Index: include/lld/ReaderWriter/LinkerScript.h
===================================================================
--- include/lld/ReaderWriter/LinkerScript.h
+++ include/lld/ReaderWriter/LinkerScript.h
@@ -73,6 +73,7 @@
     kw_discard,
     kw_entry,
     kw_exclude_file,
+    kw_extern,
     kw_group,
     kw_hidden,
     kw_input,
@@ -154,6 +155,7 @@
 public:
   enum class Kind {
     Entry,
+    Extern,
     Group,
     Input,
     InputSectionsCmd,
@@ -841,6 +843,29 @@
   llvm::ArrayRef<const MemoryBlock *> _blocks;
 };
 
+/// Represents an extern command.
+class Extern : public Command {
+public:
+  Extern(Parser &ctx,
+         const SmallVectorImpl<StringRef> &symbols)
+      : Command(ctx, Kind::Extern) {
+    size_t numSymbols = symbols.size();
+    StringRef *symbolsStart =
+        getAllocator().Allocate<StringRef>(numSymbols);
+    std::copy(std::begin(symbols), std::end(symbols), symbolsStart);
+    _symbols = llvm::makeArrayRef(symbolsStart, numSymbols);
+  }
+
+  static bool classof(const Command *c) {
+    return c->getKind() == Kind::Extern;
+  }
+
+  void dump(raw_ostream &os) const override;
+
+private:
+  llvm::ArrayRef<StringRef> _symbols;
+};
+
 
 /// Stores the parse tree of a linker script.
 class LinkerScript {
@@ -1121,6 +1146,7 @@
   ///
   Memory *parseMemory();
 
+  Extern *parseExtern();
 private:
   // Owns the entire linker script AST nodes
   llvm::BumpPtrAllocator _alloc;
Index: lib/ReaderWriter/LinkerScript.cpp
===================================================================
--- lib/ReaderWriter/LinkerScript.cpp
+++ lib/ReaderWriter/LinkerScript.cpp
@@ -62,6 +62,7 @@
     CASE(kw_discard)
     CASE(kw_entry)
     CASE(kw_exclude_file)
+    CASE(kw_extern)
     CASE(kw_group)
     CASE(kw_hidden)
     CASE(kw_input)
@@ -467,6 +468,7 @@
             .Case("AT", Token::kw_at)
             .Case("ENTRY", Token::kw_entry)
             .Case("EXCLUDE_FILE", Token::kw_exclude_file)
+            .Case("EXTERN", Token::kw_extern)
             .Case("GROUP", Token::kw_group)
             .Case("HIDDEN", Token::kw_hidden)
             .Case("INPUT", Token::kw_input)
@@ -952,6 +954,18 @@
   os << "}\n";
 }
 
+// Extern functions
+void Extern::dump(raw_ostream &os) const {
+  os << "EXTERN(";
+  for (unsigned i = 0, e = _symbols.size(); i != e; ++i) {
+    if (i)
+      os << " ";
+    os << _symbols[i];
+  }
+  os << ")\n";
+}
+
+
 // Parser functions
 std::error_code Parser::parse() {
   // Get the first token.
@@ -1041,6 +1055,13 @@
       _script._commands.push_back(cmd);
       break;
     }
+    case Token::kw_extern: {
+      const Command *cmd = parseExtern();
+      if (!cmd)
+        return LinkerScriptReaderError::parse_error;
+      _script._commands.push_back(cmd);
+      break;
+    }
     default:
       // Unexpected.
       error(_tok, "expected linker script command");
@@ -2095,5 +2116,30 @@
   return new (_alloc) Memory(*this, blocks);
 }
 
+Extern *Parser::parseExtern() {
+  assert(_tok._kind == Token::kw_extern && "Expected EXTERN!");
+  consumeToken();
+  if (!expectAndConsume(Token::l_paren, "expected ("))
+    return nullptr;
+
+  // Parse one or more symbols.
+  SmallVector<StringRef, 8> symbols;
+  if (_tok._kind != Token::identifier) {
+    error(_tok, "expected one or more symbols in EXTERN.");
+    return nullptr;
+  }
+  symbols.push_back(_tok._range);
+  consumeToken();
+  while (_tok._kind == Token::identifier) {
+    symbols.push_back(_tok._range);
+    consumeToken();
+  }
+
+  if (!expectAndConsume(Token::r_paren, "expected symbol in EXTERN."))
+    return nullptr;
+
+  return new (_alloc) Extern(*this, symbols);
+}
+
 } // end namespace script
 } // end namespace lld
Index: test/LinkerScript/extern-bad-symbol.test
===================================================================
--- /dev/null
+++ test/LinkerScript/extern-bad-symbol.test
@@ -0,0 +1,22 @@
+/*
+  RUN: linker-script-test %s 2> %t | FileCheck %s
+  RUN: FileCheck -input-file %t -check-prefix=CHECK-ERR %s
+*/
+
+
+EXTERN(a b 3)
+/*
+CHECK-ERR: [[@LINE-2]]:12: error: expected symbol in EXTERN.
+CHECK-ERR-NEXT: {{^EXTERN\(a b 3\)}}
+CHECK-ERR-NEXT: {{^          \^}}
+*/
+
+/*
+CHECK: kw_extern: EXTERN
+CHECK: l_paren: (
+CHECK: identifier: a
+CHECK: identifier: b
+CHECK: number: 3
+CHECK: r_paren: )
+CHECK: eof:
+*/
Index: test/LinkerScript/extern-empty.test
===================================================================
--- /dev/null
+++ test/LinkerScript/extern-empty.test
@@ -0,0 +1,19 @@
+/*
+  RUN: linker-script-test %s 2> %t | FileCheck %s
+  RUN: FileCheck -input-file %t -check-prefix=CHECK-ERR %s
+*/
+
+
+EXTERN()
+/*
+CHECK-ERR: [[@LINE-2]]:8: error: expected one or more symbols in EXTERN.
+CHECK-ERR-NEXT: {{^EXTERN()}}
+CHECK-ERR-NEXT: {{^     \^}}
+*/
+
+/*
+CHECK: kw_extern: EXTERN
+CHECK: l_paren: (
+CHECK: r_paren: )
+CHECK: eof:
+*/
Index: test/LinkerScript/extern-valid.test
===================================================================
--- /dev/null
+++ test/LinkerScript/extern-valid.test
@@ -0,0 +1,29 @@
+/*
+  RUN: linker-script-test %s | FileCheck %s
+*/
+
+EXTERN(a)
+EXTERN(a b)
+EXTERN(_foo _bar _baz)
+
+/*
+CHECK: kw_extern: EXTERN
+CHECK: l_paren: (
+CHECK: identifier: a
+CHECK: r_paren: )
+CHECK: kw_extern: EXTERN
+CHECK: l_paren: (
+CHECK: identifier: a
+CHECK: identifier: b
+CHECK: r_paren: )
+CHECK: kw_extern: EXTERN
+CHECK: l_paren: (
+CHECK: identifier: _foo
+CHECK: identifier: _bar
+CHECK: identifier: _baz
+CHECK: r_paren: )
+CHECK: eof:
+CHECK: EXTERN(a)
+CHECK: EXTERN(a b)
+CHECK: EXTERN(_foo _bar _baz)
+*/