diff --git a/README.md b/README.md
index 02ffa2cc..ebb1ba7d 100644
--- a/README.md
+++ b/README.md
@@ -196,7 +196,7 @@ A shell command to run before building the wheel. This option allows you to run
 
 If dependencies are required to build your wheel (for example if you include a header from a Python module), set this to `pip install .`, and the dependencies will be installed automatically by pip. However, this means your package will be built twice - if your package takes a long time to build, you might wish to manually list the dependencies here instead.
 
-The active Python binary can be accessed using `python`, and pip with `pip`; `cibuildwheel` makes sure the right version of Python and pip will be executed.
+The active Python binary can be accessed using `python`, and pip with `pip`; `cibuildwheel` makes sure the right version of Python and pip will be executed. `{project}` can be used as a placeholder for the absolute path to the project's root.
 
 Example: `pip install .`  
 Example: `pip install pybind11`  
diff --git a/cibuildwheel/linux.py b/cibuildwheel/linux.py
index cd7a7136..e81e231a 100644
--- a/cibuildwheel/linux.py
+++ b/cibuildwheel/linux.py
@@ -103,10 +103,10 @@ def build(project_dir, package_name, output_dir, test_command, test_requires, be
             pybin_paths=' '.join(c.path+'/bin' for c in platform_configs),
             test_requires=' '.join(test_requires),
             test_command=shlex_quote(
-                test_command.format(project='/project') if test_command else ''
+                prepare_command(test_command, python='python', pip='pip', project='/project') if test_command else ''
             ),
             before_build=shlex_quote(
-                prepare_command(before_build, python='python', pip='pip') if before_build else ''
+                prepare_command(before_build, python='python', pip='pip', project='/project') if before_build else ''
             ),
             environment_exports='\n'.join(environment.as_shell_commands()),
         )
diff --git a/cibuildwheel/macos.py b/cibuildwheel/macos.py
index 73194c72..1a90c410 100644
--- a/cibuildwheel/macos.py
+++ b/cibuildwheel/macos.py
@@ -93,7 +93,7 @@ def build(project_dir, package_name, output_dir, test_command, test_requires, be
 
         # run the before_build command
         if before_build:
-            before_build_prepared = prepare_command(before_build, python='python', pip='pip')
+            before_build_prepared = prepare_command(before_build, python=python, pip=pip, project=abs_project_dir)
             call(before_build_prepared, env=env, shell=True)
 
         # build the wheel
@@ -120,8 +120,8 @@ def build(project_dir, package_name, output_dir, test_command, test_requires, be
             # run the tests from $HOME, with an absolute path in the command
             # (this ensures that Python runs the tests against the installed wheel
             # and not the repo code)
-            test_command_absolute = test_command.format(project=abs_project_dir)
-            call(shlex.split(test_command_absolute), cwd=os.environ['HOME'], env=env)
+            test_command_prepared = prepare_command(test_command, python=python, pip=pip, project=abs_project_dir)
+            call(shlex.split(test_command_prepared), cwd=os.environ['HOME'], env=env)
 
         # we're all done here; move it to output
         shutil.move(delocated_wheel, output_dir)
diff --git a/cibuildwheel/util.py b/cibuildwheel/util.py
index d860beeb..9b1e2ccf 100644
--- a/cibuildwheel/util.py
+++ b/cibuildwheel/util.py
@@ -1,7 +1,7 @@
 from fnmatch import fnmatch
 
 
-def prepare_command(command, python, pip):
+def prepare_command(command, python, pip, project):
     '''
     Preprocesses a command by expanding variables like {python} or {pip}.
 
@@ -10,7 +10,7 @@ def prepare_command(command, python, pip):
     Python 3, the user could write `{python} setup.py test`. This command would expand
     it out to python2 or python3 as appropriate.
     '''
-    return command.format(python=python, pip=pip)
+    return command.format(python=python, pip=pip, project=project)
 
 
 class BuildSkipper(object):
diff --git a/cibuildwheel/windows.py b/cibuildwheel/windows.py
index 3c962af9..42a38c80 100644
--- a/cibuildwheel/windows.py
+++ b/cibuildwheel/windows.py
@@ -78,7 +78,7 @@ def build(project_dir, package_name, output_dir, test_command, test_requires, be
 
         # run the before_build command
         if before_build:
-            before_build_prepared = prepare_command(before_build, python='python', pip='pip')
+            before_build_prepared = prepare_command(before_build, python='python', pip='pip', project=abs_project_dir)
             shell([before_build_prepared], env=env)
 
         # build the wheel
@@ -95,8 +95,8 @@ def build(project_dir, package_name, output_dir, test_command, test_requires, be
             # run the tests from c:\, with an absolute path in the command
             # (this ensures that Python runs the tests against the installed wheel
             # and not the repo code)
-            test_command_absolute = test_command.format(project=abs_project_dir)
-            shell([test_command_absolute], cwd='c:\\', env=env)
+            test_command_prepared = prepare_command(test_command, python='python', pip='pip', project=abs_project_dir)
+            shell([test_command_prepared], cwd='c:\\', env=env)
 
         # we're all done here; move it to output
         shutil.move(built_wheel, output_dir)