diff --git a/lib/CodeGen/AsmPrinter/DIE.cpp b/lib/CodeGen/AsmPrinter/DIE.cpp
index 334c1083161..69444285f4e 100644
--- a/lib/CodeGen/AsmPrinter/DIE.cpp
+++ b/lib/CodeGen/AsmPrinter/DIE.cpp
@@ -115,13 +115,21 @@ DIE::~DIE() {
 /// Climb up the parent chain to get the compile unit DIE to which this DIE
 /// belongs.
 const DIE *DIE::getCompileUnit() const {
+  const DIE *Cu = getCompileUnitOrNull();
+  assert(Cu && "We should not have orphaned DIEs.");
+  return Cu;
+}
+
+/// Climb up the parent chain to get the compile unit DIE this DIE belongs
+/// to. Return NULL if DIE is not added to an owner yet.
+const DIE *DIE::getCompileUnitOrNull() const {
   const DIE *p = this;
   while (p) {
     if (p->getTag() == dwarf::DW_TAG_compile_unit)
       return p;
     p = p->getParent();
   }
-  llvm_unreachable("We should not have orphaned DIEs.");
+  return NULL;
 }
 
 DIEValue *DIE::findAttribute(uint16_t Attribute) {
diff --git a/lib/CodeGen/AsmPrinter/DIE.h b/lib/CodeGen/AsmPrinter/DIE.h
index 96a01327f76..f4fa326ef67 100644
--- a/lib/CodeGen/AsmPrinter/DIE.h
+++ b/lib/CodeGen/AsmPrinter/DIE.h
@@ -149,6 +149,9 @@ namespace llvm {
     /// Climb up the parent chain to get the compile unit DIE this DIE belongs
     /// to.
     const DIE *getCompileUnit() const;
+    /// Similar to getCompileUnit, returns null when DIE is not added to an
+    /// owner yet.
+    const DIE *getCompileUnitOrNull() const;
     void setOffset(unsigned O) { Offset = O; }
     void setSize(unsigned S) { Size = S; }
 
diff --git a/lib/CodeGen/AsmPrinter/DwarfCompileUnit.cpp b/lib/CodeGen/AsmPrinter/DwarfCompileUnit.cpp
index 703e2c12d8d..575cf31eaa6 100644
--- a/lib/CodeGen/AsmPrinter/DwarfCompileUnit.cpp
+++ b/lib/CodeGen/AsmPrinter/DwarfCompileUnit.cpp
@@ -98,6 +98,35 @@ int64_t CompileUnit::getDefaultLowerBound() const {
   return -1;
 }
 
+/// Check whether the DIE for this MDNode can be shared across CUs.
+static bool isShareableAcrossCUs(const MDNode *N) {
+  // When the MDNode can be part of the type system, the DIE can be
+  // shared across CUs.
+  return DIDescriptor(N).isType() ||
+         (DIDescriptor(N).isSubprogram() && !DISubprogram(N).isDefinition());
+}
+
+/// getDIE - Returns the debug information entry map slot for the
+/// specified debug variable. We delegate the request to DwarfDebug
+/// when the DIE for this MDNode can be shared across CUs. The mappings
+/// will be kept in DwarfDebug for shareable DIEs.
+DIE *CompileUnit::getDIE(const MDNode *N) const {
+  if (isShareableAcrossCUs(N))
+    return DD->getDIE(N);
+  return MDNodeToDieMap.lookup(N);
+}
+
+/// insertDIE - Insert DIE into the map. We delegate the request to DwarfDebug
+/// when the DIE for this MDNode can be shared across CUs. The mappings
+/// will be kept in DwarfDebug for shareable DIEs.
+void CompileUnit::insertDIE(const MDNode *N, DIE *D) {
+  if (isShareableAcrossCUs(N)) {
+    DD->insertDIE(N, D);
+    return;
+  }
+  MDNodeToDieMap.insert(std::make_pair(N, D));
+}
+
 /// addFlag - Add a flag that is true.
 void CompileUnit::addFlag(DIE *Die, dwarf::Attribute Attribute) {
   if (DD->getDwarfVersion() >= 4)
@@ -245,8 +274,21 @@ void CompileUnit::addDelta(DIE *Die, dwarf::Attribute Attribute, dwarf::Form For
 /// addDIEEntry - Add a DIE attribute data and value.
 ///
 void CompileUnit::addDIEEntry(DIE *Die, dwarf::Attribute Attribute, DIE *Entry) {
-  // We currently only use ref4.
-  Die->addValue(Attribute, dwarf::DW_FORM_ref4, createDIEEntry(Entry));
+  addDIEEntry(Die, Attribute, createDIEEntry(Entry));
+}
+
+void CompileUnit::addDIEEntry(DIE *Die, dwarf::Attribute Attribute,
+                              DIEEntry *Entry) {
+  const DIE *DieCU = Die->getCompileUnitOrNull();
+  const DIE *EntryCU = Entry->getEntry()->getCompileUnitOrNull();
+  if (!DieCU)
+    // We assume that Die belongs to this CU, if it is not linked to any CU yet.
+    DieCU = getCUDie();
+  if (!EntryCU)
+    EntryCU = getCUDie();
+  Die->addValue(Attribute, EntryCU == DieCU ? dwarf::DW_FORM_ref4
+                                            : dwarf::DW_FORM_ref_addr,
+                Entry);
 }
 
