diff --git a/ares/configure.ac b/ares/configure.ac
index 0a6a5fcd35..1629582eef 100644
--- a/ares/configure.ac
+++ b/ares/configure.ac
@@ -148,11 +148,11 @@ CARES_SET_COMPILER_DEBUG_OPTS
 CARES_SET_COMPILER_OPTIMIZE_OPTS
 CARES_SET_COMPILER_WARNING_OPTS
 
-case $host in
-  #
-  x86_64*linux*|amd64*freebsd*|ia64*freebsd*)
-    #
-    if test "$compiler_id" = "ICC_unix"; then
+dnl case $host in
+dnl   #
+dnl   x86_64*linux*|amd64*freebsd*|ia64*freebsd*)
+dnl     #
+    if test "$compiler_id" = "INTEL_UNIX_C"; then
       #
       if test "$compiler_num" -ge "900" &&
         test "$compiler_num" -lt "1000"; then
@@ -166,9 +166,9 @@ case $host in
       fi
       #
     fi
-    ;;
-  #
-esac
+dnl     ;;
+dnl   #
+dnl esac
 
 CURL_CHECK_COMPILER_HALT_ON_ERROR
 CURL_CHECK_COMPILER_ARRAY_SIZE_NEGATIVE
diff --git a/ares/m4/cares-compilers.m4 b/ares/m4/cares-compilers.m4
index 422e13baae..9dea76b40e 100644
--- a/ares/m4/cares-compilers.m4
+++ b/ares/m4/cares-compilers.m4
@@ -16,7 +16,7 @@
 #***************************************************************************
 
 # File version for 'aclocal' use. Keep it a single number.
-# serial 38
+# serial 39
 
 
 dnl CARES_CHECK_COMPILER
@@ -563,10 +563,6 @@ AC_DEFUN([CARES_SET_COMPILER_BASIC_OPTS], [
         dnl #981: operands are evaluated in unspecified order
         dnl #1469: "cc" clobber ignored
         tmp_CPPFLAGS="$tmp_CPPFLAGS -wd 279,981,1469"
-        dnl Disable use of ANSI C aliasing rules in optimizations
-        tmp_CFLAGS="$tmp_CFLAGS -no-ansi-alias"
-        dnl Disable floating point optimizations
-        tmp_CFLAGS="$tmp_CFLAGS -fp-model precise"
         ;;
         #
       INTEL_WINDOWS_C)
@@ -930,6 +926,16 @@ AC_DEFUN([CARES_SET_COMPILER_WARNING_OPTS], [
           tmp_CFLAGS="$tmp_CFLAGS -fpstkchk"
           dnl Enable run-time detection of buffer overruns.
           tmp_CFLAGS="$tmp_CFLAGS -fstack-security-check"
+          dnl Disable use of ANSI C aliasing rules in optimizations
+          tmp_CFLAGS="$tmp_CFLAGS -no-ansi-alias"
+          dnl Disable floating point optimizations
+          tmp_CFLAGS="$tmp_CFLAGS -fp-model precise"
+          dnl Assume aliasing in the program.
+          tmp_CFLAGS="$tmp_CFLAGS -falias"
+          dnl Assume that arguments may be aliased.
+          tmp_CFLAGS="$tmp_CFLAGS -alias-args"
+          dnl Assume aliasing within functions
+          tmp_CFLAGS="$tmp_CFLAGS -ffnalias"
         fi
         ;;
         #
diff --git a/configure.ac b/configure.ac
index 91b1a3f273..789eae4c94 100644
--- a/configure.ac
+++ b/configure.ac
@@ -257,11 +257,11 @@ CURL_SET_COMPILER_DEBUG_OPTS
 CURL_SET_COMPILER_OPTIMIZE_OPTS
 CURL_SET_COMPILER_WARNING_OPTS
 
-case $host in
-  #
-  x86_64*linux*|amd64*freebsd*|ia64*freebsd*)
-    #
-    if test "$compiler_id" = "ICC_unix"; then
+dnl case $host in
+dnl   #
+dnl   x86_64*linux*|amd64*freebsd*|ia64*freebsd*)
+dnl     #
+    if test "$compiler_id" = "INTEL_UNIX_C"; then
       #
       if test "$compiler_num" -ge "900" &&
         test "$compiler_num" -lt "1000"; then
@@ -275,9 +275,9 @@ case $host in
       fi
       #
     fi
-    ;;
-  #
-esac
+dnl     ;;
+dnl   #
+dnl esac
 
 CURL_CHECK_COMPILER_HALT_ON_ERROR
 CURL_CHECK_COMPILER_ARRAY_SIZE_NEGATIVE
diff --git a/m4/curl-compilers.m4 b/m4/curl-compilers.m4
index 36d8d27748..f43b582cf7 100644
--- a/m4/curl-compilers.m4
+++ b/m4/curl-compilers.m4
@@ -22,7 +22,7 @@
 #***************************************************************************
 
 # File version for 'aclocal' use. Keep it a single number.
-# serial 37
+# serial 38
 
 
 dnl CURL_CHECK_COMPILER
@@ -569,10 +569,6 @@ AC_DEFUN([CURL_SET_COMPILER_BASIC_OPTS], [
         dnl #981: operands are evaluated in unspecified order
         dnl #1469: "cc" clobber ignored
         tmp_CPPFLAGS="$tmp_CPPFLAGS -wd 279,981,1469"
-        dnl Disable use of ANSI C aliasing rules in optimizations
-        tmp_CFLAGS="$tmp_CFLAGS -no-ansi-alias"
-        dnl Disable floating point optimizations
-        tmp_CFLAGS="$tmp_CFLAGS -fp-model precise"
         ;;
         #
       INTEL_WINDOWS_C)
@@ -936,6 +932,16 @@ AC_DEFUN([CURL_SET_COMPILER_WARNING_OPTS], [
           tmp_CFLAGS="$tmp_CFLAGS -fpstkchk"
           dnl Enable run-time detection of buffer overruns.
           tmp_CFLAGS="$tmp_CFLAGS -fstack-security-check"
+          dnl Disable use of ANSI C aliasing rules in optimizations
+          tmp_CFLAGS="$tmp_CFLAGS -no-ansi-alias"
+          dnl Disable floating point optimizations
+          tmp_CFLAGS="$tmp_CFLAGS -fp-model precise"
+          dnl Assume aliasing in the program.
+          tmp_CFLAGS="$tmp_CFLAGS -falias"
+          dnl Assume that arguments may be aliased.
+          tmp_CFLAGS="$tmp_CFLAGS -alias-args"
+          dnl Assume aliasing within functions
+          tmp_CFLAGS="$tmp_CFLAGS -ffnalias"
         fi
         ;;
         #