diff --git a/llvm/lib/MC/MCXCOFFStreamer.cpp b/llvm/lib/MC/MCXCOFFStreamer.cpp
--- a/llvm/lib/MC/MCXCOFFStreamer.cpp
+++ b/llvm/lib/MC/MCXCOFFStreamer.cpp
@@ -11,6 +11,7 @@
 //===----------------------------------------------------------------------===//
 
 #include "llvm/MC/MCXCOFFStreamer.h"
+#include "llvm/BinaryFormat/XCOFF.h"
 #include "llvm/MC/MCAsmBackend.h"
 #include "llvm/MC/MCCodeEmitter.h"
 #include "llvm/MC/MCObjectWriter.h"
@@ -72,7 +73,8 @@
   return S;
 }
 
-void MCXCOFFStreamer::EmitXCOFFLocalCommonSymbol(MCSymbol *Symbol, uint64_t Size,
-                                            unsigned ByteAlign) {
-  llvm_unreachable("Not implemented yet.");
-}
\ No newline at end of file
+void MCXCOFFStreamer::EmitXCOFFLocalCommonSymbol(MCSymbol *Symbol,
+                                                 uint64_t Size,
+                                                 unsigned ByteAlignment) {
+  EmitCommonSymbol(Symbol, Size, ByteAlignment);
+}
diff --git a/llvm/lib/MC/XCOFFObjectWriter.cpp b/llvm/lib/MC/XCOFFObjectWriter.cpp
--- a/llvm/lib/MC/XCOFFObjectWriter.cpp
+++ b/llvm/lib/MC/XCOFFObjectWriter.cpp
@@ -233,6 +233,12 @@
         break;
       }
       report_fatal_error("Unhandled mapping of read-write csect to section");
+    case XCOFF::XMC_BS:
+      assert(XCOFF::XTY_CM == MCSec->getCSectType() &&
+             "Mapping invalid csect. Csect with bss storage class must be "
+             "common type.");
+      Add(&BSS, BSSCSects, MCSec);
+      break;
     default:
       report_fatal_error("Unhandled mapping of csect to section");
     }
diff --git a/llvm/test/CodeGen/PowerPC/aix-xcoff-lcomm.ll b/llvm/test/CodeGen/PowerPC/aix-xcoff-lcomm.ll
--- a/llvm/test/CodeGen/PowerPC/aix-xcoff-lcomm.ll
+++ b/llvm/test/CodeGen/PowerPC/aix-xcoff-lcomm.ll
@@ -1,6 +1,10 @@
 ; RUN: llc -mtriple powerpc-ibm-aix-xcoff < %s | FileCheck %s
 ; RUN: llc -mtriple powerpc64-ibm-aix-xcoff < %s | FileCheck %s
 
+; RUN: llc -mtriple powerpc-ibm-aix-xcoff -filetype=obj -o %t.o < %s
+; RUN: llvm-readobj --section-headers --file-header %t.o | \
+; RUN: FileCheck --check-prefix=OBJ %s
+
 @a = internal global i32 0, align 4
 @b = internal global i64 0, align 8
 @c = internal global i16 0, align 2
@@ -8,3 +12,33 @@
 ; CHECK:      .lcomm a,4,a,2
 ; CHECK-NEXT: .lcomm b,8,b,3
 ; CHECK-NEXT: .lcomm c,2,c,1
+; XCOFF64: LLVM ERROR: 64-bit XCOFF object files are not supported yet.
+
+; OBJ:      File: {{.*}}aix-xcoff-lcomm.ll.tmp.o
+; OBJ-NEXT: Format: aixcoff-rs6000
+; OBJ-NEXT: Arch: powerpc
+; OBJ-NEXT: AddressSize: 32bit
+; OBJ-NEXT: FileHeader {
+; OBJ-NEXT:   Magic: 0x1DF
+; OBJ-NEXT:   NumberOfSections: 1
+; OBJ-NEXT:   TimeStamp:
+; OBJ-NEXT:   SymbolTableOffset: 0x3C
+; OBJ-NEXT:   SymbolTableEntries: 6
+; OBJ-NEXT:   OptionalHeaderSize: 0x0
+; OBJ-NEXT:   Flags: 0x0
+; OBJ-NEXT: }
+; OBJ-NEXT: Sections [
+; OBJ-NEXT:   Section {
+; OBJ-NEXT:     Index: 1
+; OBJ-NEXT:     Name: .bss
+; OBJ-NEXT:     PhysicalAddress: 0x0
+; OBJ-NEXT:     VirtualAddress: 0x0
+; OBJ-NEXT:     Size: 0x14
+; OBJ-NEXT:     RawDataOffset: 0x0
+; OBJ-NEXT:     RelocationPointer: 0x0
+; OBJ-NEXT:     LineNumberPointer: 0x0
+; OBJ-NEXT:     NumberOfRelocations: 0
+; OBJ-NEXT:     NumberOfLineNumbers: 0
+; OBJ-NEXT:     Type: STYP_BSS (0x80)
+; OBJ-NEXT:   }
+; OBJ-NEXT: ]