Index: ELF/InputFiles.cpp
===================================================================
--- ELF/InputFiles.cpp
+++ ELF/InputFiles.cpp
@@ -1193,6 +1193,8 @@
   unsigned char Endian;
   std::tie(Size, Endian) = getElfArchType(MB.getBuffer());
 
+  if (!MB.getBuffer().startswith(ElfMagic))
+    fatal(MB.getBufferIdentifier() + ": expected ELF file in archive");
   if (Endian != ELFDATA2LSB && Endian != ELFDATA2MSB)
     fatal(MB.getBufferIdentifier() + ": invalid data encoding");
   if (Size != ELFCLASS32 && Size != ELFCLASS64)
Index: test/ELF/invalid/Inputs/not-elf.a
===================================================================
--- /dev/null
+++ test/ELF/invalid/Inputs/not-elf.a
@@ -0,0 +1,2 @@
+!<arch>
+test.o/         0           0     0     644     0         `
Index: test/ELF/invalid/invalid-elf.test
===================================================================
--- test/ELF/invalid/invalid-elf.test
+++ test/ELF/invalid/invalid-elf.test
@@ -1,6 +1,10 @@
 # REQUIRES: x86
 # RUN: llvm-mc %s -o %t -filetype=obj -triple x86_64-pc-linux
 
+# RUN: not ld.lld %t %p/Inputs/not-elf.a -o %t2 2>&1 | \
+# RUN:   FileCheck --check-prefix=NOT-ELF %s
+# NOT-ELF: test.o: expected ELF file in archive
+
 # RUN: not ld.lld %t %p/Inputs/data-encoding.a -o %t2 2>&1 | \
 # RUN:   FileCheck --check-prefix=INVALID-DATA-ENC %s
 # INVALID-DATA-ENC: test.o: invalid data encoding