diff --git a/src/sf/subst.scm b/src/sf/subst.scm
index 6fa6ac5..e0773d7 100644
--- a/src/sf/subst.scm
+++ b/src/sf/subst.scm
@@ -453,15 +453,23 @@ you ask for.
 	 (combination/optimizing-make
 	  expression
 	  block
-	  (if (procedure? operator)
-	      (integrate/procedure-operator operations environment
-					    block operator operands)
-	      (let ((operator
-		     (integrate/expression operations environment operator)))
-		(if (procedure? operator)
+	  (let* ((integrate-procedure
+		  (lambda (operator)
 		    (integrate/procedure-operator operations environment
-						  block operator operands)
-		    operator)))
+						  block operator operands)))
+		 (operator
+		  (if (procedure? operator)
+		      (integrate-procedure operator)
+		      (let ((operator
+			     (integrate/expression operations
+						   environment
+						   operator)))
+			(if (procedure? operator)
+			    (integrate-procedure operator)
+			    operator)))))
+	    (cond ((integrate/combination-operator operator operands)
+		   => integrate-procedure)
+		  (else operator)))
 	  operands))))
 
 (define (integrate/procedure-operator operations environment
@@ -490,6 +498,85 @@ you ask for.
 	  (else (error "Unknown operation" operation))))
       integration-failure)))
 
+;;; ((let ((a (foo)) (b (bar)))
+;;;    (lambda (receiver)
+;;;      ...body...))
+;;;  (lambda (x y z) ...))
+;;; =>
+;;; (let ((receiver (lambda (x y z) ...)))
+;;;   (let ((a (foo)) (b (bar)))
+;;;     ...body...))
+;;;
+;;; We do this transformation only if the operands of the original
+;;; combination have no side effects, so that this transformation does
+;;; not have the consequence of committing to a particular order of
+;;; evaluation when the original program didn't request one.  If we
+;;; did commit to a particular order of evaluation, we could transform
+;;; not just LETs in operator positions but BEGINs as well, by adding
+;;; a clause in SUBLOOP's COND.  However, this is mainly for VALUES
+;;; and CALL-WITH-VALUES, which will produce only LETs in operator
+;;; positions and only LAMBDAs in the respective operand positions.
+;;;
+;;; INTEGRATE/COMBINATION-OPERATOR takes any expression (usually from
+;;; an operator position), and, if it is a combination of the above
+;;; form, returns a procedure expression that is equivalent to it if
+;;; used in an operator position; or if it is not a combination of the
+;;; above form, returns #F.
+
+(define (integrate/combination-operator operator operands)
+  (and (combination? operator)
+       (for-all? operands non-side-effecting?)
+       (let loop ((operator operator) (encloser (lambda (body) body)))
+	 (let ((operator* (combination/operator operator)))
+	   (cond ((if (procedure? operator*)
+		      operator*
+		      (integrate/combination-operator
+		       operator*
+		       (combination/operands operator)))
+		  => (lambda (operator*)
+		       (let subloop
+			   ((body (procedure/body operator*))
+			    (encloser
+			     (lambda (body*)
+			       (encloser
+				(combination-with-operator
+				 operator
+				 (procedure-with-body operator* body*))))))
+			 (cond ((combination? body) (loop body encloser))
+			       ((procedure? body)
+				(procedure-with-body
+				 body
+				 (encloser (procedure/body body))))
+			       ((declaration? body)
+				(subloop (declaration/expression body)
+					 (lambda (body*)
+					   (encloser
+					    (declaration/make
+					     (declaration/scode body)
+					     (declaration/declarations body)
+					     body*)))))
+			       (else #f)))))
+		 (else #f))))))
+
+(define (combination-with-operator combination operator)
+  (combination/make (combination/scode combination)
+		    (combination/block combination)
+		    operator
+		    (combination/operands combination)))
+
+(define (procedure-with-body procedure body)
+  (procedure/make (procedure/scode procedure)
+		  (procedure/block procedure)
+		  (procedure/name procedure)
+		  (procedure/required procedure)
+		  (procedure/optional procedure)
+		  (procedure/rest procedure)
+		  body))
+
+(define (non-side-effecting? expression)
+  (or (reference? expression)
+      (non-side-effecting-in-sequence? expression)))
+
 (define-method/integrate 'DECLARATION
   (lambda (operations environment declaration)
     (let ((declarations (declaration/declarations declaration))
diff --git a/src/sf/usiexp.scm b/src/sf/usiexp.scm
index 5d50463..d596073 100644
--- a/src/sf/usiexp.scm
+++ b/src/sf/usiexp.scm
@@ -351,7 +351,7 @@ USA.
       (make-combination expr block (ucode-primitive cons)
 			(list (car rest)
 			      (list-expansion-loop #f block (cdr rest))))))
-
+
 (define (values-expansion expr operands if-expanded if-not-expanded block)
   if-not-expanded
   (if-expanded
@@ -373,12 +373,18 @@ USA.
 	   (let ((variable (variable/make&bind! block 'RECEIVER)))
 	     (procedure/make
 	      #f block lambda-tag:unnamed (list variable) '() #f
-	      (combination/make #f
-				block
-				(reference/make #f block variable)
-				(map (lambda (variable)
-				       (reference/make #f block variable))
-				     variables))))))
+	      (declaration/make
+	       #f
+	       ;; The receiver is used only once, and all its operand
+	       ;; expressions are effect-free, so integrating here is
+	       ;; safe.
+	       (declarations/parse block '((INTEGRATE-OPERATOR RECEIVER)))
+	       (combination/make #f
+				 block
+				 (reference/make #f block variable)
+				 (map (lambda (variable)
+					(reference/make #f block variable))
+				      variables)))))))
 	operands)))))
 
 (define (call-with-values-expansion expr operands