 /// Create a DIE with the given Tag, add the DIE to its parent, and
@@ -882,7 +924,7 @@ void CompileUnit::addType(DIE *Entity, DIType Ty, dwarf::Attribute Attribute) {
   DIEEntry *Entry = getDIEEntry(Ty);
   // If it exists then use the existing value.
   if (Entry) {
-    Entity->addValue(Attribute, dwarf::DW_FORM_ref4, Entry);
+    addDIEEntry(Entity, Attribute, Entry);
     return;
   }
 
@@ -892,7 +934,7 @@ void CompileUnit::addType(DIE *Entity, DIType Ty, dwarf::Attribute Attribute) {
   // Set up proxy.
   Entry = createDIEEntry(Buffer);
   insertDIEEntry(Ty, Entry);
-  Entity->addValue(Attribute, dwarf::DW_FORM_ref4, Entry);
+  addDIEEntry(Entity, Attribute, Entry);
 
   // If this is a complete composite type then include it in the
   // list of global types.
diff --git a/lib/CodeGen/AsmPrinter/DwarfCompileUnit.h b/lib/CodeGen/AsmPrinter/DwarfCompileUnit.h
index 8e2d69de727..a177d1910ba 100644
--- a/lib/CodeGen/AsmPrinter/DwarfCompileUnit.h
+++ b/lib/CodeGen/AsmPrinter/DwarfCompileUnit.h
@@ -155,15 +155,19 @@ public:
   void addAccelType(StringRef Name, std::pair<DIE *, unsigned> Die);
 
   /// getDIE - Returns the debug information entry map slot for the
-  /// specified debug variable.
-  DIE *getDIE(const MDNode *N) const { return MDNodeToDieMap.lookup(N); }
+  /// specified debug variable. We delegate the request to DwarfDebug
+  /// when the MDNode can be part of the type system, since DIEs for
+  /// the type system can be shared across CUs and the mappings are
+  /// kept in DwarfDebug.
+  DIE *getDIE(const MDNode *N) const;
 
   DIEBlock *getDIEBlock() { return new (DIEValueAllocator) DIEBlock(); }
 
-  /// insertDIE - Insert DIE into the map.
-  void insertDIE(const MDNode *N, DIE *D) {
-    MDNodeToDieMap.insert(std::make_pair(N, D));
-  }
+  /// insertDIE - Insert DIE into the map. We delegate the request to DwarfDebug
+  /// when the MDNode can be part of the type system, since DIEs for
+  /// the type system can be shared across CUs and the mappings are
+  /// kept in DwarfDebug.
+  void insertDIE(const MDNode *N, DIE *D);
 
   /// addDie - Adds or interns the DIE to the compile unit.
   ///
@@ -224,6 +228,10 @@ public:
   ///
   void addDIEEntry(DIE *Die, dwarf::Attribute Attribute, DIE *Entry);
 
