diff --git a/lld/test/ELF/invalid/data-encoding.test b/lld/test/ELF/invalid/data-encoding.test
--- a/lld/test/ELF/invalid/data-encoding.test
+++ b/lld/test/ELF/invalid/data-encoding.test
@@ -4,7 +4,7 @@
 # Check we report this.
 
 # RUN: yaml2obj %s -o %t.o
-# RUN: llvm-ar rcs %t.a %t.o
+# RUN: llvm-ar rcS %t.a %t.o
 
 # RUN: not ld.lld --whole-archive %t.a -o /dev/null 2>&1 | FileCheck %s
 # CHECK: {{.*}}.a({{.*}}.o): corrupted ELF file: invalid data encoding
diff --git a/lld/test/ELF/invalid/invalid-file-class.test b/lld/test/ELF/invalid/invalid-file-class.test
--- a/lld/test/ELF/invalid/invalid-file-class.test
+++ b/lld/test/ELF/invalid/invalid-file-class.test
@@ -11,7 +11,7 @@
 ## EV_CURRENT(1), ELFOSABI_LINUX(3), <padding zero bytes>, ET_REL(1), EM_NONE(0)
 # RUN: echo -e -n "\x7f\x45\x4c\x46\x00\x01\x01\x03\x00\x00\x00\x00\x00\x00\x00\x00\x01\x00" > %t/invalid.o
 
-# RUN: llvm-ar --format=gnu cr %t/invalid-class.a %t/invalid.o
+# RUN: llvm-ar --format=gnu crS %t/invalid-class.a %t/invalid.o
 # RUN: not ld.lld -whole-archive %t/invalid-class.a -o /dev/null 2>&1 | FileCheck %s
 # CHECK: invalid-class.a(invalid.o): corrupted ELF file: invalid file class
 
diff --git a/llvm/include/llvm/Object/SymbolicFile.h b/llvm/include/llvm/Object/SymbolicFile.h
--- a/llvm/include/llvm/Object/SymbolicFile.h
+++ b/llvm/include/llvm/Object/SymbolicFile.h
@@ -173,6 +173,8 @@
   static bool classof(const Binary *v) {
     return v->isSymbolic();
   }
+
+  static bool isSymbolicFile(file_magic Type, const LLVMContext *Context);
 };
 
 inline BasicSymbolRef::BasicSymbolRef(DataRefImpl SymbolP,
diff --git a/llvm/lib/Object/ArchiveWriter.cpp b/llvm/lib/Object/ArchiveWriter.cpp
--- a/llvm/lib/Object/ArchiveWriter.cpp
+++ b/llvm/lib/Object/ArchiveWriter.cpp
@@ -359,22 +359,21 @@
   // reference to it, thus SymbolicFile should be destroyed first.
   LLVMContext Context;
   std::unique_ptr<object::SymbolicFile> Obj;
-  if (identify_magic(Buf.getBuffer()) == file_magic::bitcode) {
+
+  const file_magic Type = identify_magic(Buf.getBuffer());
+  // Treat unsupported file types as having no symbols.
+  if (!object::SymbolicFile::isSymbolicFile(Type, &Context))
+    return Ret;
+  if (Type == file_magic::bitcode) {
     auto ObjOrErr = object::SymbolicFile::createSymbolicFile(
         Buf, file_magic::bitcode, &Context);
-    if (!ObjOrErr) {
-      // FIXME: check only for "not an object file" errors.
-      consumeError(ObjOrErr.takeError());
-      return Ret;
-    }
+    if (!ObjOrErr)
+      return ObjOrErr.takeError();
     Obj = std::move(*ObjOrErr);
   } else {
     auto ObjOrErr = object::SymbolicFile::createSymbolicFile(Buf);
-    if (!ObjOrErr) {
-      // FIXME: check only for "not an object file" errors.
-      consumeError(ObjOrErr.takeError());
-      return Ret;
-    }
+    if (!ObjOrErr)
+      return ObjOrErr.takeError();
     Obj = std::move(*ObjOrErr);
   }
 
