diff --git a/poetry/masonry/builders/editable.py b/poetry/masonry/builders/editable.py
index 21a5d049f08..5c32fcb57e1 100644
--- a/poetry/masonry/builders/editable.py
+++ b/poetry/masonry/builders/editable.py
@@ -43,16 +43,24 @@ def build(self):
         )
 
         if self._package.build_script:
-            self._debug(
-                "  - <warning>Falling back on using a <b>setup.py</b></warning>"
-            )
-            return self._setup_build()
+            if self._package.build_should_generate_setup():
+                self._debug(
+                    "  - <warning>Falling back on using a <b>setup.py</b></warning>"
+                )
+
+                return self._setup_build()
+
+            self._run_build_script(self._package.build_script)
 
         added_files = []
         added_files += self._add_pth()
         added_files += self._add_scripts()
         self._add_dist_info(added_files)
 
+    def _run_build_script(self, build_script):
+        self._debug("  - Executing build script: <b>{}</b>".format(build_script))
+        self._env.run("python", str(self._path.joinpath(build_script)), call=True)
+
     def _setup_build(self):
         builder = SdistBuilder(self._poetry)
         setup = self._path / "setup.py"
diff --git a/tests/fixtures/extended_project_without_setup/README.rst b/tests/fixtures/extended_project_without_setup/README.rst
new file mode 100644
index 00000000000..f7fe15470f9
--- /dev/null
+++ b/tests/fixtures/extended_project_without_setup/README.rst
@@ -0,0 +1,2 @@
+My Package
+==========
diff --git a/tests/fixtures/extended_project_without_setup/build.py b/tests/fixtures/extended_project_without_setup/build.py
new file mode 100644
index 00000000000..e69de29bb2d
diff --git a/tests/fixtures/extended_project_without_setup/extended_project/__init__.py b/tests/fixtures/extended_project_without_setup/extended_project/__init__.py
new file mode 100644
index 00000000000..e69de29bb2d
diff --git a/tests/fixtures/extended_project_without_setup/pyproject.toml b/tests/fixtures/extended_project_without_setup/pyproject.toml
new file mode 100644
index 00000000000..42375c03c25
--- /dev/null
+++ b/tests/fixtures/extended_project_without_setup/pyproject.toml
@@ -0,0 +1,32 @@
+[tool.poetry]
+name = "extended-project"
+version = "1.2.3"
+description = "Some description."
+authors = [
+    "Sébastien Eustace <sebastien@eustace.io>"
+]
+license = "MIT"
+
+readme = "README.rst"
+
+homepage = "https://python-poetry.org"
+repository = "https://github.com/python-poetry/poetry"
+documentation = "https://python-poetry.org/docs"
+
+keywords = ["packaging", "dependency", "poetry"]
+
+classifiers = [
+    "Topic :: Software Development :: Build Tools",
+    "Topic :: Software Development :: Libraries :: Python Modules"
+]
+
+[tool.poetry.build]
+script = "build.py"
+generate-setup-file = false
+
+# Requirements
+[tool.poetry.dependencies]
+python = "~2.7 || ^3.4"
+
+[tool.poetry.scripts]
+foo = "foo:bar"
diff --git a/tests/masonry/builders/test_editable_builder.py b/tests/masonry/builders/test_editable_builder.py
index 05688f5a6bb..e2aac5beb41 100644
--- a/tests/masonry/builders/test_editable_builder.py
+++ b/tests/masonry/builders/test_editable_builder.py
@@ -42,6 +42,17 @@ def extended_poetry():
     return poetry
 
 
+@pytest.fixture()
+def extended_without_setup_poetry():
+    poetry = Factory().create_poetry(
+        Path(__file__).parent.parent.parent
+        / "fixtures"
+        / "extended_project_without_setup"
+    )
+
+    return poetry
+
+
 @pytest.fixture()
 def env_manager(simple_poetry):
     return EnvManager(simple_poetry)
@@ -194,3 +205,14 @@ def test_builder_installs_proper_files_when_packages_configured(
 
     assert paths.issubset(expected)
     assert len(paths) == len(expected)
+
+
+def test_builder_should_execute_build_scripts(extended_without_setup_poetry):
+    env = MockEnv(path=Path("/foo"))
+    builder = EditableBuilder(extended_without_setup_poetry, env, NullIO())
+
+    builder.build()
+
+    assert [
+        ["python", str(extended_without_setup_poetry.file.parent / "build.py")]
+    ] == env.executed