (isEntryValue() && !isParameterValue() && DwarfVersion >= 4)
-      emitOp(dwarf::DW_OP_stack_value);
+    if (isEntryValue() && !isParameterValue() && isRegisterLocation())
+      LocationKind = Implicit;
 
     DwarfRegs.clear();
     return true;
Index: llvm/lib/CodeGen/LiveDebugValues.cpp
===================================================================
--- llvm/lib/CodeGen/LiveDebugValues.cpp
+++ llvm/lib/CodeGen/LiveDebugValues.cpp
@@ -411,9 +411,16 @@
     // A copy like instruction that moves the entry value around.
     MachineInstr *DbgEntryValueMovement;
 
+    // A debug info expression describing the debug entry value modification.
+    DIExpression *DbgEntryValueModification;
+
     void setDbgEntryValueMovement(MachineInstr *MI) {
       DbgEntryValueMovement = MI;
     }
+
+    void setDbgEntryValueModification(DIExpression *Expr) {
+      DbgEntryValueModification = Expr;
+    }
   };
   using DebugParamMap = SmallDenseMap<const DILocalVariable *, EntryValue>;
 
@@ -740,6 +747,17 @@
         MI.getOperand(0).getReg() == EntryValueCopyReg) {
       if (MI.getDebugExpression()->getNumElements() == 0)
         return;
+      else if (Expr->isOpWithOffset()) {
+        // Handle the debug entry value modification.
+        DIExpression *NewEntryValExpr =
+            DebugEntryVals[Var].DbgEntryValueModification;
+        NewEntryValExpr =
+            DIExpression::prepend(Expr, DIExpression::ApplyOffset);
+        DebugEntryVals[Var].setDbgEntryValueModification(NewEntryValExpr);
+        return;
+      }
+      // Stop tracking the entry value.
+      DebugEntryVals.erase(Var);
     }
   }
 
@@ -821,6 +839,16 @@
     DIExpression *NewExpr = DIExpression::prepend(
         ParamDebugInstr->getDebugExpression(), DIExpression::EntryValue);
 
+    // Follow the modification of the debug entry value if any.
+    DIExpression *EntryValModification =
+        ParamEntryValue->second.DbgEntryValueModification;
+    if (EntryValModification->getNumElements() != 0) {
+      ArrayRef<uint64_t> elements = NewExpr->getElements();
+      SmallVector<uint64_t, 16> Ops;
+      Ops.append(elements.begin(), elements.end());
+      NewExpr = DIExpression::prependOpcodes(EntryValModification, Ops);
+    }
+
     auto getEntryLoc = [ParamDebugInstr, ParamEntryValMovement,
                         NewExpr](LexicalScopes &LS) {
       if (ParamEntryValMovement)
@@ -1438,8 +1466,6 @@
   // unmodified throughout the function and located in a register.
   // TODO: Add support for parameters with non-empty debug expressions (for
   // example fragments).
-  // TODO: Add support for modified arguments that can be expressed
-  // by using its entry value.
   // TODO: Add support for local variables that are expressed in terms of
   // parameters entry values.
   for (auto &MI : First_MBB)
@@ -1448,8 +1474,12 @@
         !MI.isIndirectDebugValue() &&
         isRegOtherThanSPAndFP(MI.getOperand(0), MI, TRI) &&
         !DebugEntryVals.count(MI.getDebugVariable()) &&
-        MI.getDebugExpression()->getNumElements() == 0)
-      DebugEntryVals[MI.getDebugVariable()] = EntryValue{&MI, nullptr};
+        MI.getDebugExpression()->getNumElements() == 0) {
+      DIExpression *EntryValueModificationExpr =
+          DIExpression::get(MF.getFunction().getContext(), {});
+      DebugEntryVals[MI.getDebugVariable()] =
+          EntryValue{&MI, nullptr, EntryValueModificationExpr};
+    }
 
   // Initialize per-block structures and scan for fragment overlaps.
   for (auto &MBB : MF) {
Index: llvm/lib/IR/DebugInfoMetadata.cpp
===================================================================
--- llvm/lib/IR/DebugInfoMetadata.cpp
+++ llvm/lib/IR/DebugInfoMetadata.cpp
@@ -896,8 +896,7 @@
       // entry values of a simple register location. One reason for this is that
       // we currently can't calculate the size of the resulting DWARF block for
       // other expressions.
-      return I->get() == expr_op_begin()->get() && I->getArg(0) == 1 &&
-             getNumElements() == 2;
+      return I->get() == expr_op_begin()->get() && I->getArg(0) == 1;
     }
     case dwarf::DW_OP_LLVM_convert:
     case dwarf::DW_OP_LLVM_tag_offset:
@@ -964,6 +963,21 @@
   return false;
 }
 
+bool DIExpression::isOpWithOffset() const {
+  if (getNumElements() == 0)
+    return false;
+
+  if (getNumElements() == 3 && Elements[0] == dwarf::DW_OP_plus_uconst)
+    return true;
+
+  if (getNumElements() == 4 && Elements[0] == dwarf::DW_OP_constu)
+    if (Elements[2] == dwarf::DW_OP_plus ||
+        Elements[2] == dwarf::DW_OP_minus)
+      return true;
+
+  return false;
+}
+
 Optional<DIExpression::FragmentInfo>
 DIExpression::getFragmentInfo(expr_op_iterator Start, expr_op_iterator End) {
   for (auto I = Start; I != End; ++I)
Index: llvm/test/DebugInfo/MIR/X86/entry-value-of-modified-param.mir
===================================================================
--- llvm/test/DebugInfo/MIR/X86/entry-value-of-modified-param.mir
+++ llvm/test/DebugInfo/MIR/X86/entry-value-of-modified-param.mir
@@ -19,7 +19,7 @@
 # CHECK: DBG_VALUE $edi, $noreg, !16, !DIExpression(DW_OP_LLVM_entry_value, 1), debug-location {{.*}}
 # CHECK: DBG_VALUE $edx, $noreg, !18, !DIExpression(DW_OP_LLVM_entry_value, 1), debug-location {{.*}}
 # CHECK: DBG_VALUE $edi, $noreg, !16, !DIExpression(DW_OP_LLVM_entry_value, 1), debug-location {{.*}}
-# CHECK-NOT: DBG_VALUE $esi, $noreg, !17, !DIExpression(DW_OP_LLVM_entry_value, 1, DW_OP_plus_uconst, 7, DW_OP_stack_value), debug-location {{.*}}
+# CHECK: DBG_VALUE $esi, $noreg, !17, !DIExpression(DW_OP_LLVM_entry_value, 1, DW_OP_plus_uconst, 7, DW_OP_stack_value), debug-location {{.*}}
 #
 --- |
   ; ModuleID = 'test.c'