3 files changed, 29 insertions, 7 deletions

diff --git a/llvm/Makefile.rules b/llvm/Makefile.rules
index 66d90f12094..59d844010bb 100644
--- a/llvm/Makefile.rules
+++ b/llvm/Makefile.rules
@@ -522,13 +522,11 @@ ifdef UNIVERSAL
   # Building universal cannot compute dependencies automatically.
   DISABLE_AUTO_DEPENDENCIES=1
 else
-  ifeq ($(OS),Darwin)
-    ifeq ($(ARCH),x86_64)
-      CompileCommonOpts += -m64
-    else
-      ifeq ($(ARCH),x86)
-        CompileCommonOpts += -m32
-      endif
+  ifeq ($(ARCH),x86_64)
+    CompileCommonOpts += -m64
+  else
+    ifeq ($(ARCH),x86)
+      CompileCommonOpts += -m32
     endif
   endif
 endif
diff --git a/llvm/autoconf/configure.ac b/llvm/autoconf/configure.ac
index d6c89e36009..1ef8536412d 100644
--- a/llvm/autoconf/configure.ac
+++ b/llvm/autoconf/configure.ac
@@ -233,6 +233,13 @@ if test "$llvm_cv_target_arch" = "Unknown" ; then
   AC_MSG_WARN([Configuring LLVM for an unknown target archicture])
 fi
 
+if test "$llvm_cv_os_type" = "Linux" -a "$llvm_cv_target_arch" = "x86_64" ; then
+  AC_IS_LINUX_MIXED
+  if test "$llvm_cv_linux_mixed" = "yes"; then
+    llvm_cv_target_arch="x86"
+  fi
+fi
+
 dnl Define a substitution, ARCH, for the target architecture
 AC_SUBST(ARCH,$llvm_cv_target_arch)
 
diff --git a/llvm/autoconf/m4/linux_mixed_64_32.m4 b/llvm/autoconf/m4/linux_mixed_64_32.m4
new file mode 100644
index 00000000000..7c781ac2801
--- /dev/null
+++ b/llvm/autoconf/m4/linux_mixed_64_32.m4
@@ -0,0 +1,17 @@
+#
+# Some Linux machines run a 64-bit kernel with a 32-bit userspace. 'uname -m'
+# shows these at x86_64, so in that case, ask the system 'gcc' what it thinks.
+#
+AC_DEFUN([AC_IS_LINUX_MIXED],
+[AC_CACHE_CHECK(for 32-bit userspace on 64-bit system,llvm_cv_linux_mixed,
+[ AC_LANG_PUSH([C])
+  AC_COMPILE_IFELSE([AC_LANG_PROGRAM(
+      [[#ifndef __x86_64__
+       error: Not x86-64 even if uname says so!
+      #endif
+      ]])],
+      [llvm_cv_linux_mixed=no],
+      [llvm_cv_linux_mixed=yes])
+  AC_LANG_POP([C])
+])
+])