+  /// addDIEEntry - Add a DIE attribute data and value.
+  ///
+  void addDIEEntry(DIE *Die, dwarf::Attribute Attribute, DIEEntry *Entry);
+
   /// addBlock - Add block data.
   ///
   void addBlock(DIE *Die, dwarf::Attribute Attribute, DIEBlock *Block);
diff --git a/lib/CodeGen/AsmPrinter/DwarfDebug.cpp b/lib/CodeGen/AsmPrinter/DwarfDebug.cpp
index 771cb3215a3..d18b7a55d31 100644
--- a/lib/CodeGen/AsmPrinter/DwarfDebug.cpp
+++ b/lib/CodeGen/AsmPrinter/DwarfDebug.cpp
@@ -2083,6 +2083,9 @@ void DwarfDebug::emitDIE(DIE *Die, ArrayRef<DIEAbbrev *> Abbrevs) {
                                          DwarfInfoSectionSym,
                                          DIEEntry::getRefAddrSize(Asm));
       } else {
+        // Make sure Origin belong to the same CU.
+        assert(Die->getCompileUnit() == Origin->getCompileUnit() &&
+               "The referenced DIE should belong to the same CU in ref4");
         Asm->EmitInt32(Addr);
       }
       break;
diff --git a/lib/CodeGen/AsmPrinter/DwarfDebug.h b/lib/CodeGen/AsmPrinter/DwarfDebug.h
index 90ca2763e6b..84fdcdd75e9 100644
--- a/lib/CodeGen/AsmPrinter/DwarfDebug.h
+++ b/lib/CodeGen/AsmPrinter/DwarfDebug.h
@@ -332,6 +332,11 @@ class DwarfDebug {
   // Maps a CU DIE with its corresponding CompileUnit.
   DenseMap <const DIE *, CompileUnit *> CUDieMap;
 
+  /// Maps MDNodes for type sysstem with the corresponding DIEs. These DIEs can
+  /// be shared across CUs, that is why we keep the map here instead
+  /// of in CompileUnit.
+  DenseMap<const MDNode *, DIE *> MDTypeNodeToDieMap;
+
   // Used to uniquely define abbreviations.
   FoldingSet<DIEAbbrev> AbbreviationsSet;
 
@@ -662,6 +667,13 @@ public:
   //
   DwarfDebug(AsmPrinter *A, Module *M);
 
