Index: llvm/trunk/lib/MC/MCXCOFFStreamer.cpp
===================================================================
--- llvm/trunk/lib/MC/MCXCOFFStreamer.cpp
+++ llvm/trunk/lib/MC/MCXCOFFStreamer.cpp
@@ -10,11 +10,12 @@
 //
 //===----------------------------------------------------------------------===//
 
-#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"
 #include "llvm/MC/MCSymbolXCOFF.h"
+#include "llvm/MC/MCXCOFFStreamer.h"
 #include "llvm/Support/TargetRegistry.h"
 
 using namespace llvm;
@@ -72,7 +73,8 @@
   return S;
 }
 
-void MCXCOFFStreamer::EmitXCOFFLocalCommonSymbol(MCSymbol *Symbol, uint64_t Size,
-                                            unsigned ByteAlign) {
-  report_fatal_error("Emission of local commons not implemented yet.");
+void MCXCOFFStreamer::EmitXCOFFLocalCommonSymbol(MCSymbol *Symbol,
+                                                 uint64_t Size,
+                                                 unsigned ByteAlignment) {
+  EmitCommonSymbol(Symbol, Size, ByteAlignment);
 }
Index: llvm/trunk/lib/MC/XCOFFObjectWriter.cpp
===================================================================
--- llvm/trunk/lib/MC/XCOFFObjectWriter.cpp
+++ llvm/trunk/lib/MC/XCOFFObjectWriter.cpp
@@ -235,6 +235,13 @@
         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.");
+      BSSCsects.emplace_back(MCSec);
+      WrapperMap[MCSec] = &BSSCsects.back();
+      break;
     default:
       report_fatal_error("Unhandled mapping of csect to section.");
     }
Index: llvm/trunk/test/CodeGen/PowerPC/aix-xcoff-lcomm.ll
===================================================================
--- llvm/trunk/test/CodeGen/PowerPC/aix-xcoff-lcomm.ll
+++ llvm/trunk/test/CodeGen/PowerPC/aix-xcoff-lcomm.ll
@@ -1,6 +1,14 @@
 ; 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
+
+; RUN: not llc -mtriple powerpc64-ibm-aix-xcoff -filetype=obj < %s 2>&1 | \
+; RUN: FileCheck --check-prefix=OBJ64 %s
+; OBJ64: LLVM ERROR: 64-bit XCOFF object files are not supported yet.
+
 @a = internal global i32 0, align 4
 @b = internal global i64 0, align 8
 @c = internal global i16 0, align 2
@@ -8,3 +16,32 @@
 ; CHECK:      .lcomm a,4,a,2
 ; CHECK-NEXT: .lcomm b,8,b,3
 ; CHECK-NEXT: .lcomm c,2,c,1
+
+; 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: ]