diff --git a/ci/travis/ci.sh b/ci/travis/ci.sh
index 9eb785c98..8e639933a 100755
--- a/ci/travis/ci.sh
+++ b/ci/travis/ci.sh
@@ -104,6 +104,13 @@ upload_wheels() {
       fi
     done
   fi
+  (
+    cd "${WORKSPACE_DIR}"/python
+    if ! python -s -c "import ray, sys; sys.exit(0 if ray._raylet.OPTIMIZED else 1)"; then
+      echo "ERROR: Uploading non-optimized wheels! Performance will suffer for users!"
+      false
+    fi
+  )
 }
 
 test_core() {
diff --git a/doc/source/development.rst b/doc/source/development.rst
index 4c0867fd1..1b306ba70 100644
--- a/doc/source/development.rst
+++ b/doc/source/development.rst
@@ -23,7 +23,7 @@ changes you make to files in the Ray directory will not have any effect.
 
 If you run into **Permission Denied** errors when running ``pip install``,
 you can try adding ``--user``. You may also need to run something like ``sudo
-chown -R $USER $HOME/anaconda3`` (substituting in the appropriate path).
+chown -R "$USER" ~/anaconda3`` (substituting in the appropriate path).
 
 If you make changes to the C++ or Python files, you will need to run the
 build so C++ code is recompiled and/or Python files are redeployed in
@@ -38,6 +38,35 @@ the following:
 This command is not enough to recompile all C++ unit tests. To do so, see
 `Testing locally`_.
 
+Fast, Debug, and Optimized Builds
+---------------------------------
+
+Currently, Ray is built with optimizations, which can take a long time and
+interfere with debugging. To perform fast, debug, or optimized builds, you can
+run the following (via ``-c`` ``fastbuild``/``dbg``/``opt``, respectively):
+
+.. code-block:: shell
+
+ bazel build -c fastbuild //:ray_pkg
+
+This will rebuild Ray with the appropriate options (which may take a while).
+If you need to build all targets, you can use ``"//:*"`` instead of
+``//:ray_pkg``.
+
+To make this change permanent, you can add an option such as the following
+line to your user-level ``~/.bazelrc`` file (not to be confused with the
+workspace-level ``.bazelrc`` file):
+
+.. code-block:: shell
+
+ build --compilation_mode=fastbuild
+
+If you do so, remember to revert this change, unless you want it to affect
+all of your development in the future.
+
+Using ``dbg`` instead of ``fastbuild`` generates more debug information,
+which can make it easier to debug with a debugger like ``gdb``.
+
 .. _python-develop:
 
 Developing Ray (Python Only)
diff --git a/python/ray/_raylet.pxd b/python/ray/_raylet.pxd
index e69b5c452..969801655 100644
--- a/python/ray/_raylet.pxd
+++ b/python/ray/_raylet.pxd
@@ -26,6 +26,18 @@ from ray.includes.function_descriptor cimport (
     CFunctionDescriptor,
 )
 
+cdef extern from *:
+   """
+   #if __OPTIMIZE__ && __OPTIMIZE__ == 1
+   #undef __OPTIMIZE__
+   int __OPTIMIZE__ = 1;
+   #define __OPTIMIZE__ 1
+   #else
+   int __OPTIMIZE__ = 0;
+   #endif
+   """
+   int __OPTIMIZE__
+
 cdef extern from "Python.h":
     # Note(simon): This is used to configure asyncio actor stack size.
     # Cython made PyThreadState an opaque types. Saying that if the user wants
diff --git a/python/ray/_raylet.pyx b/python/ray/_raylet.pyx
index 48df281cc..d3a65bd0b 100644
--- a/python/ray/_raylet.pyx
+++ b/python/ray/_raylet.pyx
@@ -109,6 +109,8 @@ include "includes/serialization.pxi"
 include "includes/libcoreworker.pxi"
 include "includes/global_state_accessor.pxi"
 
+# Expose GCC & Clang macro to report whether C++ optimizations were enabled during compilation.
+OPTIMIZED = __OPTIMIZE__
 
 logger = logging.getLogger(__name__)
 
diff --git a/python/ray/ray_perf.py b/python/ray/ray_perf.py
index 55c3c100c..789ac5b6a 100644
--- a/python/ray/ray_perf.py
+++ b/python/ray/ray_perf.py
@@ -1,12 +1,15 @@
 """This is the script for `ray microbenchmark`."""
 
 import asyncio
+import logging
 import os
 import time
 import numpy as np
 import multiprocessing
 import ray
 
+logger = logging.getLogger(__name__)
+
 # Only run tests matching this filter pattern.
 filter_pattern = os.environ.get("TESTS_TO_RUN", "")
 
@@ -89,7 +92,21 @@ def timeit(name, fn, multiplier=1):
           round(np.std(stats), 2))
 
 
+def check_optimized_build():
+    if not ray._raylet.OPTIMIZED:
+        msg = ("WARNING: Unoptimized build! "
+               "To benchmark an optimized build, try:\n"
+               "\tbazel build -c opt //:ray_pkg\n"
+               "You can also make this permanent by adding\n"
+               "\tbuild --compilation_mode=opt\n"
+               "to your user-wide ~/.bazelrc file. "
+               "(Do not add this to the project-level .bazelrc file.)")
+        logger.warning(msg)
+
+
 def main():
+    check_optimized_build()
+
     print("Tip: set TESTS_TO_RUN='pattern' to run a subset of benchmarks")
     ray.init()