+  void insertDIE(const MDNode *TypeMD, DIE *Die) {
+    MDTypeNodeToDieMap.insert(std::make_pair(TypeMD, Die));
+  }
+  DIE *getDIE(const MDNode *TypeMD) {
+    return MDTypeNodeToDieMap.lookup(TypeMD);
+  }
+
   /// \brief Emit all Dwarf sections that should come prior to the
   /// content.
   void beginModule();
diff --git a/test/DebugInfo/X86/ref_addr_relocation.ll b/test/DebugInfo/X86/ref_addr_relocation.ll
new file mode 100644
index 00000000000..3c1221fcbae
--- /dev/null
+++ b/test/DebugInfo/X86/ref_addr_relocation.ll
@@ -0,0 +1,70 @@
+; RUN: llc -filetype=asm -O0 -mtriple=x86_64-linux-gnu < %s | FileCheck %s
+; RUN: llc -filetype=obj -O0 %s -mtriple=x86_64-linux-gnu -o %t
+; RUN: llvm-dwarfdump %t | FileCheck %s -check-prefix=CHECK-DWARF
+
+; RUN: llc -filetype=obj %s -mtriple=x86_64-apple-darwin -o %t2
+; RUN: llvm-dwarfdump %t2 | FileCheck %s -check-prefix=DARWIN-DWARF
+
+; Testing case generated from:
+; clang++ tu1.cpp tu2.cpp -g -emit-llvm -c
+; llvm-link tu1.bc tu2.bc -o tu12.ll -S
+; cat hdr.h
+; struct foo {
+; };
+; cat tu1.cpp
+; #include "hdr.h"
+; foo f;
+; cat tu2.cpp
+; #include "hdr.h"
+; foo g;
+
+; Make sure we use relocation for ref_addr on non-darwin platforms.
+; CHECK: DW_TAG_compile_unit
+; CHECK: DW_TAG_variable
+; CHECK: .long [[TYPE:.*]] # DW_AT_type
+; CHECK: DW_TAG_structure_type
+; CHECK: debug_info_end0
+; CHECK: DW_TAG_compile_unit
+; CHECK-NOT: DW_TAG_structure_type
+; This variable's type is in the 1st CU.
+; CHECK: DW_TAG_variable
+; Make sure this is relocatable.
+; CHECK: .quad .Lsection_info+[[TYPE]] # DW_AT_type
+; CHECK-NOT: DW_TAG_structure_type
+; CHECK: debug_info_end1
+
+; CHECK-DWARF: DW_TAG_compile_unit
+; CHECK-DWARF: 0x[[ADDR:.*]]: DW_TAG_structure_type
+; CHECK-DWARF: DW_TAG_compile_unit
+; CHECK-DWARF: DW_TAG_variable
+; CHECK-DWARF: DW_AT_type [DW_FORM_ref_addr] {{.*}}[[ADDR]])
+
+; DARWIN-DWARF: DW_TAG_compile_unit
+; DARWIN-DWARF: 0x[[ADDR:.*]]: DW_TAG_structure_type
+; DARWIN-DWARF: DW_TAG_compile_unit
+; DARWIN-DWARF: DW_TAG_variable
+; DARWIN-DWARF: DW_AT_type [DW_FORM_ref_addr] {{.*}}[[ADDR]])
+
+%struct.foo = type { i8 }
+
+@f = global %struct.foo zeroinitializer, align 1
+@g = global %struct.foo zeroinitializer, align 1
+
+!llvm.dbg.cu = !{!0, !9}
+!llvm.module.flags = !{!14}
+
+!0 = metadata !{i32 786449, metadata !1, i32 4, metadata !"clang version 3.4 (trunk 191799)", i1 false, metadata !"", i32 0, metadata !2, metadata !3, metadata !2, metadata !6, metadata !2, metadata !""} ; [ DW_TAG_compile_unit ] [/Users/manmanren/test-Nov/type_unique_air/ref_addr/tu1.cpp] [DW_LANG_C_plus_plus]
+!1 = metadata !{metadata !"tu1.cpp", metadata !"/Users/manmanren/test-Nov/type_unique_air/ref_addr"}
+!2 = metadata !{i32 0}
+!3 = metadata !{metadata !4}
+!4 = metadata !{i32 786451, metadata !5, null, metadata !"foo", i32 1, i64 8, i64 8, i32 0, i32 0, null, metadata !2, i32 0, null, null, metadata !"_ZTS3foo"} ; [ DW_TAG_structure_type ] [foo] [line 1, size 8, align 8, offset 0] [def] [from ]
+!5 = metadata !{metadata !"./hdr.h", metadata !"/Users/manmanren/test-Nov/type_unique_air/ref_addr"}
+!6 = metadata !{metadata !7}
+!7 = metadata !{i32 786484, i32 0, null, metadata !"f", metadata !"f", metadata !"", metadata !8, i32 2, metadata !4, i32 0, i32 1, %struct.foo* @f, null} ; [ DW_TAG_variable ] [f] [line 2] [def]
+!8 = metadata !{i32 786473, metadata !1}          ; [ DW_TAG_file_type ] [/Users/manmanren/test-Nov/type_unique_air/ref_addr/tu1.cpp]
+!9 = metadata !{i32 786449, metadata !10, i32 4, metadata !"clang version 3.4 (trunk 191799)", i1 false, metadata !"", i32 0, metadata !2, metadata !3, metadata !2, metadata !11, metadata !2, metadata !""} ; [ DW_TAG_compile_unit ] [/Users/manmanren/test-Nov/type_unique_air/ref_addr/tu2.cpp] [DW_LANG_C_plus_plus]
+!10 = metadata !{metadata !"tu2.cpp", metadata !"/Users/manmanren/test-Nov/type_unique_air/ref_addr"}
+!11 = metadata !{metadata !12}
+!12 = metadata !{i32 786484, i32 0, null, metadata !"g", metadata !"g", metadata !"", metadata !13, i32 2, metadata !4, i32 0, i32 1, %struct.foo* @g, null} ; [ DW_TAG_variable ] [g] [line 2] [def]
+!13 = metadata !{i32 786473, metadata !10}        ; [ DW_TAG_file_type ] [/Users/manmanren/test-Nov/type_unique_air/ref_addr/tu2.cpp]
+!14 = metadata !{i32 2, metadata !"Dwarf Version", i32 2}
diff --git a/test/Linker/Inputs/type-unique-simple2-a.ll b/test/Linker/Inputs/type-unique-simple2-a.ll
index 20cfd545053..50581267d57 100644
--- a/test/Linker/Inputs/type-unique-simple2-a.ll
+++ b/test/Linker/Inputs/type-unique-simple2-a.ll
@@ -1,14 +1,18 @@
-; CHECK: 0x[[INT:.*]]: DW_TAG_base_type
-; CHECK-NEXT: DW_AT_name {{.*}} = "int"
-; CHECK-NOT: DW_TAG_base_type
+; Make sure the backend generates a single DIE and uses ref_addr.
 ; CHECK: 0x[[BASE:.*]]: DW_TAG_structure_type
 ; CHECK-NEXT: DW_AT_name {{.*}} = "Base"
 ; CHECK-NOT: DW_TAG_structure_type
+; CHECK: 0x[[INT:.*]]: DW_TAG_base_type
+; CHECK-NEXT: DW_AT_name {{.*}} = "int"
+; CHECK-NOT: DW_TAG_base_type
+
+; CHECK: DW_TAG_compile_unit
 ; CHECK: DW_TAG_formal_parameter
 ; CHECK: DW_AT_type [DW_FORM_ref_addr] {{.*}}[[INT]])
 ; CHECK: DW_TAG_variable
 ; CHECK: DW_AT_type [DW_FORM_ref_addr] {{.*}}[[BASE]])
 
