diff --git a/gcc/fortran/ChangeLog b/gcc/fortran/ChangeLog
index 2156e716bdb..64f58e85c2d 100644
--- a/gcc/fortran/ChangeLog
+++ b/gcc/fortran/ChangeLog
@@ -1,3 +1,12 @@
+2011-10-10  Thomas Koenig  <tkoenig@gcc.gnu.org>
+
+	PR fortran/50564
+	* frontend-passes (forall_level):  New variable.
+	(cfe_register_funcs):  Don't register functions if we
+	are within a forall loop.
+	(optimize_namespace):  Set forall_level to 0 before entry.
+	(gfc_code_walker):  Increase/decrease forall_level.
+
 2011-10-09  Tobias Burnus  <burnus@net-b.de>
 
 	PR fortran/45044
diff --git a/gcc/fortran/frontend-passes.c b/gcc/fortran/frontend-passes.c
index 16053e0742a..dcbaf06d170 100644
--- a/gcc/fortran/frontend-passes.c
+++ b/gcc/fortran/frontend-passes.c
@@ -62,6 +62,10 @@ static gfc_code *inserted_block, **changed_statement;
 
 gfc_namespace *current_ns;
 
+/* If we are within any forall loop.  */
+
+static int forall_level;
+
 /* Entry point - run all passes for a namespace.  So far, only an
    optimization pass is run.  */
 
@@ -165,6 +169,12 @@ cfe_register_funcs (gfc_expr **e, int *walk_subtrees ATTRIBUTE_UNUSED,
 	  || (*e)->ts.u.cl->length->expr_type != EXPR_CONSTANT))
     return 0;
 
+  /* We don't do function elimination within FORALL statements, it can
+     lead to wrong-code in certain circumstances.  */
+
+  if (forall_level > 0)
+    return 0;
+
   /* If we don't know the shape at compile time, we create an allocatable
      temporary variable to hold the intermediate result, but only if
      allocation on assignment is active.  */
@@ -493,6 +503,7 @@ optimize_namespace (gfc_namespace *ns)
 {
 
   current_ns = ns;
+  forall_level = 0;
 
   gfc_code_walker (&ns->code, convert_do_while, dummy_expr_callback, NULL);
   gfc_code_walker (&ns->code, cfe_code, cfe_expr_0, NULL);
@@ -1193,6 +1204,8 @@ gfc_code_walker (gfc_code **c, walk_code_fn_t codefn, walk_expr_fn_t exprfn,
 		    WALK_SUBEXPR (fa->end);
 		    WALK_SUBEXPR (fa->stride);
 		  }
+		if (co->op == EXEC_FORALL)
+		  forall_level ++;
 		break;
 	      }
 
@@ -1335,6 +1348,10 @@ gfc_code_walker (gfc_code **c, walk_code_fn_t codefn, walk_expr_fn_t exprfn,
 	      WALK_SUBEXPR (b->expr2);
 	      WALK_SUBCODE (b->next);
 	    }
+
+	  if (co->op == EXEC_FORALL)
+	    forall_level --;
+
 	}
     }
   return 0;
diff --git a/gcc/testsuite/ChangeLog b/gcc/testsuite/ChangeLog
index faa52acc03c..1be870bbd3d 100644
--- a/gcc/testsuite/ChangeLog
+++ b/gcc/testsuite/ChangeLog
@@ -1,3 +1,8 @@
+2011-10-10  Thomas Koenig  <tkoenig@gcc.gnu.org>
+
+	PR fortran/50564
+	* gfortran.dg/forall_15.f90:  New test case.
+
 2011-10-10  Aldy Hernandez  <aldyh@redhat.com>
 	    Andrew Macleod  <amacleod@redhat.com>
 
diff --git a/gcc/testsuite/gfortran.dg/forall_15.f90 b/gcc/testsuite/gfortran.dg/forall_15.f90
new file mode 100644
index 00000000000..c875e033312
--- /dev/null
+++ b/gcc/testsuite/gfortran.dg/forall_15.f90
@@ -0,0 +1,26 @@
+! { dg-do run }
+! { dg-options "-ffrontend-optimize -fdump-tree-original" }
+! PR 50564 - this used to ICE with front end optimization.
+! Original test case by Andrew Benson.
+program test
+  implicit none
+  double precision, dimension(2) :: timeSteps, control
+  integer                        :: iTime
+  double precision               :: ratio
+  double precision               :: a
+
+  ratio = 0.7d0
+  control(1) = ratio**(dble(1)-0.5d0)-ratio**(dble(1)-1.5d0)
+  control(2) = ratio**(dble(2)-0.5d0)-ratio**(dble(2)-1.5d0)
+  forall(iTime=1:2)
+     timeSteps(iTime)=ratio**(dble(iTime)-0.5d0)-ratio**(dble(iTime)-1.5d0)
+  end forall
+  if (any(abs(timesteps - control) > 1d-10)) call abort
+
+  ! Make sure we still do the front-end optimization after a forall
+  a = cos(ratio)*cos(ratio) + sin(ratio)*sin(ratio)
+  if (abs(a-1.d0) > 1d-10) call abort
+end program test
+! { dg-final { scan-tree-dump-times "__builtin_cos" 1 "original" } }
+! { dg-final { scan-tree-dump-times "__builtin_sin" 1 "original" } }
+! { dg-final { cleanup-tree-dump "original" } }