Index: llvm/utils/gn/secondary/BUILD.gn
===================================================================
--- llvm/utils/gn/secondary/BUILD.gn
+++ llvm/utils/gn/secondary/BUILD.gn
@@ -1,5 +1,6 @@
 group("default") {
   deps = [
+    "//llvm/utils/TableGen:llvm-tblgen",
     "//llvm/tools/llvm-undname",
   ]
 }
Index: llvm/utils/gn/secondary/llvm/lib/DebugInfo/CodeView/BUILD.gn
===================================================================
--- /dev/null
+++ llvm/utils/gn/secondary/llvm/lib/DebugInfo/CodeView/BUILD.gn
@@ -0,0 +1,48 @@
+static_library("CodeView") {
+  output_name = "LLVMDebugInfoCodeView"
+  deps = [
+    "//llvm/lib/DebugInfo/MSF",
+    "//llvm/lib/Support",
+  ]
+  sources = [
+    "AppendingTypeTableBuilder.cpp",
+    "CVSymbolVisitor.cpp",
+    "CVTypeVisitor.cpp",
+    "CodeViewError.cpp",
+    "CodeViewRecordIO.cpp",
+    "ContinuationRecordBuilder.cpp",
+    "DebugChecksumsSubsection.cpp",
+    "DebugCrossExSubsection.cpp",
+    "DebugCrossImpSubsection.cpp",
+    "DebugFrameDataSubsection.cpp",
+    "DebugInlineeLinesSubsection.cpp",
+    "DebugLinesSubsection.cpp",
+    "DebugStringTableSubsection.cpp",
+    "DebugSubsection.cpp",
+    "DebugSubsectionRecord.cpp",
+    "DebugSubsectionVisitor.cpp",
+    "DebugSymbolRVASubsection.cpp",
+    "DebugSymbolsSubsection.cpp",
+    "EnumTables.cpp",
+    "Formatters.cpp",
+    "GlobalTypeTableBuilder.cpp",
+    "LazyRandomTypeCollection.cpp",
+    "Line.cpp",
+    "MergingTypeTableBuilder.cpp",
+    "RecordName.cpp",
+    "RecordSerialization.cpp",
+    "SimpleTypeSerializer.cpp",
+    "StringsAndChecksums.cpp",
+    "SymbolDumper.cpp",
+    "SymbolRecordMapping.cpp",
+    "SymbolSerializer.cpp",
+    "TypeDumpVisitor.cpp",
+    "TypeHashing.cpp",
+    "TypeIndex.cpp",
+    "TypeIndexDiscovery.cpp",
+    "TypeRecordHelpers.cpp",
+    "TypeRecordMapping.cpp",
+    "TypeStreamMerger.cpp",
+    "TypeTableCollection.cpp",
+  ]
+}
Index: llvm/utils/gn/secondary/llvm/lib/DebugInfo/MSF/BUILD.gn
===================================================================
--- /dev/null
+++ llvm/utils/gn/secondary/llvm/lib/DebugInfo/MSF/BUILD.gn
@@ -0,0 +1,12 @@
+static_library("MSF") {
+  output_name = "LLVMDebugInfoMSF"
+  deps = [
+    "//llvm/lib/Support",
+  ]
+  sources = [
+    "MSFBuilder.cpp",
+    "MSFCommon.cpp",
+    "MSFError.cpp",
+    "MappedBlockStream.cpp",
+  ]
+}
Index: llvm/utils/gn/secondary/llvm/lib/MC/BUILD.gn
===================================================================
--- /dev/null
+++ llvm/utils/gn/secondary/llvm/lib/MC/BUILD.gn
@@ -0,0 +1,69 @@
+static_library("MC") {
+  output_name = "LLVMMC"
+  deps = [
+    "//llvm/include/llvm/Config:config",
+    "//llvm/lib/DebugInfo/CodeView",
+    "//llvm/lib/Support",
+  ]
+  public_deps = [
+    # Must be a public_dep because MC's headers include llvm-config.h.