+; Make sure llvm-link only generates a single copy of the struct.
 ; LINK: DW_TAG_structure_type
 ; LINK-NOT: DW_TAG_structure_type
 
diff --git a/test/Linker/type-unique-simple-a.ll b/test/Linker/type-unique-simple-a.ll
index c8f9462d80d..808563f2939 100644
--- a/test/Linker/type-unique-simple-a.ll
+++ b/test/Linker/type-unique-simple-a.ll
@@ -1,7 +1,27 @@
-; RUN: llvm-link %s %p/type-unique-simple-b.ll -S -o - | FileCheck %s
+; REQUIRES: object-emission
 
-; CHECK: DW_TAG_structure_type
+; RUN: llvm-link %s %p/type-unique-simple-b.ll -S -o %t
+; RUN: cat %t | FileCheck %s -check-prefix=LINK
+; RUN: llc -filetype=obj -O0 < %t > %t2
+; RUN: llvm-dwarfdump -debug-dump=info %t2 | FileCheck %s
+
+; Make sure the backend generates a single DIE and uses ref_addr.
+; CHECK: 0x[[BASE:.*]]: DW_TAG_structure_type
+; CHECK-NEXT: DW_AT_name {{.*}} = "Base"
 ; CHECK-NOT: DW_TAG_structure_type
+; CHECK: 0x[[INT:.*]]: DW_TAG_base_type
+; CHECK-NEXT: DW_AT_name {{.*}} = "int"
+; CHECK-NOT: DW_TAG_base_type
+
+; CHECK: DW_TAG_compile_unit
+; CHECK: DW_TAG_formal_parameter
+; CHECK: DW_AT_type [DW_FORM_ref_addr] {{.*}}[[INT]])
+; CHECK: DW_TAG_variable
+; CHECK: DW_AT_type [DW_FORM_ref_addr] {{.*}}[[BASE]])
+
+; Make sure llvm-link only generates a single copy of the struct.
+; LINK: DW_TAG_structure_type
+; LINK-NOT: DW_TAG_structure_type
 ; Content of header files:
 ; struct Base {
 ;   int a;
diff --git a/test/Linker/type-unique-simple2.ll b/test/Linker/type-unique-simple2.ll
index 83e4715bf0d..ead91df6da1 100644
--- a/test/Linker/type-unique-simple2.ll
+++ b/test/Linker/type-unique-simple2.ll
@@ -2,3 +2,5 @@
 
 ; RUN: llvm-link %S/Inputs/type-unique-simple2-a.ll %S/Inputs/type-unique-simple2-b.ll -S -o %t
 ; RUN: cat %t | FileCheck %S/Inputs/type-unique-simple2-a.ll -check-prefix=LINK
+; RUN: llc -filetype=obj -O0 < %t > %t2
+; RUN: llvm-dwarfdump -debug-dump=info %t2 | FileCheck %S/Inputs/type-unique-simple2-a.ll