@@ -393,7 +392,7 @@
 static Expected<std::vector<MemberData>>
 computeMemberData(raw_ostream &StringTable, raw_ostream &SymNames,
                   object::Archive::Kind Kind, bool Thin, bool Deterministic,
-                  ArrayRef<NewArchiveMember> NewMembers) {
+                  bool NeedSymbols, ArrayRef<NewArchiveMember> NewMembers) {
   static char PaddingData[8] = {'\n', '\n', '\n', '\n', '\n', '\n', '\n', '\n'};
 
   // This ignores the symbol table, but we only need the value mod 8 and the
@@ -494,13 +493,17 @@
                       ModTime, Size);
     Out.flush();
 
-    Expected<std::vector<unsigned>> Symbols =
-        getSymbols(Buf, SymNames, HasObject);
-    if (auto E = Symbols.takeError())
-      return std::move(E);
+    std::vector<unsigned> Symbols;
+    if (NeedSymbols) {
+      Expected<std::vector<unsigned>> SymbolsOrErr =
+          getSymbols(Buf, SymNames, HasObject);
+      if (auto E = SymbolsOrErr.takeError())
+        return std::move(E);
+      Symbols = std::move(*SymbolsOrErr);
+    }
 
     Pos += Header.size() + Data.size() + Padding.size();
-    Ret.push_back({std::move(*Symbols), std::move(Header), Data, Padding});
+    Ret.push_back({std::move(Symbols), std::move(Header), Data, Padding});
   }
   // If there are no symbols, emit an empty symbol table, to satisfy Solaris
   // tools, older versions of which expect a symbol table in a non-empty
@@ -564,8 +567,9 @@
   SmallString<0> StringTableBuf;
   raw_svector_ostream StringTable(StringTableBuf);
 
-  Expected<std::vector<MemberData>> DataOrErr = computeMemberData(
-      StringTable, SymNames, Kind, Thin, Deterministic, NewMembers);
+  Expected<std::vector<MemberData>> DataOrErr =
+      computeMemberData(StringTable, SymNames, Kind, Thin, Deterministic,
+                        WriteSymtab, NewMembers);
   if (Error E = DataOrErr.takeError())
     return E;
   std::vector<MemberData> &Data = *DataOrErr;
diff --git a/llvm/lib/Object/SymbolicFile.cpp b/llvm/lib/Object/SymbolicFile.cpp
--- a/llvm/lib/Object/SymbolicFile.cpp
+++ b/llvm/lib/Object/SymbolicFile.cpp
@@ -41,20 +41,14 @@
   if (Type == file_magic::unknown)
     Type = identify_magic(Data);
 
