build-script: Allowing passing of libtool path to llvm.

utils/build-script

@@ -784,6 +784,11 @@ class BuildScriptInvocation(object):
                 "--host-lipo", toolchain.lipo,
             ]
 
+        if toolchain.libtool is not None:
+            impl_args += [
+                "--host-libtool", toolchain.libtool,
+            ]
+
         # If we have extra_swift_args, combine all of them together and then
         # add them as one command.
         if args.extra_swift_args:
@@ -1937,6 +1942,11 @@ iterations with -O",
         help="the absolute path to lipo. Default is auto detected.",
         type=arguments.type.executable,
         metavar="PATH")
+    parser.add_argument(
+        "--host-libtool",
+        help="the absolute path to libtool. Default is auto detected.",
+        type=arguments.type.executable,
+        metavar="PATH")
     parser.add_argument(
         "--distcc",
         help="use distcc in pump mode",
@@ -2116,6 +2126,8 @@ iterations with -O",
         toolchain.cxx = args.host_cxx
     if args.host_lipo is not None:
         toolchain.lipo = args.host_lipo
+    if args.host_libtool is not None:
+        toolchain.libtool = args.host_libtool
     if args.cmake is not None:
         toolchain.cmake = args.cmake
 

utils/build-script-impl

@@ -48,6 +48,7 @@ KNOWN_SETTINGS=(
     host-cc                     ""               "the path to CC, the 'clang' compiler for the host platform. **This argument is required**"
     host-cxx                    ""               "the path to CXX, the 'clang++' compiler for the host platform. **This argument is required**"
     host-lipo                   ""               "the path to lipo for creating universal binaries on Darwin"
+    host-libtool                ""               "the path to libtool"
     darwin-xcrun-toolchain      "default"        "the name of the toolchain to use on Darwin"
     ninja-bin                   ""               "the path to Ninja tool"
     cmark-build-type            "Debug"          "the CMake build variant for CommonMark (Debug, RelWithDebInfo, Release, MinSizeRel).  Defaults to Debug."
@@ -1987,6 +1988,13 @@ for host in "${ALL_HOSTS[@]}"; do
                     build_targets=(llvm-tblgen clang-headers)
                 fi
 
+                if [ "${HOST_LIBTOOL}" ] ; then
+                    cmake_options=(
+                        "${cmake_options[@]}"
+                        -DCMAKE_LIBTOOL:PATH="${HOST_LIBTOOL}"
+                    )
+                fi
+
                 # Note: we set the variable:
                 #
                 # LLVM_TOOL_SWIFT_BUILD

utils/swift_build_support/swift_build_support/toolchain.py

@@ -52,6 +52,7 @@ def _getter(self):
 _register("llvm_profdata", "llvm-profdata")
 _register("llvm_cov", "llvm-cov")
 _register("lipo", "lipo")
+_register("libtool", "libtool")
 
 
 class Darwin(Toolchain):