diff --git a/.circleci/config.yml b/.circleci/config.yml
index 064c7036..808f8c42 100644
--- a/.circleci/config.yml
+++ b/.circleci/config.yml
@@ -54,7 +54,7 @@ jobs:
       - *run-tests
       - *upload-coverage
     environment:
-      YCMD_PYTHON_VERSION: 3.3
+      YCMD_PYTHON_VERSION: 3.4
 workflows:
   version: 2
   build:
diff --git a/.circleci/install_dependencies.sh b/.circleci/install_dependencies.sh
index c25c2527..75172376 100755
--- a/.circleci/install_dependencies.sh
+++ b/.circleci/install_dependencies.sh
@@ -49,9 +49,9 @@ eval "$(pyenv init -)"
 if [ "${YCMD_PYTHON_VERSION}" == "2.7" ]; then
   # We need a recent enough version of Python 2.7 on macOS or an error occurs
   # when installing the psutil dependency for our tests.
-  PYENV_VERSION="2.7.8"
+  PYENV_VERSION="2.7.14"
 else
-  PYENV_VERSION="3.3.6"
+  PYENV_VERSION="3.4.7"
 fi
 
 # In order to work with ycmd, python *must* be built as a shared library. The
diff --git a/.travis.yml b/.travis.yml
index 290e323b..d34749c6 100644
--- a/.travis.yml
+++ b/.travis.yml
@@ -14,9 +14,8 @@ env:
     - YCM_CORES=3
     - COVERAGE=true
   matrix:
-    - YCM_PYTHON_VERSION=2.6
     - YCM_PYTHON_VERSION=2.7
-    - YCM_PYTHON_VERSION=3.3
+    - YCM_PYTHON_VERSION=3.4
 addons:
   apt:
     sources:
diff --git a/README.md b/README.md
index 46f8a3f8..9744f6c2 100644
--- a/README.md
+++ b/README.md
@@ -2607,7 +2607,7 @@ let g:ycm_disable_for_files_larger_than_kb = 1000
 This option specifies the Python interpreter to use to run the [jedi][]
 completion library.  Specify the Python interpreter to use to get completions.
 By default the Python under which [ycmd][] runs is used ([ycmd][] runs on
-Python 2.6, 2.7 or 3.3+).
+Python 2.7 or 3.4+).
 
 Default: `''`
 
diff --git a/ci/travis/travis_install.sh b/ci/travis/travis_install.sh
index 2014c5ea..3283c3d2 100644
--- a/ci/travis/travis_install.sh
+++ b/ci/travis/travis_install.sh
@@ -33,19 +33,17 @@ if [ ! -d "${PYENV_ROOT}/.git" ]; then
 fi
 pushd ${PYENV_ROOT}
 git fetch --tags
-git checkout v1.0.8
+git checkout v1.2.1
 popd
 
 export PATH="${PYENV_ROOT}/bin:${PATH}"
 
 eval "$(pyenv init -)"
 
-if [ "${YCM_PYTHON_VERSION}" == "2.6" ]; then
-  PYENV_VERSION="2.6.6"
-elif [ "${YCM_PYTHON_VERSION}" == "2.7" ]; then
-  PYENV_VERSION="2.7.6"
+if [ "${YCM_PYTHON_VERSION}" == "2.7" ]; then
+  PYENV_VERSION="2.7.14"
 else
-  PYENV_VERSION="3.3.6"
+  PYENV_VERSION="3.4.7"
 fi
 
 # In order to work with ycmd, python *must* be built as a shared library. This
diff --git a/doc/youcompleteme.txt b/doc/youcompleteme.txt
index 5e42e920..38fe7a2b 100644
--- a/doc/youcompleteme.txt
+++ b/doc/youcompleteme.txt
@@ -2848,7 +2848,7 @@ The *g:ycm_python_binary_path* option
 This option specifies the Python interpreter to use to run the jedi [12]
 completion library. Specify the Python interpreter to use to get completions.
 By default the Python under which ycmd [45] runs is used (ycmd [45] runs on
-Python 2.6, 2.7 or 3.3+).
+Python 2.7 or 3.4+).
 
 Default: "''"
 >
diff --git a/plugin/youcompleteme.vim b/plugin/youcompleteme.vim
index 434f2ef3..72c2c2c5 100644
--- a/plugin/youcompleteme.vim
+++ b/plugin/youcompleteme.vim
@@ -57,7 +57,7 @@ elseif !has( 'timers' )
 elseif !has( 'python' ) && !has( 'python3' )
   echohl WarningMsg |
         \ echomsg "YouCompleteMe unavailable: requires Vim compiled with " .
-        \ "Python (2.6+ or 3.3+) support." |
+        \ "Python (2.7 or 3.4+) support." |
         \ echohl None
   call s:restore_cpo()
   finish
diff --git a/python/test_requirements.txt b/python/test_requirements.txt
index 8961b2dc..82d6b670 100644
--- a/python/test_requirements.txt
+++ b/python/test_requirements.txt
@@ -1,6 +1,4 @@
-# Flake8 3.x dropped support of Python 2.6 and 3.3
-flake8     <  3.0.0; python_version == '2.6' or python_version == '3.3'
-flake8     >= 3.0.0; python_version == '2.7' or python_version >  '3.3'
+flake8     >= 3.0.0
 mock       >= 1.0.1
 nose       >= 1.3.7
 PyHamcrest >= 1.8.0
diff --git a/python/ycm/paths.py b/python/ycm/paths.py
index 1b9009f6..a135e3a6 100644
--- a/python/ycm/paths.py
+++ b/python/ycm/paths.py
@@ -51,7 +51,7 @@ def PathToPythonInterpreter():
       return python_interpreter
 
