Index: ELF/Driver.cpp
===================================================================
--- ELF/Driver.cpp
+++ ELF/Driver.cpp
@@ -17,6 +17,7 @@
 #include "llvm/ADT/StringExtras.h"
 #include "llvm/Support/FileSystem.h"
 #include "llvm/Support/Path.h"
+#include "llvm/Support/StringSaver.h"
 
 using namespace llvm;
 using namespace llvm::ELF;
@@ -225,6 +226,14 @@
   if (Config->OutputFile.empty())
     Config->OutputFile = "a.out";
 
+  llvm::BumpPtrAllocator Alloc;
+  llvm::StringSaver Saver(Alloc);
+
+  for (auto *Arg : Args.filtered(OPT_wrap)) {
+    StringRef Sym = Arg->getValue();
+    Symtab.wrap(Sym, Saver.save("__wrap_" + Sym), Saver.save("__real_" + Sym));
+  }
+
   // Write the result.
   const ELFFileBase *FirstObj = Symtab.getFirstELF();
   switch (FirstObj->getELFKind()) {
Index: ELF/Options.td
===================================================================
--- ELF/Options.td
+++ ELF/Options.td
@@ -85,6 +85,9 @@
 def z : JoinedOrSeparate<["-"], "z">, MetaVarName<"<option>">,
   HelpText<"Linker option extensions">;
 
+def wrap : Separate<["--", "-"], "wrap">, MetaVarName<"<symbol>">,
+  HelpText<"Use a wrapper function for symbol">;
+
 // Aliases
 def alias_Bdynamic_call_shared: Flag<["-"], "call_shared">, Alias<Bdynamic>;
 def alias_Bdynamic_dy: Flag<["-"], "dy">, Alias<Bdynamic>;
@@ -102,6 +105,7 @@
 def alias_soname_h : Separate<["-"], "h">, Alias<soname>;
 def alias_soname_soname : Separate<["-"], "soname">, Alias<soname>;
 def alias_undefined_u : Separate<["-"], "u">, Alias<undefined>;
+def alias_wrap_wrap : Joined<["--", "-"], "wrap=">, Alias<wrap>;
 
 // Options listed below are silently ignored now.
 def O3 : Flag<["-"], "O3">;
Index: ELF/SymbolTable.h
===================================================================
--- ELF/SymbolTable.h
+++ ELF/SymbolTable.h
@@ -61,7 +61,8 @@
     return EntrySym->getReplacement();
   }
 
-  void addUndefinedSym(StringRef Name);
+  SymbolBody *addUndefinedSym(StringRef Name);
+  void wrap(StringRef Sym, StringRef Wrap, StringRef Real);
 
   template <class ELFT>
   void addSyntheticSym(StringRef Name, OutputSection<ELFT> &Section,
@@ -75,7 +76,7 @@
   void addELFFile(ELFFileBase *File);
   void addLazy(Lazy *New);
   void addMemberFile(Lazy *Body);
-  template <class ELFT> void addUndefinedSym(StringRef Name);
+  template <class ELFT> SymbolBody *addUndefinedSym(StringRef Name);
 
   template <class ELFT> void init(uint16_t EMachine);
   template <class ELFT> void resolve(SymbolBody *Body);
Index: ELF/SymbolTable.cpp
===================================================================
--- ELF/SymbolTable.cpp
+++ ELF/SymbolTable.cpp
@@ -70,29 +70,38 @@
   error("Unknown target machine");
 }
 
-void SymbolTable::addUndefinedSym(StringRef Name) {
+SymbolBody *SymbolTable::addUndefinedSym(StringRef Name) {
   switch (getFirstELF()->getELFKind()) {
   case ELF32LEKind:
-    addUndefinedSym<ELF32LE>(Name);
-    break;
+    return addUndefinedSym<ELF32LE>(Name);
   case ELF32BEKind:
-    addUndefinedSym<ELF32BE>(Name);
-    break;
+    return addUndefinedSym<ELF32BE>(Name);
   case ELF64LEKind:
-    addUndefinedSym<ELF64LE>(Name);
-    break;
+    return addUndefinedSym<ELF64LE>(Name);
   case ELF64BEKind:
-    addUndefinedSym<ELF64BE>(Name);
-    break;
+    return addUndefinedSym<ELF64BE>(Name);
   default:
     llvm_unreachable("Invalid kind");
   }
 }
 
