diff --git a/.gitignore b/.gitignore
index 0238a4ab78e..218ac5e8e9b 100644
--- a/.gitignore
+++ b/.gitignore
@@ -85,3 +85,5 @@ buckifier/*.pyc
 buckifier/__pycache__
 
 compile_commands.json
+clang-format-diff.py
+.py3/
diff --git a/Makefile b/Makefile
index 3141c59b449..51569ffc62b 100644
--- a/Makefile
+++ b/Makefile
@@ -8,7 +8,9 @@
 
 BASH_EXISTS := $(shell which bash)
 SHELL := $(shell which bash)
-PYTHON?=$(shell which python)
+# Default to python3. Some distros like CentOS 8 do not have `python`.
+PYTHON?=$(shell which python3 || which python || echo python3)
+export PYTHON
 
 CLEAN_FILES = # deliberately empty, so we can append below.
 CFLAGS += ${EXTRA_CFLAGS}
diff --git a/TARGETS b/TARGETS
index 5df9ae0e905..6a68b3c693f 100644
--- a/TARGETS
+++ b/TARGETS
@@ -1,4 +1,4 @@
-# This file @generated by `python buckifier/buckify_rocksdb.py`
+# This file @generated by `python3 buckifier/buckify_rocksdb.py`
 # --> DO NOT EDIT MANUALLY <--
 # This file is a Facebook-specific integration for buck builds, so can
 # only be validated by Facebook employees.
diff --git a/buckifier/buckify_rocksdb.py b/buckifier/buckify_rocksdb.py
index 6c13f6ebfad..870505b53aa 100644
--- a/buckifier/buckify_rocksdb.py
+++ b/buckifier/buckify_rocksdb.py
@@ -20,10 +20,10 @@
 # User can pass extra dependencies as a JSON object via command line, and this
 # script can include these dependencies in the generate TARGETS file.
 # Usage:
-# $python buckifier/buckify_rocksdb.py
+# $python3 buckifier/buckify_rocksdb.py
 # (This generates a TARGET file without user-specified dependency for unit
 # tests.)
-# $python buckifier/buckify_rocksdb.py \
+# $python3 buckifier/buckify_rocksdb.py \
 #        '{"fake": { \
 #                      "extra_deps": [":test_dep", "//fakes/module:mock1"],  \
 #                      "extra_compiler_flags": ["-DROCKSDB_LITE", "-Os"], \
diff --git a/buckifier/check_buck_targets.sh b/buckifier/check_buck_targets.sh
index ccf77f91d77..66c83c52f37 100755
--- a/buckifier/check_buck_targets.sh
+++ b/buckifier/check_buck_targets.sh
@@ -15,7 +15,7 @@ echo Backup original TARGETS file.
 
 cp TARGETS TARGETS.bkp
 
-python buckifier/buckify_rocksdb.py
+${PYTHON:-python3} buckifier/buckify_rocksdb.py
 
 TGT_DIFF=`git diff TARGETS | head -n 1`
 
@@ -24,9 +24,9 @@ then
   mv TARGETS.bkp TARGETS
   exit 0
 else
-  echo "Please run 'python buckifier/buckify_rocksdb.py' to update TARGETS file."
+  echo "Please run '${PYTHON:-python3} buckifier/buckify_rocksdb.py' to update TARGETS file."
   echo "Do not manually update TARGETS file."
-  python --version
+  ${PYTHON:-python3} --version
   mv TARGETS.bkp TARGETS
   exit 1
 fi
diff --git a/buckifier/targets_cfg.py b/buckifier/targets_cfg.py
index 62ef6f6c74c..f4e2973bf7d 100644
--- a/buckifier/targets_cfg.py
+++ b/buckifier/targets_cfg.py
@@ -5,7 +5,7 @@
 from __future__ import unicode_literals
 
 rocksdb_target_header_template = \
-    """# This file \100generated by `python buckifier/buckify_rocksdb.py`
+    """# This file \100generated by `python3 buckifier/buckify_rocksdb.py`
 # --> DO NOT EDIT MANUALLY <--
 # This file is a Facebook-specific integration for buck builds, so can
 # only be validated by Facebook employees.
diff --git a/build_tools/format-diff.sh b/build_tools/format-diff.sh
index 70da9a5782f..386885b578e 100755
--- a/build_tools/format-diff.sh
+++ b/build_tools/format-diff.sh
@@ -26,53 +26,77 @@ while getopts ':ch' OPTION; do
   esac
 done
 
