Index: ELF/Target.cpp
===================================================================
--- ELF/Target.cpp
+++ ELF/Target.cpp
@@ -631,7 +631,11 @@
 RelExpr X86_64TargetInfo<ELFT>::getRelExpr(uint32_t Type,
                                            const SymbolBody &S) const {
   switch (Type) {
-  default:
+  case R_X86_64_32:
+  case R_X86_64_32S:
+  case R_X86_64_64:
+  case R_X86_64_DTPOFF32:
+  case R_X86_64_DTPOFF64:
     return R_ABS;
   case R_X86_64_TPOFF32:
     return R_TLS;
@@ -657,6 +661,10 @@
     return R_GOT_PC;
   case R_X86_64_NONE:
     return R_HINT;
+  default:
+    error("do not know how to handle relocation '" + toString(Type) + "' (" +
+          Twine(Type) + ")");
+    return R_HINT;
   }
 }
 
@@ -878,7 +886,7 @@
     write64le(Loc, Val);
     break;
   default:
-    error(getErrorLocation(Loc) + "unrecognized reloc " + Twine(Type));
+    llvm_unreachable("unexpected relocation");
   }
 }
 
Index: test/ELF/invalid/invalid-relocation-x64.s
===================================================================
--- test/ELF/invalid/invalid-relocation-x64.s
+++ test/ELF/invalid/invalid-relocation-x64.s
@@ -26,5 +26,5 @@
         Type:            R_X86_64_NONE
 
 # RUN: not ld.lld %p/Inputs/invalid-relocation-x64.elf -o %t2 2>&1 | FileCheck %s
-# CHECK: unrecognized reloc 152
-# CHECK: unrecognized reloc 153
+# CHECK: do not know how to handle relocation 'Unknown' (152)
+# CHECK: do not know how to handle relocation 'Unknown' (153)