Index: llvm/trunk/utils/gn/build/run_tablegen.py
===================================================================
--- llvm/trunk/utils/gn/build/run_tablegen.py
+++ llvm/trunk/utils/gn/build/run_tablegen.py
@@ -0,0 +1,8 @@
+#!/usr/bin/env python
+"""Runs tablegen."""
+
+import subprocess
+import sys
+
+# Prefix with ./ to run built binary, not arbitrary stuff from PATH.
+sys.exit(subprocess.call(['./' + sys.argv[1]] + sys.argv[2:]))
Index: llvm/trunk/utils/gn/secondary/BUILD.gn
===================================================================
--- llvm/trunk/utils/gn/secondary/BUILD.gn
+++ llvm/trunk/utils/gn/secondary/BUILD.gn
@@ -1,7 +1,8 @@
 group("default") {
   deps = [
-    "//llvm/utils/TableGen:llvm-tblgen",
+    "//llvm/lib/IR",
     "//llvm/tools/llvm-undname",
+    "//llvm/utils/TableGen:llvm-tblgen",
   ]
 }
 
Index: llvm/trunk/utils/gn/secondary/llvm/include/llvm/IR/BUILD.gn
===================================================================
--- llvm/trunk/utils/gn/secondary/llvm/include/llvm/IR/BUILD.gn
+++ llvm/trunk/utils/gn/secondary/llvm/include/llvm/IR/BUILD.gn
@@ -0,0 +1,18 @@
+import("//llvm/utils/TableGen/tablegen.gni")
+
+tablegen("IntrinsicEnums") {
+  visibility = [ "//llvm/lib/IR" ]
+  args = [ "-gen-intrinsic-enums" ]
+  td_file = "Intrinsics.td"
+}
+
+tablegen("IntrinsicImpl") {
+  visibility = [ "//llvm/lib/IR" ]
+  args = [ "-gen-intrinsic-impl" ]
+  td_file = "Intrinsics.td"
+}
+
+tablegen("Attributes") {
+  visibility = [ "//llvm/lib/IR" ]
+  args = [ "-gen-attrs" ]
+}
Index: llvm/trunk/utils/gn/secondary/llvm/lib/BinaryFormat/BUILD.gn
===================================================================
--- llvm/trunk/utils/gn/secondary/llvm/lib/BinaryFormat/BUILD.gn
+++ llvm/trunk/utils/gn/secondary/llvm/lib/BinaryFormat/BUILD.gn
@@ -0,0 +1,13 @@
+static_library("BinaryFormat") {
+  output_name = "LLVMBinaryFormat"
+  deps = [
+    "//llvm/lib/Support",
+  ]
+  sources = [
+    "Dwarf.cpp",
+    "Magic.cpp",
+    "MsgPackReader.cpp",
+    "MsgPackWriter.cpp",
+    "Wasm.cpp",
+  ]
+}
Index: llvm/trunk/utils/gn/secondary/llvm/lib/IR/BUILD.gn
===================================================================
--- llvm/trunk/utils/gn/secondary/llvm/lib/IR/BUILD.gn
+++ llvm/trunk/utils/gn/secondary/llvm/lib/IR/BUILD.gn
@@ -0,0 +1,81 @@
+import("//llvm/utils/TableGen/tablegen.gni")
+
+tablegen("AttributesCompatFunc") {
+  visibility = [ ":IR" ]
+  args = [ "-gen-attrs" ]
+}
+
+static_library("IR") {
+  output_name = "LLVMCore"
+  public_deps = [
+    # Must be public_dep because IR's public headers include llvm-config.h.
+    "//llvm/include/llvm/Config:llvm-config",
+
+    # Must be public_dep because IR's public headers include Attributes.inc.
+    "//llvm/include/llvm/IR:Attributes",
+
+    # Must be public_dep because IR's public headers include IntrinsicEnums.inc.
