diff --git a/Documentation/gitdiffcore.txt b/Documentation/gitdiffcore.txt
index 2bdbc3d4f6..e8041bc08f 100644
--- a/Documentation/gitdiffcore.txt
+++ b/Documentation/gitdiffcore.txt
@@ -36,11 +36,25 @@ files:
 
  - 'git-diff-tree' compares contents of two "tree" objects;
 
-In all of these cases, the commands themselves compare
-corresponding paths in the two sets of files.  The result of
-comparison is passed from these commands to what is internally
-called "diffcore", in a format similar to what is output when
-the -p option is not used.  E.g.
+In all of these cases, the commands themselves first optionally limit
+the two sets of files by any pathspecs given on their command-lines,
+and compare corresponding paths in the two resulting sets of files.
+
+The pathspecs are used to limit the world diff operates in.  They remove
+the filepairs outside the specified sets of pathnames.  E.g. If the
+input set of filepairs included:
+
+------------------------------------------------
+:100644 100644 bcd1234... 0123456... M junkfile
+------------------------------------------------
+
+but the command invocation was `git diff-files myfile`, then the
+junkfile entry would be removed from the list because only "myfile"
+is under consideration.
+
+The result of comparison is passed from these commands to what is
+internally called "diffcore", in a format similar to what is output
+when the -p option is not used.  E.g.
 
 ------------------------------------------------
 in-place edit  :100644 100644 bcd1234... 0123456... M file0
@@ -52,9 +66,8 @@ unmerged       :000000 000000 0000000... 0000000... U file6
 The diffcore mechanism is fed a list of such comparison results
 (each of which is called "filepair", although at this point each
 of them talks about a single file), and transforms such a list
-into another list.  There are currently 6 such transformations:
+into another list.  There are currently 5 such transformations:
 
-- diffcore-pathspec
 - diffcore-break
 - diffcore-rename
 - diffcore-merge-broken
@@ -62,38 +75,14 @@ into another list.  There are currently 6 such transformations:
 - diffcore-order
 
 These are applied in sequence.  The set of filepairs 'git-diff-{asterisk}'
-commands find are used as the input to diffcore-pathspec, and
-the output from diffcore-pathspec is used as the input to the
+commands find are used as the input to diffcore-break, and
+the output from diffcore-break is used as the input to the
 next transformation.  The final result is then passed to the
 output routine and generates either diff-raw format (see Output
 format sections of the manual for 'git-diff-{asterisk}' commands) or
 diff-patch format.
 
 
-diffcore-pathspec: For Ignoring Files Outside Our Consideration
----------------------------------------------------------------
-
-The first transformation in the chain is diffcore-pathspec, and
-is controlled by giving the pathname parameters to the
-'git-diff-{asterisk}' commands on the command line.  The pathspec is used
-to limit the world diff operates in.  It removes the filepairs
-outside the specified set of pathnames.  E.g. If the input set
-of filepairs included:
-
-------------------------------------------------
-:100644 100644 bcd1234... 0123456... M junkfile
-------------------------------------------------
-
-but the command invocation was `git diff-files myfile`, then the
-junkfile entry would be removed from the list because only "myfile"
-is under consideration.
-
-Implementation note.  For performance reasons, 'git-diff-tree'
-uses the pathname parameters on the command line to cull set of
-filepairs it feeds the diffcore mechanism itself, and does not
-use diffcore-pathspec, but the end result is the same.
-
-
 diffcore-break: For Splitting Up "Complete Rewrites"
 ----------------------------------------------------
 
diff --git a/diffcore.h b/diffcore.h
index cc96c20734..8ae35785fd 100644
--- a/diffcore.h
+++ b/diffcore.h
@@ -92,7 +92,6 @@ extern struct diff_filepair *diff_queue(struct diff_queue_struct *,
 					struct diff_filespec *);
 extern void diff_q(struct diff_queue_struct *, struct diff_filepair *);
 
-extern void diffcore_pathspec(const char **pathspec);
 extern void diffcore_break(int);
 extern void diffcore_rename(struct diff_options *);
 extern void diffcore_merge_broken(void);