diff --git a/lld/ELF/Options.td b/lld/ELF/Options.td
index 7f04e052fd3171..3bb358c457d3cf 100644
--- a/lld/ELF/Options.td
+++ b/lld/ELF/Options.td
@@ -304,8 +304,8 @@ def no_undefined: F<"no-undefined">,
 def o: JoinedOrSeparate<["-"], "o">, MetaVarName<"<path>">,
   HelpText<"Path to file to write output">;
 
-def oformat: Separate<["--"], "oformat">, MetaVarName<"<format>">,
-  HelpText<"Specify the binary format for the output object file">;
+defm oformat: EEq<"oformat", "Specify the binary format for the output object file">,
+  MetaVarName<"[elf,binary]">;
 
 def omagic: FF<"omagic">, MetaVarName<"<magic>">,
   HelpText<"Set the text and data sections to be readable and writable, do not page align sections, link against static libraries">;
diff --git a/lld/test/ELF/oformat-binary.s b/lld/test/ELF/oformat-binary.s
index 4b2ad8ec711fdc..38af6805140fce 100644
--- a/lld/test/ELF/oformat-binary.s
+++ b/lld/test/ELF/oformat-binary.s
@@ -1,7 +1,7 @@
 # REQUIRES: x86
 # RUN: llvm-mc -filetype=obj -triple=x86_64-unknown-linux %s -o %t
 
-# RUN: ld.lld -o %t.out %t --oformat binary
+# RUN: ld.lld -o %t.out %t --oformat=binary
 # RUN: od -t x1 -v %t.out | FileCheck %s
 # CHECK:      0000000 90 11 22
 # CHECK-NEXT: 0000003
@@ -46,7 +46,7 @@
 # ERR: unknown --oformat value: foo
 
 # RUN: ld.lld -o /dev/null %t --oformat elf
-# RUN: ld.lld -o /dev/null %t --oformat elf-foo
+# RUN: ld.lld -o /dev/null %t --oformat=elf-foo
 
 .text
 .align 4