Index: ELF/LinkerScript.cpp
===================================================================
--- ELF/LinkerScript.cpp
+++ ELF/LinkerScript.cpp
@@ -1249,6 +1249,9 @@
   // Error checking only for now.
   expect("(");
   skip();
+  // Handle cases like i386:x86-64.
+  if (consume(":"))
+    skip();
   expect(")");
 }
 
Index: test/ELF/linkerscript/outputarch.s
===================================================================
--- test/ELF/linkerscript/outputarch.s
+++ test/ELF/linkerscript/outputarch.s
@@ -8,3 +8,8 @@
 # RUN: llvm-mc -filetype=obj -triple=x86_64-unknown-freebsd %s -o %t1
 # RUN: not ld.lld -shared -o %t2 %t1 %t.script
 # RUN: llvm-readobj %t2 > /dev/null
+
+# RUN: echo "OUTPUT_ARCH(i386:x86-64)" > %t.script
+# RUN: llvm-mc -filetype=obj -triple=x86_64-unknown-freebsd %s -o %t1
+# RUN: ld.lld -o %t2 %t1 %t.script
+# RUN: llvm-readobj %t2 > /dev/null