Index: include/llvm/BinaryFormat/ELFRelocs/AVR.def
===================================================================
--- include/llvm/BinaryFormat/ELFRelocs/AVR.def
+++ include/llvm/BinaryFormat/ELFRelocs/AVR.def
@@ -38,3 +38,6 @@
 ELF_RELOC(R_AVR_LDS_STS_16,           33)
 ELF_RELOC(R_AVR_PORT6,                34)
 ELF_RELOC(R_AVR_PORT5,                35)
+ELF_RELOC(R_AVR_DIFF8,                36)
+ELF_RELOC(R_AVR_DIFF16,               37)
+ELF_RELOC(R_AVR_DIFF32,               38)
Index: lib/Target/AVR/AsmParser/AVRAsmParser.cpp
===================================================================
--- lib/Target/AVR/AsmParser/AVRAsmParser.cpp
+++ lib/Target/AVR/AsmParser/AVRAsmParser.cpp
@@ -80,6 +80,8 @@
                       uint64_t const &ErrorInfo);
   bool missingFeature(SMLoc const &Loc, uint64_t const &ErrorInfo);
 
+  bool parseLiteralValues(unsigned Size, SMLoc L);
+
 public:
   AVRAsmParser(const MCSubtargetInfo &STI, MCAsmParser &Parser,
                const MCInstrInfo &MII, const MCTargetOptions &Options)
@@ -404,11 +406,14 @@
   size_t ReadCount = Parser.getLexer().peekTokens(tokens);
 
   if (ReadCount == 2) {
-    if (tokens[0].getKind() == AsmToken::Identifier &&
-        tokens[1].getKind() == AsmToken::LParen) {
+    if ((tokens[0].getKind() == AsmToken::Identifier &&
+         tokens[1].getKind() == AsmToken::LParen) ||
+        (tokens[0].getKind() == AsmToken::LParen &&
+         tokens[1].getKind() == AsmToken::Minus)) {
 
       AsmToken::TokenKind CurTok = Parser.getLexer().getKind();
-      if (CurTok == AsmToken::Minus) {
+      if (CurTok == AsmToken::Minus ||
+          tokens[1].getKind() == AsmToken::Minus) {
         isNegated = true;
       } else {
         assert(CurTok == AsmToken::Plus);
@@ -416,7 +421,8 @@
       }
 
       // Eat the sign
-      Parser.Lex();
+      if (CurTok == AsmToken::Minus || CurTok == AsmToken::Plus)
+        Parser.Lex();
     }
   }
 
@@ -432,14 +438,30 @@
   if (ModifierKind != AVRMCExpr::VK_AVR_None) {
     Parser.Lex();
     Parser.Lex(); // Eat modifier name and parenthesis
+    // FIXME: Not support gs(foo) so just eat gs.
+    if (Parser.getTok().getString() == "gs" &&
+        Parser.getTok().getKind() == AsmToken::Identifier) {
+      Parser.Lex();
+    }
   } else {
     return Error(Parser.getTok().getLoc(), "unknown modifier");
   }
 
+  if (tokens[1].getKind() == AsmToken::Minus) {
+    Parser.Lex();
+    assert(Parser.getTok().getKind() == AsmToken::LParen);
+    Parser.Lex(); // Eat the sign and parenthesis
+  }
+
   MCExpr const *InnerExpression;
   if (getParser().parseExpression(InnerExpression))
     return true;
 
+  if (tokens[1].getKind() == AsmToken::Minus) {
+    assert(Parser.getTok().getKind() == AsmToken::RParen);
+    Parser.Lex(); // Eat closing parenthesis
+  }
+
   // If we have a modifier wrap the inner expression
   assert(Parser.getTok().getKind() == AsmToken::RParen);
   Parser.Lex(); // Eat closing parenthesis
@@ -580,7 +602,35 @@
   return false;
 }
 
-bool AVRAsmParser::ParseDirective(llvm::AsmToken DirectiveID) { return true; }
+bool AVRAsmParser::ParseDirective(llvm::AsmToken DirectiveID) {
+  StringRef IDVal = DirectiveID.getIdentifier();
+  if (IDVal == ".long")
+    parseLiteralValues(8, DirectiveID.getLoc());
+  else if (IDVal == ".word")
+    parseLiteralValues(4, DirectiveID.getLoc());
+  else if (IDVal == ".short")
+    parseLiteralValues(2, DirectiveID.getLoc());
+  else if (IDVal == ".byte")
+    parseLiteralValues(1, DirectiveID.getLoc());
+  return true;
+}
+
+bool AVRAsmParser::parseLiteralValues(unsigned Size, SMLoc L) {
+  MCAsmParser &Parser = getParser();
+  if (Parser.getTok().getKind() == AsmToken::Identifier &&
+      Parser.getLexer().peekTok().getKind() == AsmToken::LParen) {
+    const MCExpr *Value;
+    return Parser.parseExpression(Value);
+  }
+  auto parseOne = [&]() -> bool {
+    const MCExpr *Value;
+    if (Parser.parseExpression(Value))
+      return true;
+    Parser.getStreamer().EmitValue(Value, Size, L);
+    return false;
+  };
+  return (parseMany(parseOne));
+}
 
 extern "C" void LLVMInitializeAVRAsmParser() {
   RegisterMCAsmParser<AVRAsmParser> X(getTheAVRTarget());
Index: lib/Target/AVR/MCTargetDesc/AVRAsmBackend.cpp
===================================================================
--- lib/Target/AVR/MCTargetDesc/AVRAsmBackend.cpp
+++ lib/Target/AVR/MCTargetDesc/AVRAsmBackend.cpp
@@ -423,6 +423,9 @@
 