+    "//llvm/include/llvm/IR:IntrinsicEnums",
+  ]
+  deps = [
+    ":AttributesCompatFunc",
+    "//llvm/include/llvm/IR:IntrinsicImpl",
+    "//llvm/lib/BinaryFormat",
+    "//llvm/lib/Support",
+  ]
+  sources = [
+    "AsmWriter.cpp",
+    "Attributes.cpp",
+    "AutoUpgrade.cpp",
+    "BasicBlock.cpp",
+    "Comdat.cpp",
+    "ConstantFold.cpp",
+    "ConstantRange.cpp",
+    "Constants.cpp",
+    "Core.cpp",
+    "DIBuilder.cpp",
+    "DataLayout.cpp",
+    "DebugInfo.cpp",
+    "DebugInfoMetadata.cpp",
+    "DebugLoc.cpp",
+    "DiagnosticHandler.cpp",
+    "DiagnosticInfo.cpp",
+    "DiagnosticPrinter.cpp",
+    "DomTreeUpdater.cpp",
+    "Dominators.cpp",
+    "Function.cpp",
+    "GVMaterializer.cpp",
+    "Globals.cpp",
+    "IRBuilder.cpp",
+    "IRPrintingPasses.cpp",
+    "InlineAsm.cpp",
+    "Instruction.cpp",
+    "Instructions.cpp",
+    "IntrinsicInst.cpp",
+    "LLVMContext.cpp",
+    "LLVMContextImpl.cpp",
+    "LegacyPassManager.cpp",
+    "MDBuilder.cpp",
+    "Mangler.cpp",
+    "Metadata.cpp",
+    "Module.cpp",
+    "ModuleSummaryIndex.cpp",
+    "Operator.cpp",
+    "OptBisect.cpp",
+    "Pass.cpp",
+    "PassInstrumentation.cpp",
+    "PassManager.cpp",
+    "PassRegistry.cpp",
+    "PassTimingInfo.cpp",
+    "ProfileSummary.cpp",
+    "SafepointIRVerifier.cpp",
+    "Statepoint.cpp",
+    "Type.cpp",
+    "TypeFinder.cpp",
+    "Use.cpp",
+    "User.cpp",
+    "Value.cpp",
+    "ValueSymbolTable.cpp",
+    "Verifier.cpp",
+  ]
+}
Index: llvm/trunk/utils/gn/secondary/llvm/utils/TableGen/tablegen.gni
===================================================================
--- llvm/trunk/utils/gn/secondary/llvm/utils/TableGen/tablegen.gni
+++ llvm/trunk/utils/gn/secondary/llvm/utils/TableGen/tablegen.gni
@@ -0,0 +1,91 @@
+# This file defines a template for running llvm-tblgen.
+#
+# Parameters:
+#
+#   args (required)
+#       [list of strings] Flags to pass to llvm-tblgen.
+#
+#   output_name (optional)
+#       Basename of the generated output file.
+#       Defaults to target name with ".inc" appended.
+#
+#   td_file (roptional)
+#       The .td file to pass to llvm-tblgen.
+#       Defaults to target name with ".td" appended.
+#
+#   visibility (optional)
+#       GN's regular visibility attribute, see `gn help visibility`.
+#
+# Example use:
+#
+#   tablegen("attributes_compat_func_gen") {
+#     visibility = [ ":IR" ]
+#     args = [ "-gen-attrs" ]
+#     td_file = "AttributesCompatFunc.td"
+#   }
+
+template("tablegen") {
+  assert(defined(invoker.args), "args must be defined for $target_name")
+
+  config_name = "${target_name}_config"
+  config(config_name) {
+    visibility = [ ":$target_name" ]
+    include_dirs = [ target_gen_dir ]
+  }
+
+  action(target_name) {
+    forward_variables_from(invoker, [ "visibility" ])
+
+    # FIXME: In cross builds, this should depend on the host binary.
+    tblgen_target = "//llvm/utils/TableGen:llvm-tblgen"
+    tblgen_executable = get_label_info(tblgen_target, "root_out_dir") +
+                        "/bin/" + get_label_info(tblgen_target, "name")
+    deps = [
+      tblgen_target,
+    ]
+    if (defined(invoker.td_file)) {
+      td_file = invoker.td_file
+    } else {
+      td_file = "$target_name.td"
+    }
+    sources = [
+      td_file,
+    ]
+    script = "//llvm/utils/gn/build/run_tablegen.py"
+    if (defined(invoker.output_name)) {
+      gen_output = "$target_gen_dir/" + invoker.output_name
+    } else {
+      gen_output = "$target_gen_dir/$target_name.inc"
+    }
+    depfile = "$gen_output.d"
+    td_file = rebase_path(td_file, root_build_dir)
+
+    # FIXME: The cmake build lets tablegen write to a temp file and then copies
+    # it over the final output only if it has changed, for ninja's restat
+    # optimization. Instead of doing that in cmake, llvm-tblgen should do this
+    # itself. r330742 tried this, but it caused problems. Fix those and reland,
+    # so that the gn build has the optimization too.
+    args = [
+             rebase_path(tblgen_executable, root_build_dir),
+             "-I",
+             rebase_path("//llvm/include", root_build_dir),
+
+             # FIXME: Rather than duplicating this -I flag in both the CMake and
+             # the gn build, let tablegen add input dir to include search path
+             # instead?
+             "-I",
+             get_path_info(td_file, "dir"),
+             "-d",
+             rebase_path(depfile, root_build_dir),
+             "-o",
+             rebase_path(gen_output, root_build_dir),
+             td_file,
+           ] + invoker.args
+    outputs = [
+      gen_output,
+    ]
+
+    # Let targets depending on this find the generated file.
+    public_configs = [ ":$config_name" ]
+  }
+}