diff --git a/news/2195.feature b/news/2195.feature
new file mode 100644
index 00000000000..947d6cd2f36
--- /dev/null
+++ b/news/2195.feature
@@ -0,0 +1 @@
+Add supporte for a `PIP_IGNORE` environment setting, which, when pointing to a valid file, causes `pip install` to ignore all file patterns listed in there.  This can speed up installations from large source trees.
diff --git a/src/pip/_internal/download.py b/src/pip/_internal/download.py
index d56a1bb3bb2..4671857135b 100644
--- a/src/pip/_internal/download.py
+++ b/src/pip/_internal/download.py
@@ -690,11 +690,23 @@ def unpack_file_url(link, location, download_dir=None, hashes=None):
     """
     link_path = url_to_path(link.url_without_fragment)
 
+    # if a .pipignore' file location is set and exists, '#' style
+    # comments are stripped.  All other strings (space limited) are interpreted
+    # as glob-style pattersn to be passed to `shutil.copytree`, and are thus
+    # excluded from the file cloning operation.
+    ignored = list()
+    pipignore = os.environ.get('PIP_IGNORE')
+    if pipignore and os.path.isfile(pipignore):
+        with open(pipignore, 'r') as fin:
+            for line in fin.readlines():
+                ignored.extend(line.split('#')[0].strip().split())
+
     # If it's a url to a local directory
     if is_dir_url(link):
         if os.path.isdir(location):
             rmtree(location)
-        shutil.copytree(link_path, location, symlinks=True)
+        shutil.copytree(link_path, location, symlinks=True,
+                        ignore=shutil.ignore_patterns(*ignored))
         if download_dir:
             logger.info('Link is a directory, ignoring download_dir')
         return