-if [ -z $CLANG_FORMAT_DIFF ]
-then
-CLANG_FORMAT_DIFF="clang-format-diff.py"
-fi
+REPO_ROOT="$(git rev-parse --show-toplevel)"
 
-# Check clang-format-diff.py
-if ! which $CLANG_FORMAT_DIFF &> /dev/null
-then
-  if [ ! -f ./clang-format-diff.py ]
-  then
-    echo "You didn't have clang-format-diff.py and/or clang-format available in your computer!"
-    echo "You can download clang-format-diff.py by running: "
-    echo "    curl --location http://goo.gl/iUW1u2 -o ${CLANG_FORMAT_DIFF}"
-    echo "You can download clang-format by running:"
-    echo "    brew install clang-format"
-    echo "  Or"
-    echo "    apt install clang-format"
-    echo "  This might work too:"
-    echo "    yum install git-clang-format"
-    echo "Then, move both files (i.e. ${CLANG_FORMAT_DIFF} and clang-format) to some directory within PATH=${PATH}"
-    echo "and make sure ${CLANG_FORMAT_DIFF} is executable."
+if [ "$CLANG_FORMAT_DIFF" ]; then
+  echo "Note: CLANG_FORMAT_DIFF='$CLANG_FORMAT_DIFF'"
+  # Dry run to confirm dependencies like argparse
+  if $CLANG_FORMAT_DIFF --help >/dev/null < /dev/null; then
+    true #Good
+  else
     exit 128
+  fi
+else
+  # First try directly executing the possibilities
+  if clang-format-diff.py --help &> /dev/null < /dev/null; then
+    CLANG_FORMAT_DIFF=clang-format-diff.py
+  elif $REPO_ROOT/clang-format-diff.py --help &> /dev/null < /dev/null; then
+    CLANG_FORMAT_DIFF=$REPO_ROOT/clang-format-diff.py
   else
-    if [ -x ./clang-format-diff.py ]
-    then
-      PATH=$PATH:.
+    # This probably means we need to directly invoke the interpreter.
+    # But first find clang-format-diff.py
+    if [ -f "$REPO_ROOT/clang-format-diff.py" ]; then
+      CFD_PATH="$REPO_ROOT/clang-format-diff.py"
+    elif which clang-format-diff.py &> /dev/null; then
+      CFD_PATH="$(which clang-format-diff.py)"
+    else
+      echo "You didn't have clang-format-diff.py and/or clang-format available in your computer!"
+      echo "You can download clang-format-diff.py by running: "
+      echo "    curl --location http://goo.gl/iUW1u2 -o ${CLANG_FORMAT_DIFF}"
+      echo "You can download clang-format by running:"
+      echo "    brew install clang-format"
+      echo "  Or"
+      echo "    apt install clang-format"
+      echo "  This might work too:"
+      echo "    yum install git-clang-format"
+      echo "Then, move both files (i.e. ${CLANG_FORMAT_DIFF} and clang-format) to some directory within PATH=${PATH}"
+      echo "and make sure ${CLANG_FORMAT_DIFF} is executable."
+      exit 128
+    fi
+    # Check argparse pre-req on interpreter, or it will fail
+    if echo import argparse | ${PYTHON:-python3}; then
+      true # Good
+    else
+      echo "To run clang-format-diff.py, we'll need the library "argparse" to be"
+      echo "installed. You can try either of the follow ways to install it:"
+      echo "  1. Manually download argparse: https://pypi.python.org/pypi/argparse"
+      echo "  2. easy_install argparse (if you have easy_install)"
+      echo "  3. pip install argparse (if you have pip)"
+      exit 129
+    fi
+    # Unfortunately, some machines have a Python2 clang-format-diff.py
+    # installed but only a Python3 interpreter installed. Rather than trying
+    # different Python versions that might be installed, we can try migrating
+    # the code to Python3 if it looks like Python2
+    if grep -q "print '" "$CFD_PATH" && \
+       ${PYTHON:-python3} --version | grep -q 'ython 3'; then
+      if [ ! -f "$REPO_ROOT/.py3/clang-format-diff.py" ]; then
+        echo "Migrating $CFD_PATH to Python3 in a hidden file"
+        mkdir -p "$REPO_ROOT/.py3"
+        ${PYTHON:-python3} -m lib2to3 -w -n -o "$REPO_ROOT/.py3" "$CFD_PATH" > /dev/null || exit 128
+      fi
+      CFD_PATH="$REPO_ROOT/.py3/clang-format-diff.py"
+    fi
+    CLANG_FORMAT_DIFF="${PYTHON:-python3} $CFD_PATH"
+    # This had better work after all those checks
+    if $CLANG_FORMAT_DIFF --help >/dev/null < /dev/null; then
+      true #Good
     else
-      CLANG_FORMAT_DIFF="python ./clang-format-diff.py"
+      exit 128
     fi
   fi
 fi
 
