diff --git a/llvm/lib/ObjectYAML/DWARFEmitter.cpp b/llvm/lib/ObjectYAML/DWARFEmitter.cpp
--- a/llvm/lib/ObjectYAML/DWARFEmitter.cpp
+++ b/llvm/lib/ObjectYAML/DWARFEmitter.cpp
@@ -461,6 +461,8 @@
       emitFileEntry(OS, File);
     OS.write('\0');
 
+    uint8_t AddrSize = DI.Is64BitAddrSize ? 8 : 4;
+
     for (auto Op : LineTable.Opcodes) {
       writeInteger((uint8_t)Op.Opcode, OS, DI.IsLittleEndian);
       if (Op.Opcode == 0) {
@@ -469,10 +471,9 @@
         switch (Op.SubOpcode) {
         case dwarf::DW_LNE_set_address:
         case dwarf::DW_LNE_set_discriminator:
-          // TODO: Test this error.
-          if (Error Err = writeVariableSizedInteger(
-                  Op.Data, DI.CompileUnits[0].AddrSize, OS, DI.IsLittleEndian))
-            return Err;
+          // FIXME: The operands of set_discriminator is not an address.
+          cantFail(writeVariableSizedInteger(Op.Data, AddrSize, OS,
+                                             DI.IsLittleEndian));
           break;
         case dwarf::DW_LNE_define_file:
           emitFileEntry(OS, Op.FileEntry);
diff --git a/llvm/test/tools/yaml2obj/ELF/DWARF/debug-line.yaml b/llvm/test/tools/yaml2obj/ELF/DWARF/debug-line.yaml
--- a/llvm/test/tools/yaml2obj/ELF/DWARF/debug-line.yaml
+++ b/llvm/test/tools/yaml2obj/ELF/DWARF/debug-line.yaml
@@ -317,3 +317,56 @@
       IncludeDirs:           []
       Files:                 []
       Opcodes:               []
+
+## h) Test that the address size is inferred from the target machine.
+
+# RUN: yaml2obj --docnum=8 -DBITS=64 -DADDR=0x1234567890abcdef %s -o %t8.64-bit.o
+# RUN: llvm-readelf --hex-dump=.debug_line %t8.64-bit.o | \
+# RUN:   FileCheck %s --check-prefix=ADDRSIZE -DADDR="efcdab90 78563412"
+
+#      ADDRSIZE: Hex dump of section '.debug_line':
+# ADDRSIZE-NEXT: 0x00000000 34120000 02003412 00000101 010e0d00 4.....4.........
+##                          ^-------                            unit_length (4-byte)
+##                                   ^---                       version (2-byte)
+##                                       ^--------              header_length (4-byte)
+##                                                ^-            minimum_instruction_length (1-byte)
+##                                                  ^-          default_is_stmt (1-byte)
+##                                                     ^-       line_base (1-byte)
+##                                                       ^-     line_range (1-byte)
+##                                                         ^-   opcode_base (1-byte)
+##                                                           ^- null byte for terminating include_directories
+# ADDRSIZE-NEXT: 0x00000010 00000902 [[ADDR]]
+##                          ^-                                  null byte for terminating file_names
+##                            ^-                                DW_LNS_extended_op
+##                              ^-                              extended op length (ULEB128) 0x09
+##                                ^-                            DW_LNE_set_address
+##                                   ^-------                   address
+
+# RUN: yaml2obj --docnum=8 -DBITS=32 -DADDR=0x12345678 %s -o %t8.32-bit.o
+# RUN: llvm-readelf --hex-dump=.debug_line %t8.32-bit.o | \
+# RUN:   FileCheck %s --check-prefix=ADDRSIZE -DADDR="78563412"
+
+--- !ELF
+FileHeader:
+  Class:   ELFCLASS[[BITS]]
+  Data:    ELFDATA2LSB
+  Type:    ET_EXEC
+  Machine: EM_X86_64
+DWARF:
+  debug_line:
+    - Length:                0x1234
+      Version:               2
+      PrologueLength:        0x1234
+      MinInstLength:         1
+      DefaultIsStmt:         1
+      LineBase:              1
+      LineRange:             14
+      OpcodeBase:            13
+      StandardOpcodeLengths: []
+      IncludeDirs:           []
+      Files:                 []
+      Opcodes:
+        - Opcode:    DW_LNS_extended_op
+          ExtLen:    9
+          SubOpcode: DW_LNE_set_address
+          Data:      [[ADDR]]