Index: llvm/include/llvm/ObjectYAML/ELFYAML.h
===================================================================
--- llvm/include/llvm/ObjectYAML/ELFYAML.h
+++ llvm/include/llvm/ObjectYAML/ELFYAML.h
@@ -65,6 +65,7 @@
 LLVM_YAML_STRONG_TYPEDEF(uint32_t, MIPS_ISA)
 
 LLVM_YAML_STRONG_TYPEDEF(StringRef, YAMLFlowString)
+LLVM_YAML_STRONG_TYPEDEF(int64_t, YAMLInt)
 
 // For now, hardcode 64 bits everywhere that 32 or 64 would be needed
 // since 64-bit can hold 32-bit values too.
@@ -439,7 +440,7 @@
 
 struct Relocation {
   llvm::yaml::Hex64 Offset;
-  int64_t Addend;
+  YAMLInt Addend;
   ELF_REL Type;
   Optional<StringRef> Symbol;
 };
@@ -542,6 +543,12 @@
 namespace llvm {
 namespace yaml {
 
+template <> struct ScalarTraits<ELFYAML::YAMLInt> {
+  static void output(const ELFYAML::YAMLInt &Val, void *Ctx, raw_ostream &Out);
+  static StringRef input(StringRef Scalar, void *Ctx, ELFYAML::YAMLInt &Val);
+  static QuotingType mustQuote(StringRef) { return QuotingType::None; }
+};
+
 template <>
 struct ScalarEnumerationTraits<ELFYAML::ELF_ET> {
   static void enumeration(IO &IO, ELFYAML::ELF_ET &Value);
Index: llvm/lib/ObjectYAML/ELFYAML.cpp
===================================================================
--- llvm/lib/ObjectYAML/ELFYAML.cpp
+++ llvm/lib/ObjectYAML/ELFYAML.cpp
@@ -982,6 +982,53 @@
 
 } // end anonymous namespace
 
+void ScalarTraits<ELFYAML::YAMLInt>::output(const ELFYAML::YAMLInt &Val,
+                                            void *Ctx, raw_ostream &Out) {
+  Out << Val;
+}
+
+StringRef ScalarTraits<ELFYAML::YAMLInt>::input(StringRef Scalar, void *Ctx,
+                                                ELFYAML::YAMLInt &Val) {
+  const bool Is64 = static_cast<ELFYAML::Object *>(Ctx)->Header.Class ==
+                    ELFYAML::ELF_ELFCLASS(ELF::ELFCLASS64);
+  StringRef ErrMsg = "invalid number";
+
+  if (Scalar.startswith("-")) {
+    // Do not allow "-0xFE". It looks strange.
+    if (Scalar.drop_front().startswith("0x"))
+      return ErrMsg;
+
+    long long Int;
+    if (getAsSignedInteger(Scalar, /*Radix=*/0, Int))
+      return ErrMsg;
+
+    // For a 32-bit target we allow decimals in a range of a
+    // signed 32-bit integer.
+    if (!Is64 && (Int > INT32_MAX || Int < INT32_MIN))
+      return ErrMsg;
+
+    Val = Int;
+    return StringRef();
+  }
+
+  unsigned long long UInt;
+  if (getAsUnsignedInteger(Scalar, /*Radix=*/0, UInt))
+    return ErrMsg;
+
+  // For a 32-bit target the value shouldn't be greater than UINT32_MAX.
+  if (!Is64 && (UInt > UINT32_MAX))
+    return ErrMsg;
+
+  // Any hex value in a 32/64 bit unsigned integer range is accepted.
+  // A decimal can't be larger than a value of a signed 32/64 bits integer.
+  if (!Scalar.startswith("0x"))
+    if ((Is64 && (UInt > INT64_MAX)) || (!Is64 && (UInt > INT32_MAX)))
+      return ErrMsg;
+
+  Val = UInt;
+  return {};
+}
+
 void MappingTraits<ELFYAML::Symbol>::mapping(IO &IO, ELFYAML::Symbol &Symbol) {
   IO.mapOptional("Name", Symbol.Name, StringRef());
   IO.mapOptional("StName", Symbol.StName);
@@ -1582,7 +1629,7 @@
   } else
     IO.mapRequired("Type", Rel.Type);
 
-  IO.mapOptional("Addend", Rel.Addend, (int64_t)0);
+  IO.mapOptional("Addend", Rel.Addend, (ELFYAML::YAMLInt)0);
 }
 
 void MappingTraits<ELFYAML::Object>::mapping(IO &IO, ELFYAML::Object &Object) {
Index: llvm/test/tools/yaml2obj/ELF/relocation-addend.yaml
===================================================================
--- llvm/test/tools/yaml2obj/ELF/relocation-addend.yaml
+++ llvm/test/tools/yaml2obj/ELF/relocation-addend.yaml
@@ -14,24 +14,23 @@
 
 ## Case 1.2: Check we report an error when an addend is greater than INT64_MAX and
 ## it is in a decimal form. We use (INT64_MAX + 1).
-# RUN: not yaml2obj %s -o %t3 -D ADDEND=9223372036854775808 2>&1 | FileCheck %s --check-prefix=OVERFLOW64
+# RUN: not yaml2obj %s -o %t3 -D ADDEND=9223372036854775808 2>&1 | FileCheck %s --check-prefix=INVALID
 
-# OVERFLOW64: error: invalid number
+# INVALID: error: invalid number
 
 ## Case 1.3: Document we accept an addend with the
 ## value = INT64_MIN = -2^63 = 0x8000000000000000 = -9223372036854775808.
 
