diff --git a/llvm/lib/CodeGen/AsmPrinter/DwarfCompileUnit.cpp b/llvm/lib/CodeGen/AsmPrinter/DwarfCompileUnit.cpp
index 7e147e8466ae..6a8c9b5e43fe 100644
--- a/llvm/lib/CodeGen/AsmPrinter/DwarfCompileUnit.cpp
+++ b/llvm/lib/CodeGen/AsmPrinter/DwarfCompileUnit.cpp
@@ -516,15 +516,21 @@ DwarfCompileUnit::constructVariableDIEImpl(const DbgVariable &DV,
   }
 
   // .. else use frame index.
-  int FI = DV.getFrameIndex();
-  if (FI != ~0) {
+  if (DV.getFrameIndex().back() == ~0)
+    return VariableDie;
+
+  auto Expr = DV.getExpression().begin();
+  DIELoc *Loc = new (DIEValueAllocator) DIELoc();
+  DIEDwarfExpression DwarfExpr(*Asm, *this, *Loc);
+  for (auto FI : DV.getFrameIndex()) {
     unsigned FrameReg = 0;
     const TargetFrameLowering *TFI =
         Asm->TM.getSubtargetImpl()->getFrameLowering();
     int Offset = TFI->getFrameIndexReference(*Asm->MF, FI, FrameReg);
-    MachineLocation Location(FrameReg, Offset);
-    addVariableAddress(DV, *VariableDie, Location);
+    DwarfExpr.AddMachineRegIndirect(FrameReg, Offset);
+    DwarfExpr.AddExpression(*(Expr++));
   }
+  addBlock(*VariableDie, dwarf::DW_AT_location, Loc);
 
   return VariableDie;
 }
@@ -767,7 +773,8 @@ void DwarfCompileUnit::addComplexAddress(const DbgVariable &DV, DIE &Die,
                                          const MachineLocation &Location) {
   DIELoc *Loc = new (DIEValueAllocator) DIELoc();
   DIEDwarfExpression DwarfExpr(*Asm, *this, *Loc);
-  DIExpression Expr = DV.getExpression();
+  assert(DV.getExpression().size() == 1);
+  DIExpression Expr = DV.getExpression().back();
   bool ValidReg;
   if (Location.getOffset()) {
     ValidReg = DwarfExpr.AddMachineRegIndirect(Location.getReg(),
diff --git a/llvm/lib/CodeGen/AsmPrinter/DwarfDebug.cpp b/llvm/lib/CodeGen/AsmPrinter/DwarfDebug.cpp
index 8cb033a175ee..3b6f4614cac6 100644
--- a/llvm/lib/CodeGen/AsmPrinter/DwarfDebug.cpp
+++ b/llvm/lib/CodeGen/AsmPrinter/DwarfDebug.cpp
@@ -783,10 +783,9 @@ void DwarfDebug::collectVariableInfoFromMMITable(
     DIVariable DV(VI.Var);
     DIExpression Expr(VI.Expr);
     ensureAbstractVariableIsCreatedIfScoped(DV, Scope->getScopeNode());
-    ConcreteVariables.push_back(make_unique<DbgVariable>(DV, Expr, this));
-    DbgVariable *RegVar = ConcreteVariables.back().get();
-    RegVar->setFrameIndex(VI.Slot);
-    InfoHolder.addScopeVariable(Scope, RegVar);
+    auto RegVar = make_unique<DbgVariable>(DV, Expr, this, VI.Slot);
+    if (InfoHolder.addScopeVariable(Scope, RegVar.get()))
+      ConcreteVariables.push_back(std::move(RegVar));
   }
 }
 
diff --git a/llvm/lib/CodeGen/AsmPrinter/DwarfDebug.h b/llvm/lib/CodeGen/AsmPrinter/DwarfDebug.h
index a1a94264dddd..4755c9cd1b95 100644
--- a/llvm/lib/CodeGen/AsmPrinter/DwarfDebug.h
+++ b/llvm/lib/CodeGen/AsmPrinter/DwarfDebug.h
@@ -67,41 +67,66 @@ public:
 
