diff --git a/autoconf/configure.ac b/autoconf/configure.ac
index 59253c5..227aa62 100644
--- a/autoconf/configure.ac
+++ b/autoconf/configure.ac
@@ -167,7 +167,7 @@
 AC_CACHE_CHECK([target architecture],[llvm_cv_target_arch],
 [case $target in
   i?86-*)                 llvm_cv_target_arch="x86" ;;
-  amd64-* | x86_64-*)     llvm_cv_target_arch="AMD64" ;;
+  amd64-* | x86_64-*)     llvm_cv_target_arch="X86_64" ;;
   sparc*-*)               llvm_cv_target_arch="Sparc" ;;
   powerpc*-*)             llvm_cv_target_arch="PowerPC" ;;
   *)                      llvm_cv_target_arch="Unknown" ;;
@@ -211,7 +211,7 @@
     x86)     AC_SUBST(JIT,[[TARGET_HAS_JIT=1]]) ;;
     Sparc)   AC_SUBST(JIT,[[TARGET_HAS_JIT=1]]) ;;
     PowerPC) AC_SUBST(JIT,[[TARGET_HAS_JIT=1]]) ;;
-    AMD64)   AC_SUBST(JIT,[[]]) ;;
+    x86_64)  AC_SUBST(JIT,[[]]) ;;
     *)       AC_SUBST(JIT,[[]]) ;;
   esac
 fi
diff --git a/configure b/configure
index 49a5ee7..0a33a49 100755
--- a/configure
+++ b/configure
@@ -1779,7 +1779,7 @@
 else
   case $target in
   i?86-*)                 llvm_cv_target_arch="x86" ;;
-  amd64-* | x86_64-*)     llvm_cv_target_arch="AMD64" ;;
+  amd64-* | x86_64-*)     llvm_cv_target_arch="X86_64" ;;
   sparc*-*)               llvm_cv_target_arch="Sparc" ;;
   powerpc*-*)             llvm_cv_target_arch="PowerPC" ;;
   *)                      llvm_cv_target_arch="Unknown" ;;
@@ -2991,7 +2991,7 @@
  ;;
     PowerPC) JIT=TARGET_HAS_JIT=1
  ;;
-    AMD64)   JIT=
+    x86_64)  JIT=
  ;;
     *)       JIT=
  ;;