-template <class ELFT> void SymbolTable::addUndefinedSym(StringRef Name) {
+template <class ELFT> SymbolBody *SymbolTable::addUndefinedSym(StringRef Name) {
   Undefined<ELFT>::SyntheticOptional.setVisibility(STV_HIDDEN);
-  resolve<ELFT>(new (Alloc)
-                    Undefined<ELFT>(Name, Undefined<ELFT>::SyntheticOptional));
+  auto *U = new (Alloc) Undefined<ELFT>(
+      Name, Undefined<ELFT>::SyntheticOptional);
+  resolve<ELFT>(U);
+  return U;
+}
+
+// Rename Real -> Sym and then Sym -> Wrap. Used for --wrap.
+void SymbolTable::wrap(StringRef Sym, StringRef Wrap, StringRef Real) {
+  if (Symtab.count(Sym) == 0)
+    return;
+  SymbolBody *S = addUndefinedSym(Sym);
+  SymbolBody *W = addUndefinedSym(Wrap);
+  SymbolBody *R = addUndefinedSym(Real);
+  R->setReplacement(S->getReplacement());
+  S->setReplacement(W->getReplacement());
 }
 
 template <class ELFT>
Index: ELF/Symbols.h
===================================================================
--- ELF/Symbols.h
+++ ELF/Symbols.h
@@ -87,6 +87,7 @@
   // has chosen the object among other objects having the same name,
   // you can access P->Backref->Body to get the resolver's result.
   void setBackref(Symbol *P) { Backref = P; }
+  void setReplacement(SymbolBody *B) { Backref->Body = B; }
   SymbolBody *getReplacement() { return Backref ? Backref->Body : this; }
 
   // Decides which symbol should "win" in the symbol table, this or
Index: test/elf2/Inputs/wrap.s
===================================================================
--- /dev/null
+++ test/elf2/Inputs/wrap.s
@@ -0,0 +1,4 @@
+.globl foo,__wrap_foo,__real_foo;
+foo        = 0x11000
+__wrap_foo = 0x11010
+__real_foo = 0x11020
Index: test/elf2/wrap.s
===================================================================
--- /dev/null
+++ test/elf2/wrap.s
@@ -0,0 +1,19 @@
+// REQUIRES: x86
+// RUN: llvm-mc -filetype=obj -triple=x86_64-pc-linux %s -o %t
+// RUN: llvm-mc -filetype=obj -triple=x86_64-pc-linux %p/Inputs/wrap.s -o %t2
+
+// 1) Should replace used symbols foo -> __wrap_foo, __real_foo -> foo
+// 2) Should not fail on undefined symbol if it isn't used (bar)
+// RUN: lld -flavor gnu2 -o %t3 %t %t2 -wrap foo -wrap bar
+// RUN: llvm-objdump -d -print-imm-hex %t3 | FileCheck %s
+
+// CHECK: _start:
+// CHECK-NEXT: movl $0x11010, %edx
+// CHECK-NEXT: movl $0x11010, %edx
+// CHECK-NEXT: movl $0x11000, %edx
+
+.global _start;
+_start:
+  movl $foo, %edx
+  movl $__wrap_foo, %edx
+  movl $__real_foo, %edx
Index: test/elf2/wrap2.s
===================================================================
--- /dev/null
+++ test/elf2/wrap2.s
@@ -0,0 +1,31 @@
+// REQUIRES: x86
+// RUN: llvm-mc -filetype=obj -triple=x86_64-pc-linux %s -o %t
+
+// RUN: lld -flavor gnu2 -shared -o %t2 %t -wrap foo -wrap bar -wrap baz
+// RUN: llvm-readobj -symbols %t2 | FileCheck %s --check-prefix=CHECK1
+// RUN: llvm-readobj -symbols %t2 | FileCheck %s --check-prefix=CHECK2
+// Check aliases of the switch
+// RUN: lld -flavor gnu2 -shared -o %t2 %t --wrap foo -wrap=bar --wrap=baz
+// RUN: llvm-readobj -symbols %t2 | FileCheck %s --check-prefix=CHECK1
+// RUN: llvm-readobj -symbols %t2 | FileCheck %s --check-prefix=CHECK2
+
+// CHECK1: Symbols [
+// CHECK1-DAG: Name: __wrap_foo
+// CHECK1-DAG: Name: bar
+// CHECK1-DAG: Name: __wrap_baz
+// CHECK1: ]
+
+// CHECK2: Symbols [
+// CHECK2-NOT: Name: foo
+// CHECK2-NOT: Name: __real_foo
+// CHECK2-NOT: Name: __wrap_bar
+// CHECK2-NOT: Name: __real_bar
+// CHECK2-NOT: Name: baz
+// CHECK2-NOT: Name: __real_baz
+// CHECK2: ]
+
+.global _start;
+_start:
+  jmp foo@PLT
+  jmp __real_bar@PLT
+  jmp __wrap_baz@PLT