     raise RuntimeError( "Path in 'g:ycm_server_python_interpreter' option "
-                        "does not point to a valid Python 2.6+ or 3.3+." )
+                        "does not point to a valid Python 2.7 or 3.4+." )
 
   python_interpreter = _PathToPythonUsedDuringBuild()
   if python_interpreter and utils.GetExecutable( python_interpreter ):
@@ -77,7 +77,7 @@ def PathToPythonInterpreter():
   if python_interpreter:
     return python_interpreter
 
-  raise RuntimeError( "Cannot find Python 2.6+ or 3.3+. "
+  raise RuntimeError( "Cannot find Python 2.7 or 3.4+. "
                       "Set the 'g:ycm_server_python_interpreter' option "
                       "to a Python interpreter path." )
 
@@ -94,7 +94,7 @@ def _PathToPythonUsedDuringBuild():
 
 
 def _EndsWithPython( path ):
-  """Check if given path ends with a python 2.6+ or 3.3+ name."""
+  """Check if given path ends with a python 2.7 or 3.4+ name."""
   return path and PYTHON_BINARY_REGEX.search( path ) is not None
 
 
diff --git a/python/ycm/tests/paths_test.py b/python/ycm/tests/paths_test.py
index e50572bd..34967f4f 100644
--- a/python/ycm/tests/paths_test.py
+++ b/python/ycm/tests/paths_test.py
@@ -43,9 +43,9 @@ def EndsWithPython_Python2Paths_test():
   python_paths = [
     'python',
     'python2',
-    '/usr/bin/python2.6',
+    '/usr/bin/python2.7',
     '/home/user/.pyenv/shims/python2.7',
-    r'C:\Python26\python.exe',
+    r'C:\Python27\python.exe',
     '/Contents/MacOS/Python'
   ]
 
@@ -56,9 +56,9 @@ def EndsWithPython_Python2Paths_test():
 def EndsWithPython_Python3Paths_test():
   python_paths = [
     'python3',
-    '/usr/bin/python3.3',
-    '/home/user/.pyenv/shims/python3.3',
-    r'C:\Python33\python.exe'
+    '/usr/bin/python3.4',
+    '/home/user/.pyenv/shims/python3.4',
+    r'C:\Python34\python.exe'
   ]
 
   for path in python_paths:
diff --git a/python/ycm/tests/youcompleteme_test.py b/python/ycm/tests/youcompleteme_test.py
index a908870b..9f80f488 100644
--- a/python/ycm/tests/youcompleteme_test.py
+++ b/python/ycm/tests/youcompleteme_test.py
@@ -55,7 +55,7 @@ def YouCompleteMe_InvalidPythonInterpreterPath_test( post_vim_message ):
       post_vim_message.assert_called_once_with(
         "Unable to start the ycmd server. "
         "Path in 'g:ycm_server_python_interpreter' option does not point "
-        "to a valid Python 2.6+ or 3.3+. "
+        "to a valid Python 2.7 or 3.4+. "
         "Correct the error then restart the server with ':YcmRestartServer'." )
 
     post_vim_message.reset_mock()
@@ -81,7 +81,7 @@ def YouCompleteMe_NoPythonInterpreterFound_test( post_vim_message, *args ):
       ycm = YouCompleteMe( MakeUserOptions() )
       assert_that( ycm.IsServerAlive(), equal_to( False ) )
       post_vim_message.assert_called_once_with(
-        "Unable to start the ycmd server. Cannot find Python 2.6+ or 3.3+. "
+        "Unable to start the ycmd server. Cannot find Python 2.7 or 3.4+. "
         "Set the 'g:ycm_server_python_interpreter' option to a Python "
         "interpreter path. "
         "Correct the error then restart the server with ':YcmRestartServer'." )
diff --git a/run_tests.py b/run_tests.py
index d07f708b..618b6302 100755
--- a/run_tests.py
+++ b/run_tests.py
@@ -38,10 +38,7 @@ import argparse
 def RunFlake8():
   print( 'Running flake8' )
   subprocess.check_call( [
-    sys.executable,
-    # __main__ is required on Python 2.6.
-    '-m', 'flake8.__main__',
-    p.join( DIR_OF_THIS_SCRIPT, 'python' )
+    sys.executable, '-m', 'flake8', p.join( DIR_OF_THIS_SCRIPT, 'python' )
   ] )
 
 
@@ -86,9 +83,7 @@ def NoseTests( parsed_args, extra_nosetests_args ):
   else:
     nosetests_args.append( p.join( DIR_OF_THIS_SCRIPT, 'python' ) )
 
-  subprocess.check_call( [ sys.executable,
-                           # __main__ is required on Python 2.6.
-                           '-m', 'nose.__main__' ] + nosetests_args )
+  subprocess.check_call( [ sys.executable, '-m', 'nose' ] + nosetests_args )
 
 
 def Main():