 //===----------------------------------------------------------------------===//
 /// \brief This class is used to track local variable information.
+///
+/// - Variables whose location changes over time have a DotDebugLocOffset and the
+///   other fields are not used.
+///
+/// - Variables that are described by multiple MMI table entries have multiple
+///   expressions and frame indices.
 class DbgVariable {
-  DIVariable Var;             // Variable Descriptor.
-  DIExpression Expr;          // Complex address location expression.
-  DIE *TheDIE;                // Variable DIE.
-  unsigned DotDebugLocOffset; // Offset in DotDebugLocEntries.
-  const MachineInstr *MInsn;  // DBG_VALUE instruction of the variable.
-  int FrameIndex;
+  DIVariable Var;             /// Variable Descriptor.
+  SmallVector<DIExpression, 1> Expr; /// Complex address location expression.
+  DIE *TheDIE;                /// Variable DIE.
+  unsigned DotDebugLocOffset; /// Offset in DotDebugLocEntries.
+  const MachineInstr *MInsn;  /// DBG_VALUE instruction of the variable.
+  SmallVector<int, 1> FrameIndex; /// Frame index of the variable.
   DwarfDebug *DD;
 
 public:
   /// Construct a DbgVariable from a DIVariable.
-  DbgVariable(DIVariable V, DIExpression E, DwarfDebug *DD)
-      : Var(V), Expr(E), TheDIE(nullptr), DotDebugLocOffset(~0U),
-        MInsn(nullptr), FrameIndex(~0), DD(DD) {
-    assert(Var.Verify() && Expr.Verify());
+    DbgVariable(DIVariable V, DIExpression E, DwarfDebug *DD, int FI = ~0)
+    : Var(V), Expr(1, E), TheDIE(nullptr), DotDebugLocOffset(~0U),
+      MInsn(nullptr), DD(DD) {
+    FrameIndex.push_back(FI);
+    assert(Var.Verify() && E.Verify());
   }
 
   /// Construct a DbgVariable from a DEBUG_VALUE.
   /// AbstractVar may be NULL.
   DbgVariable(const MachineInstr *DbgValue, DwarfDebug *DD)
-      : Var(DbgValue->getDebugVariable()), Expr(DbgValue->getDebugExpression()),
-        TheDIE(nullptr), DotDebugLocOffset(~0U), MInsn(DbgValue),
-        FrameIndex(~0), DD(DD) {}
+    : Var(DbgValue->getDebugVariable()), Expr(1, DbgValue->getDebugExpression()),
+        TheDIE(nullptr), DotDebugLocOffset(~0U), MInsn(DbgValue), DD(DD) {
+    FrameIndex.push_back(~0);
+  }
 
   // Accessors.
   DIVariable getVariable() const { return Var; }
-  DIExpression getExpression() const { return Expr; }
+  const ArrayRef<DIExpression> getExpression() const { return Expr; }
   void setDIE(DIE &D) { TheDIE = &D; }
   DIE *getDIE() const { return TheDIE; }
   void setDotDebugLocOffset(unsigned O) { DotDebugLocOffset = O; }
   unsigned getDotDebugLocOffset() const { return DotDebugLocOffset; }
   StringRef getName() const { return Var.getName(); }
   const MachineInstr *getMInsn() const { return MInsn; }
-  int getFrameIndex() const { return FrameIndex; }
-  void setFrameIndex(int FI) { FrameIndex = FI; }
+  const ArrayRef<int> getFrameIndex() const { return FrameIndex; }
+
+  void addMMIEntry(const DbgVariable &V) {
+    assert(  DotDebugLocOffset == ~0U &&   !MInsn && "not an MMI entry");
+    assert(V.DotDebugLocOffset == ~0U && !V.MInsn && "not an MMI entry");
+    assert(V.Var == Var && "conflicting DIVariable");
+
+    if (V.getFrameIndex().back() != ~0) {
+      auto E = V.getExpression();
+      auto FI = V.getFrameIndex();
+      Expr.append(E.begin(), E.end());
+      FrameIndex.append(FI.begin(), FI.end());
+    }
+    assert(Expr.size() > 1
+           ? std::all_of(Expr.begin(), Expr.end(),
+                         [](DIExpression &E) { return E.isBitPiece(); })
+           : (true && "conflicting locations for variable"));
+  }
+
   // Translate tag to proper Dwarf tag.
   dwarf::Tag getTag() const {
     if (Var.getTag() == dwarf::DW_TAG_arg_variable)
@@ -128,14 +153,11 @@ public:
 