-# Check argparse, a library that clang-format-diff.py requires.
-python 2>/dev/null << EOF
-import argparse
-EOF
-
-if [ "$?" != 0 ]
-then
-  echo "To run clang-format-diff.py, we'll need the library "argparse" to be"
-  echo "installed. You can try either of the follow ways to install it:"
-  echo "  1. Manually download argparse: https://pypi.python.org/pypi/argparse"
-  echo "  2. easy_install argparse (if you have easy_install)"
-  echo "  3. pip install argparse (if you have pip)"
-  exit 129
-fi
-
 # TODO(kailiu) following work is not complete since we still need to figure
 # out how to add the modified files done pre-commit hook to git's commit index.
 #
diff --git a/tools/check_all_python.py b/tools/check_all_python.py
old mode 100644
new mode 100755
index 17fe95eab96..b4a41c10e56
--- a/tools/check_all_python.py
+++ b/tools/check_all_python.py
@@ -1,4 +1,4 @@
-#!/usr/bin/env python2
+#!/usr/bin/env python3
 # Copyright (c) Facebook, Inc. and its affiliates. All Rights Reserved.
 import glob
 
diff --git a/tools/db_crashtest.py b/tools/db_crashtest.py
index 630b96b041c..25d38c4f28c 100644
--- a/tools/db_crashtest.py
+++ b/tools/db_crashtest.py
@@ -1,4 +1,4 @@
-#!/usr/bin/env python
+#!/usr/bin/env python3
 # Copyright (c) Facebook, Inc. and its affiliates. All Rights Reserved.
 from __future__ import absolute_import, division, print_function, unicode_literals
 
diff --git a/tools/ldb_test.py b/tools/ldb_test.py
index 9773b85f81f..46edfa4e572 100644
--- a/tools/ldb_test.py
+++ b/tools/ldb_test.py
@@ -1,4 +1,4 @@
-#!/usr/bin/env python
+#!/usr/bin/env python3
 # Copyright (c) Facebook, Inc. and its affiliates. All Rights Reserved.
 from __future__ import absolute_import, division, print_function, unicode_literals
 
diff --git a/tools/write_stress_runner.py b/tools/write_stress_runner.py
index 51daa24e837..962515dfb50 100644
--- a/tools/write_stress_runner.py
+++ b/tools/write_stress_runner.py
@@ -1,4 +1,4 @@
-#!/usr/bin/env python
+#!/usr/bin/env python3
 # Copyright (c) Facebook, Inc. and its affiliates. All Rights Reserved.
 from __future__ import absolute_import, division, print_function, unicode_literals