diff --git a/gcc/ChangeLog b/gcc/ChangeLog
index 7fd95bcdda1..e7d95c74b28 100644
--- a/gcc/ChangeLog
+++ b/gcc/ChangeLog
@@ -1,3 +1,9 @@
+2009-03-27  H.J. Lu  <hongjiu.lu@intel.com>
+
+	PR middle-end/39315
+	* cfgexpand.c (expand_one_stack_var_at): Change alignment
+	limit to MAX_SUPPORTED_STACK_ALIGNMENT.
+
 2009-03-27  Richard Guenther  <rguenther@suse.de>
 
 	PR tree-optimization/39120
diff --git a/gcc/cfgexpand.c b/gcc/cfgexpand.c
index 4bfdc5fed74..695e4ef0ef9 100644
--- a/gcc/cfgexpand.c
+++ b/gcc/cfgexpand.c
@@ -866,7 +866,8 @@ dump_stack_var_partition (void)
 static void
 expand_one_stack_var_at (tree decl, HOST_WIDE_INT offset)
 {
-  HOST_WIDE_INT align;
+  /* Alignment is unsigned.   */
+  unsigned HOST_WIDE_INT align;
   rtx x;
 
   /* If this fails, we've overflowed the stack frame.  Error nicely?  */
@@ -879,8 +880,10 @@ expand_one_stack_var_at (tree decl, HOST_WIDE_INT offset)
   offset -= frame_phase;
   align = offset & -offset;
   align *= BITS_PER_UNIT;
-  if (align > STACK_BOUNDARY || align == 0)
+  if (align == 0)
     align = STACK_BOUNDARY;
+  else if (align > MAX_SUPPORTED_STACK_ALIGNMENT)
+    align = MAX_SUPPORTED_STACK_ALIGNMENT;
   DECL_ALIGN (decl) = align;
   DECL_USER_ALIGN (decl) = 0;
 
diff --git a/gcc/testsuite/ChangeLog b/gcc/testsuite/ChangeLog
index 5fea6b9c9f4..ff739aca938 100644
--- a/gcc/testsuite/ChangeLog
+++ b/gcc/testsuite/ChangeLog
@@ -8,6 +8,15 @@
 	PR tree-optimization/39120
 	* gcc.dg/torture/pta-callused-1.c: New testcase.
 
+2009-03-27  H.J. Lu  <hongjiu.lu@intel.com>
+
+	PR middle-end/39315
+	* gcc.target/i386/pr39315-1.c: New.
+	* gcc.target/i386/pr39315-2.c: Likewise.
+	* gcc.target/i386/pr39315-3.c: Likewise.
+	* gcc.target/i386/pr39315-4.c: Likewise.
+	* gcc.target/i386/pr39315-check.c: Likewise.
+
 2009-03-27  H.J. Lu  <hongjiu.lu@intel.com>
 
 	PR c/39323
diff --git a/gcc/testsuite/gcc.target/i386/pr39315-1.c b/gcc/testsuite/gcc.target/i386/pr39315-1.c
new file mode 100644
index 00000000000..16ba5d59fe4
--- /dev/null
+++ b/gcc/testsuite/gcc.target/i386/pr39315-1.c
@@ -0,0 +1,18 @@
+/* PR middle-end/39315  */
+/* { dg-do compile } */
+/* { dg-options "-O -msse2 -mtune=generic" } */
+/* { dg-final { scan-assembler-not "movups" } } */
+/* { dg-final { scan-assembler-not "movlps" } } */
+/* { dg-final { scan-assembler-not "movhps" } } */
+/* { dg-final { scan-assembler "movaps" } } */
+
+typedef float __m128 __attribute__ ((__vector_size__ (16)));
+
+extern void bar (__m128 *);
+
+void
+foo (__m128 *x)
+{
+  __m128 b = *x;
+  bar (&b);
+}
diff --git a/gcc/testsuite/gcc.target/i386/pr39315-2.c b/gcc/testsuite/gcc.target/i386/pr39315-2.c
new file mode 100644
index 00000000000..ab3dcd0d24a
--- /dev/null
+++ b/gcc/testsuite/gcc.target/i386/pr39315-2.c
@@ -0,0 +1,15 @@
+/* PR middle-end/39315  */
+/* { dg-do run } */
+/* { dg-options "-O -msse2 -mtune=generic" } */
+/* { dg-additional-sources pr39315-check.c } */
+
+typedef float __m128 __attribute__ ((__vector_size__ (16)));
+
+extern void bar (__m128 *, int);
+
+void
+foo (__m128 *x)
+{
+  __m128 b = *x;
+  bar (&b, __alignof__ (x));
+}
diff --git a/gcc/testsuite/gcc.target/i386/pr39315-3.c b/gcc/testsuite/gcc.target/i386/pr39315-3.c
new file mode 100644
index 00000000000..07862db603a
--- /dev/null
+++ b/gcc/testsuite/gcc.target/i386/pr39315-3.c
@@ -0,0 +1,19 @@
+/* PR middle-end/39315  */
+/* { dg-do compile } */
+/* { dg-options "-O -msse2 -mtune=generic" } */
+/* { dg-final { scan-assembler-not "movups" } } */
+/* { dg-final { scan-assembler-not "movlps" } } */
+/* { dg-final { scan-assembler-not "movhps" } } */
+/* { dg-final { scan-assembler "and\[lq\]?\[\\t \]*\\$-128,\[\\t \]*%\[re\]?sp" } } */
+/* { dg-final { scan-assembler "movaps" } } */
+
+typedef float __m128 __attribute__ ((__vector_size__ (16)));
+
+extern void bar (__m128 *);
+
+void
+foo (__m128 *x)
+{
+  __m128 b  __attribute__ ((aligned(128))) = *x;
+  bar (&b);
+}
diff --git a/gcc/testsuite/gcc.target/i386/pr39315-4.c b/gcc/testsuite/gcc.target/i386/pr39315-4.c
new file mode 100644
index 00000000000..2e55c251b03
--- /dev/null
+++ b/gcc/testsuite/gcc.target/i386/pr39315-4.c
@@ -0,0 +1,15 @@
+/* PR middle-end/39315  */
+/* { dg-do run } */
+/* { dg-options "-O -msse2 -mtune=generic" } */
+/* { dg-additional-sources pr39315-check.c } */
+
+typedef float __m128 __attribute__ ((__vector_size__ (16)));
+
+extern void bar (__m128 *, int);
+
+void
+foo (__m128 *x)
+{
+  __m128 b __attribute__ ((aligned(128))) = *x;
+  bar (&b, __alignof__ (x));
+}
diff --git a/gcc/testsuite/gcc.target/i386/pr39315-check.c b/gcc/testsuite/gcc.target/i386/pr39315-check.c
new file mode 100644
index 00000000000..ff926057536
--- /dev/null
+++ b/gcc/testsuite/gcc.target/i386/pr39315-check.c
@@ -0,0 +1,22 @@
+typedef float __m128 __attribute__ ((__vector_size__ (16)));
+
+extern void foo (__m128 *);
+extern void abort (void);
+
+__m128 y = { 0.0, 1.0, 2.0, 3.0 };
+
+void
+bar (__m128 *x, int align)
+{
+  if ((((__PTRDIFF_TYPE__) x) & (align - 1)) != 0)
+    abort ();
+  if (__builtin_memcmp (x, &y, sizeof (y)) != 0)
+    abort ();
+}
+
+int
+main ()
+{
+  foo (&y);
+  return 0;
+}