   bool variableHasComplexAddress() const {
     assert(Var.isVariable() && "Invalid complex DbgVariable!");
-    return Expr.getNumElements() > 0;
+    assert(Expr.size() == 1 &&
+           "variableHasComplexAddress() invoked on multi-FI variable");
+    return Expr.back().getNumElements() > 0;
   }
   bool isBlockByrefVariable() const;
-  unsigned getNumAddrElements() const {
-    assert(Var.isVariable() && "Invalid complex DbgVariable!");
-    return Expr.getNumElements();
-  }
-  uint64_t getAddrElement(unsigned i) const { return Expr.getElement(i); }
   DIType getType() const;
 
 private:
diff --git a/llvm/lib/CodeGen/AsmPrinter/DwarfFile.cpp b/llvm/lib/CodeGen/AsmPrinter/DwarfFile.cpp
index 408f683301d0..3988f0def317 100644
--- a/llvm/lib/CodeGen/AsmPrinter/DwarfFile.cpp
+++ b/llvm/lib/CodeGen/AsmPrinter/DwarfFile.cpp
@@ -146,7 +146,7 @@ void DwarfFile::emitStrings(const MCSection *StrSection,
   StrPool.emit(*Asm, StrSection, OffsetSection);
 }
 
-void DwarfFile::addScopeVariable(LexicalScope *LS, DbgVariable *Var) {
+bool DwarfFile::addScopeVariable(LexicalScope *LS, DbgVariable *Var) {
   SmallVectorImpl<DbgVariable *> &Vars = ScopeVariables[LS];
   DIVariable DV = Var->getVariable();
   // Variables with positive arg numbers are parameters.
@@ -168,13 +168,17 @@ void DwarfFile::addScopeVariable(LexicalScope *LS, DbgVariable *Var) {
       // A later indexed parameter has been found, insert immediately before it.
       if (CurNum > ArgNum)
         break;
-      assert(CurNum != ArgNum && "Duplicate argument");
+      if (CurNum == ArgNum) {
+        (*I)->addMMIEntry(*Var);
+        return false;
+      }
       ++I;
     }
     Vars.insert(I, Var);
-    return;
+    return true;
   }
 
   Vars.push_back(Var);
+  return true;
 }
 }
diff --git a/llvm/lib/CodeGen/AsmPrinter/DwarfFile.h b/llvm/lib/CodeGen/AsmPrinter/DwarfFile.h
index f14d673bf6ac..35bf33ab9581 100644
--- a/llvm/lib/CodeGen/AsmPrinter/DwarfFile.h
+++ b/llvm/lib/CodeGen/AsmPrinter/DwarfFile.h
@@ -95,7 +95,8 @@ public:
   /// \brief Returns the string pool.
   DwarfStringPool &getStringPool() { return StrPool; }
 
-  void addScopeVariable(LexicalScope *LS, DbgVariable *Var);
+  /// \returns false if the variable was merged with a previous one.
+  bool addScopeVariable(LexicalScope *LS, DbgVariable *Var);
 
   DenseMap<LexicalScope *, SmallVector<DbgVariable *, 8>> &getScopeVariables() {
     return ScopeVariables;