+    "//llvm/include/llvm/Config:llvm-config",
+  ]
+  sources = [
+    "ConstantPools.cpp",
+    "ELFObjectWriter.cpp",
+    "MCAsmBackend.cpp",
+    "MCAsmInfo.cpp",
+    "MCAsmInfoCOFF.cpp",
+    "MCAsmInfoDarwin.cpp",
+    "MCAsmInfoELF.cpp",
+    "MCAsmInfoWasm.cpp",
+    "MCAsmMacro.cpp",
+    "MCAsmStreamer.cpp",
+    "MCAssembler.cpp",
+    "MCCodeEmitter.cpp",
+    "MCCodePadder.cpp",
+    "MCCodeView.cpp",
+    "MCContext.cpp",
+    "MCDwarf.cpp",
+    "MCELFObjectTargetWriter.cpp",
+    "MCELFStreamer.cpp",
+    "MCExpr.cpp",
+    "MCFragment.cpp",
+    "MCInst.cpp",
+    "MCInstPrinter.cpp",
+    "MCInstrAnalysis.cpp",
+    "MCInstrDesc.cpp",
+    "MCLabel.cpp",
+    "MCLinkerOptimizationHint.cpp",
+    "MCMachOStreamer.cpp",
+    "MCMachObjectTargetWriter.cpp",
+    "MCNullStreamer.cpp",
+    "MCObjectFileInfo.cpp",
+    "MCObjectStreamer.cpp",
+    "MCObjectWriter.cpp",
+    "MCRegisterInfo.cpp",
+    "MCSchedule.cpp",
+    "MCSection.cpp",
+    "MCSectionCOFF.cpp",
+    "MCSectionELF.cpp",
+    "MCSectionMachO.cpp",
+    "MCSectionWasm.cpp",
+    "MCStreamer.cpp",
+    "MCSubtargetInfo.cpp",
+    "MCSymbol.cpp",
+    "MCSymbolELF.cpp",
+    "MCTargetOptions.cpp",
+    "MCValue.cpp",
+    "MCWasmObjectTargetWriter.cpp",
+    "MCWasmStreamer.cpp",
+    "MCWin64EH.cpp",
+    "MCWinCOFFStreamer.cpp",
+    "MCWinEH.cpp",
+    "MachObjectWriter.cpp",
+    "StringTableBuilder.cpp",
+    "SubtargetFeature.cpp",
+    "WasmObjectWriter.cpp",
+    "WinCOFFObjectWriter.cpp",
+  ]
+}
Index: llvm/utils/gn/secondary/llvm/lib/TableGen/BUILD.gn
===================================================================
--- /dev/null
+++ llvm/utils/gn/secondary/llvm/lib/TableGen/BUILD.gn
@@ -0,0 +1,17 @@
+static_library("TableGen") {
+  output_name = "LLVMTableGen"
+  deps = [
+    "//llvm/lib/Support",
+  ]
+  sources = [
+    "Error.cpp",
+    "JSONBackend.cpp",
+    "Main.cpp",
+    "Record.cpp",
+    "SetTheory.cpp",
+    "StringMatcher.cpp",
+    "TGLexer.cpp",
+    "TGParser.cpp",
+    "TableGenBackend.cpp",
+  ]
+}
Index: llvm/utils/gn/secondary/llvm/utils/TableGen/BUILD.gn
===================================================================
--- /dev/null
+++ llvm/utils/gn/secondary/llvm/utils/TableGen/BUILD.gn
@@ -0,0 +1,57 @@
+executable("llvm-tblgen") {
+  deps = [
+    "//llvm/include/llvm/Config:llvm-config",
+    "//llvm/lib/MC",
+    "//llvm/lib/Support",
+    "//llvm/lib/TableGen",
+  ]
+  sources = [
+    "AsmMatcherEmitter.cpp",
+    "AsmWriterEmitter.cpp",
+    "AsmWriterInst.cpp",
+    "Attributes.cpp",
+    "CTagsEmitter.cpp",
+    "CallingConvEmitter.cpp",
+    "CodeEmitterGen.cpp",
+    "CodeGenDAGPatterns.cpp",
+    "CodeGenHwModes.cpp",
+    "CodeGenInstruction.cpp",
+    "CodeGenMapTable.cpp",
+    "CodeGenRegisters.cpp",
+    "CodeGenSchedule.cpp",
+    "CodeGenTarget.cpp",
+    "DAGISelEmitter.cpp",
+    "DAGISelMatcher.cpp",
+    "DAGISelMatcherEmitter.cpp",
+    "DAGISelMatcherGen.cpp",
+    "DAGISelMatcherOpt.cpp",
+    "DFAPacketizerEmitter.cpp",
+    "DisassemblerEmitter.cpp",
+    "ExegesisEmitter.cpp",
+    "FastISelEmitter.cpp",
+    "FixedLenDecoderEmitter.cpp",
+    "GlobalISelEmitter.cpp",
+    "InfoByHwMode.cpp",
+    "InstrDocsEmitter.cpp",
+    "InstrInfoEmitter.cpp",
+    "IntrinsicEmitter.cpp",
+    "OptParserEmitter.cpp",
+    "PredicateExpander.cpp",
+    "PseudoLoweringEmitter.cpp",
+    "RISCVCompressInstEmitter.cpp",
+    "RegisterBankEmitter.cpp",
+    "RegisterInfoEmitter.cpp",
+    "SDNodeProperties.cpp",
+    "SearchableTableEmitter.cpp",
+    "SubtargetEmitter.cpp",
+    "SubtargetFeatureInfo.cpp",
+    "TableGen.cpp",
+    "Types.cpp",
+    "WebAssemblyDisassemblerEmitter.cpp",
+    "X86DisassemblerTables.cpp",
+    "X86EVEX2VEXTablesEmitter.cpp",
+    "X86FoldTablesEmitter.cpp",
+    "X86ModRMFilters.cpp",
+    "X86RecognizableInstr.cpp",
+  ]
+}