diff --git a/typed-racket-lib/typed-racket/typecheck/tc-lambda-unit.rkt b/typed-racket-lib/typed-racket/typecheck/tc-lambda-unit.rkt
index e7e90c6b..2891ee80 100644
--- a/typed-racket-lib/typed-racket/typecheck/tc-lambda-unit.rkt
+++ b/typed-racket-lib/typed-racket/typecheck/tc-lambda-unit.rkt
@@ -58,12 +58,16 @@
 ;; raw-rest: Either #f for no rest argument or (list rest-id rest-type) where rest-id is the
 ;;           identifier of the rest arg, and rest-type is the type.
 ;; expected: The expected type of the body forms.
+;; body-type: if provided, the result of type checking the body (because someone else already did it)
 ;; body: The body of the lambda to typecheck.
 (define/cond-contract
-  (tc-lambda-body arg-names arg-types #:rest [raw-rest #f] #:expected [expected #f] body)
+  (tc-lambda-body arg-names arg-types #:rest [raw-rest #f] #:expected [expected #f]
+                  #:body-type [body-type #f]
+                  body)
   (->* ((listof identifier?) (listof Type/c) syntax?)
        (#:rest (or/c #f (list/c identifier? (or/c Type/c (cons/c Type/c symbol?))))
-        #:expected (or/c #f tc-results/c))
+        #:expected (or/c #f tc-results/c)
+        #:body-type (or/c #f tc-results/c))
        arr?)
   (define-values (rest-id rest)
     (if raw-rest
@@ -84,7 +88,7 @@
       (with-lexical-env/extend-types
         (append rest-names arg-names)
         (append rest-types arg-types)
-        (tc-body/check body expected))
+        (or body-type (tc-body/check body expected)))
       arg-names #:rest-id rest-id)
     #:rest (and (Type? rest) rest)
     #:drest (and (cons? rest) rest)))
@@ -236,14 +240,14 @@
           (get-type rest-id #:default Univ)]
          ;; Lambda with no rest argument
          [else #f]))
+     (define body-t (and eta-expanded? (tc-expr eta-expanded?)))
      (cond 
       ;; special case for un-annotated eta-expansions
       [(and eta-expanded? (not rest-id) (andmap not arg-types)
             ;; FIXME: should also handle polymorphic types
             ;; but we can't return anything but a (listof arr?) here 
-            ;; FIXME: sometimes will typecheck the relevant code twice if it doesn't match
-            ;; FIXME: misses optimization opportunities of this code
-            (match (tc-expr eta-expanded?)
+            ;; FIXME: misses optimization opportunities in this code
+            (match body-t
               [(tc-result1: (Function: arrs))
                (define possibles (for*/list ([arr (in-list arrs)]
                                              [restricted (in-value (restrict-to-arity arr (length arg-list)))]
@@ -261,6 +265,7 @@
        (list
         (tc-lambda-body arg-list (map (lambda (v) (or v Univ)) arg-types)
                         #:rest (and rest-type (list rest-id rest-type))
+                        #:body-type body-t
                         body))])]))