+  if (!isSymbolicFile(Type, Context))
+    return errorCodeToError(object_error::invalid_file_type);
+
   switch (Type) {
   case file_magic::bitcode:
-    if (Context)
-      return IRObjectFile::create(Object, *Context);
-    LLVM_FALLTHROUGH;
-  case file_magic::unknown:
-  case file_magic::archive:
-  case file_magic::coff_cl_gl_object:
-  case file_magic::macho_universal_binary:
-  case file_magic::windows_resource:
-  case file_magic::pdb:
-  case file_magic::minidump:
-  case file_magic::tapi_file:
-    return errorCodeToError(object_error::invalid_file_type);
+    // Context is guaranteed to be non-null here, because bitcode magic only
+    // indicates a symbolic file when Context is non-null.
+    return IRObjectFile::create(Object, *Context);
   case file_magic::elf:
   case file_magic::elf_executable:
   case file_magic::elf_shared_object:
@@ -95,6 +89,39 @@
         MemoryBufferRef(BCData->getBuffer(), Object.getBufferIdentifier()),
         *Context);
   }
+  default:
+    llvm_unreachable("Unexpected Binary File Type");
+  }
+}
+
+bool SymbolicFile::isSymbolicFile(file_magic Type, const LLVMContext *Context) {
+  switch (Type) {
+  case file_magic::bitcode:
+    return Context != nullptr;
+  case file_magic::elf:
+  case file_magic::elf_executable:
+  case file_magic::elf_shared_object:
+  case file_magic::elf_core:
+  case file_magic::macho_executable:
+  case file_magic::macho_fixed_virtual_memory_shared_lib:
+  case file_magic::macho_core:
+  case file_magic::macho_preload_executable:
+  case file_magic::macho_dynamically_linked_shared_lib:
+  case file_magic::macho_dynamic_linker:
+  case file_magic::macho_bundle:
+  case file_magic::macho_dynamically_linked_shared_lib_stub:
+  case file_magic::macho_dsym_companion:
+  case file_magic::macho_kext_bundle:
+  case file_magic::pecoff_executable:
+  case file_magic::xcoff_object_32:
+  case file_magic::xcoff_object_64:
+  case file_magic::wasm_object:
+  case file_magic::coff_import_library:
+  case file_magic::elf_relocatable:
+  case file_magic::macho_object:
+  case file_magic::coff_object:
+    return true;
+  default:
+    return false;
   }
-  llvm_unreachable("Unexpected Binary File Type");
 }
diff --git a/llvm/test/Object/archive-malformed-object.test b/llvm/test/Object/archive-malformed-object.test
new file mode 100644
--- /dev/null
+++ b/llvm/test/Object/archive-malformed-object.test
@@ -0,0 +1,38 @@
+## Show that the archive library emits error messages when adding malformed
+## objects.
+
+# RUN: rm -rf %t.dir
+# RUN: split-file %s %t.dir
+# RUN: cd %t.dir
+
+## Malformed bitcode object.
+# RUN: llvm-as input.ll -o input.bc
+# RUN: %python -c "with open('input.bc', 'a') as f: f.truncate(10)"
+# RUN: not llvm-ar rc bad.a input.bc 2>&1 | FileCheck %s --check-prefix=ERR1
+
+# ERR1: error: bad.a: Invalid bitcode signature
+
+## Non-bitcode malformed file.
+# RUN: yaml2obj input.yaml -o input.o
+# RUN: not llvm-ar rc bad.a input.o 2>&1 | FileCheck %s --check-prefix=ERR2
+
+# ERR2: error: bad.a: section header table goes past the end of the file: e_shoff = 0x9999
+
+## Don't emit an error if the symbol table is not required.
+# RUN: llvm-ar rcS good.a input.o input.bc
+# RUN: llvm-ar t good.a | FileCheck %s --check-prefix=CONTENTS
+
+# CONTENTS:      input.o
+# CONTENTS-NEXT: input.bc
+
+#--- input.ll
+target datalayout = "e-m:w-i64:64-f80:128-n8:16:32:64-S128"
+target triple = "x86_64-pc-linux"
+
+#--- input.yaml
+--- !ELF
+FileHeader:
+  Class:   ELFCLASS64
+  Data:    ELFDATA2LSB
+  Type:    ET_REL
+  EShOff:  0x9999
diff --git a/llvm/test/Object/archive-unknown-filetype.test b/llvm/test/Object/archive-unknown-filetype.test
new file mode 100644
--- /dev/null
+++ b/llvm/test/Object/archive-unknown-filetype.test
@@ -0,0 +1,11 @@
+## Show that the archive library does not emit an error or add any symbols to
+## the archive symbol table, when it encounters an unknown file type, but still
+## adds the file to the archive.
+
+# RUN: echo something > %t
+# RUN: rm -f %t.a
+# RUN: llvm-ar rc %t.a %t
+# RUN: llvm-ar t %t.a | FileCheck %s --check-prefix=CONTENTS -DFILE=%basename_t
+# RUN: llvm-nm --print-armap %t.a | FileCheck %s --allow-empty --implicit-check-not={{.}}
+
+# CONTENTS: [[FILE]]