       {"fixup_sym_diff", 0, 32, 0},
       {"fixup_16_ldst", 0, 16, 0},
+      {"fixup_diff8", 0, 8, 0},
+      {"fixup_diff16", 0, 16, 0},
+      {"fixup_diff32", 0, 32, 0},
 
       {"fixup_lds_sts_16", 0, 16, 0},
 
Index: lib/Target/AVR/MCTargetDesc/AVRELFObjectWriter.cpp
===================================================================
--- lib/Target/AVR/MCTargetDesc/AVRELFObjectWriter.cpp
+++ lib/Target/AVR/MCTargetDesc/AVRELFObjectWriter.cpp
@@ -107,6 +107,12 @@
     return ELF::R_AVR_SYM_DIFF;
   case AVR::fixup_16_ldst:
     return ELF::R_AVR_16_LDST;
+  case AVR::fixup_diff8:
+    return ELF::R_AVR_DIFF8;
+  case AVR::fixup_diff16:
+    return ELF::R_AVR_DIFF16;
+  case AVR::fixup_diff32:
+    return ELF::R_AVR_DIFF32;
   case AVR::fixup_lds_sts_16:
     return ELF::R_AVR_LDS_STS_16;
   case AVR::fixup_port6:
Index: lib/Target/AVR/MCTargetDesc/AVRFixupKinds.h
===================================================================
--- lib/Target/AVR/MCTargetDesc/AVRFixupKinds.h
+++ lib/Target/AVR/MCTargetDesc/AVRFixupKinds.h
@@ -119,6 +119,9 @@
   /// Is the only stateful fixup. We do not support it yet.
   fixup_sym_diff,
   fixup_16_ldst,
+  fixup_diff8,
+  fixup_diff16,
+  fixup_diff32,
 
   fixup_lds_sts_16,
 
Index: test/MC/AVR/relocations.s
===================================================================
--- test/MC/AVR/relocations.s
+++ test/MC/AVR/relocations.s
@@ -2,6 +2,10 @@
 
 ; CHECK: RELOCATION RECORDS FOR
 
+; CHECK: RELOCATION RECORDS BAR
+bar:
+  jmp bar
+
 ; CHECK-NEXT: R_AVR_LDI SYMBOL+3
 ldi r21, SYMBOL+3
 
@@ -34,27 +38,32 @@
 
 ; CHECK-NEXT: R_AVR_LO8_LDI_NEG abc
 ldi r16, -lo8(abc)
+ldi r16, lo8(-(abc))
 
 ; CHECK-NEXT: R_AVR_HI8_LDI_NEG abc
 ldi r16, -hi8(abc)
+ldi r16, hi8(-(abc))
 
 ; CHECK-NEXT: R_AVR_HH8_LDI foo
 ldi r16, hh8(foo)
 
 ; CHECK-NEXT: R_AVR_HH8_LDI_NEG foo
 ldi r16, -hh8(foo)
+ldi r16, hh8(-(foo))
 
 ; CHECK-NEXT: R_AVR_HH8_LDI foo
 ldi r24, hlo8(foo)
 
 ; CHECK-NEXT: R_AVR_HH8_LDI_NEG foo
 ldi r24, -hlo8(foo)
+ldi r24, hlo8(-(foo))
 
 ; CHECK-NEXT: R_AVR_MS8_LDI bar
 ldi r24, hhi8(bar)
 
 ; CHECK-NEXT: R_AVR_MS8_LDI_NEG bar
 ldi r24, -hhi8(bar)
+ldi r24, hhi8(-(bar))
 
 ; CHECK-NEXT: R_AVR_LO8_LDI_PM foo
 ldi r17, pm_lo8(foo)
@@ -67,9 +76,42 @@
 
 ; CHECK-NEXT: R_AVR_LO8_LDI_PM_NEG
 ldi r25, -pm_lo8(foo)
+ldi r25, pm_lo8(-(foo))
 
 ; CHECK-NEXT: R_AVR_HI8_LDI_PM_NEG
 ldi r25, -pm_hi8(foo)
+ldi r25, pm_hi8(-(foo))
 
 ; CHECK-NEXT: R_AVR_HH8_LDI_PM_NEG
 ldi r25, -pm_hh8(foo)
+ldi r25, pm_hh8(-(foo))
+
+; CHECK-NEXT: R_AVR_LO8_LDI_GS
+ldi r17, lo8(gs(foo))
+
+; CHECK-NEXT: R_AVR_HI8_LDI_GS
+ldi r18, hi8(gs(foo))
+
+; CHECK-NEXT: R_AVR_16_PM
+.short foo
+
+; CHECK-NEXT: R_AVR_8
+.byte foo
+
+; CHECK-NEXT: R_AVR_8_LO8
+.byte lo8(foo)
+
+; CHECK-NEXT: R_AVR_8_HI8
+.byte hi8(foo)
+
+; CHECK-NEXT: R_AVR_8_HLO8
+.byte hlo8(foo)
+
+; CHECK-NEXT: R_AVR_DIFF8
+.byte foo - bar
+
+; CHECK-NEXT: R_AVR_DIFF16
+.word foo - bar
+
+; CHECK-NEXT: R_AVR_DIFF32
+.long foo - bar