 # RUN: yaml2obj %s -o %t3 -D ADDEND=-9223372036854775808
 # RUN: llvm-readobj -r %t3 | FileCheck %s --check-prefix=MIN64
+# RUN: yaml2obj %s -o %t4 -D ADDEND=0x8000000000000000
+# RUN: llvm-readobj -r %t4 | FileCheck %s --check-prefix=MIN64
 
 ## MIN64: 0x0 R_X86_64_PC32 foo 0x8000000000000000
 
-## FIXME: We should support the following case instead.
-# RUN: not yaml2obj %s -o /dev/null -D ADDEND=0x8000000000000000 2>&1 | FileCheck %s --check-prefix=OVERFLOW64
-
 ## Case 1.4: Check we report an error when an addend is less than INT64_MIN and
 ## it is in a decimal form. We use (INT64_MIN - 1).
-# RUN: not yaml2obj %s -o /dev/null -D ADDEND=-9223372036854775809 2>&1 | FileCheck %s --check-prefix=OVERFLOW64
+# RUN: not yaml2obj %s -o /dev/null -D ADDEND=-9223372036854775809 2>&1 | FileCheck %s --check-prefix=INVALID
 
 --- !ELF
 FileHeader:
@@ -69,11 +68,7 @@
 ## Case 2.2: Check we report an error when an addend is greater than INT32_MAX and
 ## it is specified in a decimal form. We use (INT32_MAX + 1).
 
-## FIXME: The following case should fail, see OVERFLOW64.
-# RUN: yaml2obj --docnum=2 %s -o %t6 -D ADDEND=2147483648
-# RUN: llvm-readobj -r %t6 | FileCheck %s --check-prefix=OVERFLOW32-1
-
-# OVERFLOW32-1: 0x0 R_386_PC32 foo 0x80000000{{$}}
+# RUN: not yaml2obj --docnum=2 %s -o /dev/null -D ADDEND=2147483648 2>&1 | FileCheck %s --check-prefix=INVALID
 
 ## Case 2.3: Document we accept an addend with the
 ## value = INT32_MIN = -2^31 = 0x80000000 = -2,147,483,648.
@@ -89,11 +84,13 @@
 ## Case 2.4: Check we report an error when an addend is less than INT32_MIN and
 ## it is in a decimal form. We use (INT32_MIN - 1).
 
-## FIXME: The following case should fail, see OVERFLOW64.
-# RUN: yaml2obj --docnum=2 %s -o %t9 -D ADDEND=-2147483649
-# RUN: llvm-readobj -r %t9 | FileCheck %s --check-prefix=OVERFLOW32-2
+# RUN: not yaml2obj --docnum=2 %s -o /dev/null -D ADDEND=-2147483649 2>&1 | FileCheck %s --check-prefix=INVALID
 
-# OVERFLOW32-2: 0x0 R_386_PC32 foo 0x7FFFFFFF{{$}}
+## Case 2.5: ELFCLASS32 objects use 32 bits fields to store an addend.
+## Hence it does not make sence to allow addend greater than UINT32_MAX.
+## Check we report an error in this case.
+# RUN: not yaml2obj --docnum=2 %s -D ADDEND=0x100000000 2>&1 | FileCheck %s --check-prefix=INVALID
+# RUN: not yaml2obj --docnum=2 %s -D ADDEND=4294967296  2>&1 | FileCheck %s --check-prefix=INVALID
 
 --- !ELF
 FileHeader:
@@ -115,3 +112,15 @@
         Addend: [[ADDEND]]
 Symbols:
   - Name: foo
+
+## Case 3: Check we do not allow a minus before the hex value of an addend.
+## I.e. we do not allow "-0xFE".
+# RUN: not yaml2obj --docnum=1 %s -D ADDEND=-0x1 2>&1 | FileCheck %s --check-prefix=INVALID
+# RUN: not yaml2obj --docnum=2 %s -D ADDEND=-0x1 2>&1 | FileCheck %s --check-prefix=INVALID
+
+## Case 4: Check we do not allow invalid values.
+# RUN: not yaml2obj --docnum=1 %s -D ADDEND=0x1122QQEE 2>&1 | FileCheck %s --check-prefix=INVALID
+# RUN: not yaml2obj --docnum=2 %s -D ADDEND=-0x1122QQEE 2>&1 | FileCheck %s --check-prefix=INVALID
+# RUN: not yaml2obj --docnum=1 %s -D ADDEND=1234Q5 2>&1 | FileCheck %s --check-prefix=INVALID
+# RUN: not yaml2obj --docnum=2 %s -D ADDEND=-1234Q5 2>&1 | FileCheck %s --check-prefix=INVALID
+# RUN: not yaml2obj --docnum=2 %s -D ADDEND=foo 2>&1 | FileCheck %s --check-prefix=INVALID