diff --git a/docs/en_us/ORA2/Makefile b/docs/en_us/ORA2/Makefile
index d02280e2fd..7a4baa06c4 100644
--- a/docs/en_us/ORA2/Makefile
+++ b/docs/en_us/ORA2/Makefile
@@ -2,17 +2,17 @@
 #
 
 # You can set these variables from the command line.
-SPHINXOPTS    =
-SPHINXBUILD   = sphinx-build
-PAPER         =
-BUILDDIR      = build
+SPHINXOPTS    ?=
+SPHINXBUILD   ?= sphinx-build
+PAPER         ?=
+BUILDDIR      ?= build
 
 # User-friendly check for sphinx-build
 ifeq ($(shell which $(SPHINXBUILD) >/dev/null 2>&1; echo $$?), 1)
 $(error The '$(SPHINXBUILD)' command was not found. Make sure you have Sphinx installed, then set the SPHINXBUILD environment variable to point to the full path of the '$(SPHINXBUILD)' executable. Alternatively you can add the directory with the executable to your PATH. If you don't have Sphinx installed, grab it from http://sphinx-doc.org/)
 endif
 
-Q_FLAG        = 
+Q_FLAG        =
 
 ifeq ($(quiet), true)
 Q_FLAG = -Q
diff --git a/docs/en_us/course_authors/Makefile b/docs/en_us/course_authors/Makefile
index d02280e2fd..7a4baa06c4 100644
--- a/docs/en_us/course_authors/Makefile
+++ b/docs/en_us/course_authors/Makefile
@@ -2,17 +2,17 @@
 #
 
 # You can set these variables from the command line.
-SPHINXOPTS    =
-SPHINXBUILD   = sphinx-build
-PAPER         =
-BUILDDIR      = build
+SPHINXOPTS    ?=
+SPHINXBUILD   ?= sphinx-build
+PAPER         ?=
+BUILDDIR      ?= build
 
 # User-friendly check for sphinx-build
 ifeq ($(shell which $(SPHINXBUILD) >/dev/null 2>&1; echo $$?), 1)
 $(error The '$(SPHINXBUILD)' command was not found. Make sure you have Sphinx installed, then set the SPHINXBUILD environment variable to point to the full path of the '$(SPHINXBUILD)' executable. Alternatively you can add the directory with the executable to your PATH. If you don't have Sphinx installed, grab it from http://sphinx-doc.org/)
 endif
 
-Q_FLAG        = 
+Q_FLAG        =
 
 ifeq ($(quiet), true)
 Q_FLAG = -Q
diff --git a/docs/en_us/data/Makefile b/docs/en_us/data/Makefile
index 2096b14f91..7a930576ed 100644
--- a/docs/en_us/data/Makefile
+++ b/docs/en_us/data/Makefile
@@ -2,17 +2,17 @@
 #
 
 # You can set these variables from the command line.
-SPHINXOPTS    =
-SPHINXBUILD   = sphinx-build
-PAPER         =
-BUILDDIR      = build
+SPHINXOPTS    ?=
+SPHINXBUILD   ?= sphinx-build
+PAPER         ?=
+BUILDDIR      ?= build
 
 # User-friendly check for sphinx-build
 ifeq ($(shell which $(SPHINXBUILD) >/dev/null 2>&1; echo $$?), 1)
 $(error The '$(SPHINXBUILD)' command was not found. Make sure you have Sphinx installed, then set the SPHINXBUILD environment variable to point to the full path of the '$(SPHINXBUILD)' executable. Alternatively you can add the directory with the executable to your PATH. If you don't have Sphinx installed, grab it from http://sphinx-doc.org/)
 endif
 
-Q_FLAG        = 
+Q_FLAG        =
 
 ifeq ($(quiet), true)
 Q_FLAG = -Q
diff --git a/docs/en_us/developers/Makefile b/docs/en_us/developers/Makefile
index a43b3b449f..58e5370a97 100644
--- a/docs/en_us/developers/Makefile
+++ b/docs/en_us/developers/Makefile
@@ -2,10 +2,10 @@
 #
 
 # You can set these variables from the command line.
-SPHINXOPTS    =
-SPHINXBUILD   = sphinx-build
-PAPER         =
-BUILDDIR      = build
+SPHINXOPTS    ?=
+SPHINXBUILD   ?= sphinx-build
+PAPER         ?=
+BUILDDIR      ?= build
 
 # User-friendly check for sphinx-build
 ifeq ($(shell which $(SPHINXBUILD) >/dev/null 2>&1; echo $$?), 1)
diff --git a/docs/en_us/install_operations/Makefile b/docs/en_us/install_operations/Makefile
index d02280e2fd..7a4baa06c4 100644
--- a/docs/en_us/install_operations/Makefile
+++ b/docs/en_us/install_operations/Makefile
@@ -2,17 +2,17 @@
 #
 
 # You can set these variables from the command line.
-SPHINXOPTS    =
-SPHINXBUILD   = sphinx-build
-PAPER         =
-BUILDDIR      = build
+SPHINXOPTS    ?=
+SPHINXBUILD   ?= sphinx-build
+PAPER         ?=
+BUILDDIR      ?= build
 
 # User-friendly check for sphinx-build
 ifeq ($(shell which $(SPHINXBUILD) >/dev/null 2>&1; echo $$?), 1)
 $(error The '$(SPHINXBUILD)' command was not found. Make sure you have Sphinx installed, then set the SPHINXBUILD environment variable to point to the full path of the '$(SPHINXBUILD)' executable. Alternatively you can add the directory with the executable to your PATH. If you don't have Sphinx installed, grab it from http://sphinx-doc.org/)
 endif
 
-Q_FLAG        = 
+Q_FLAG        =
 
 ifeq ($(quiet), true)
 Q_FLAG = -Q
diff --git a/docs/en_us/release_notes/Makefile b/docs/en_us/release_notes/Makefile
index d02280e2fd..7a4baa06c4 100644
--- a/docs/en_us/release_notes/Makefile
+++ b/docs/en_us/release_notes/Makefile
@@ -2,17 +2,17 @@
 #
 
 # You can set these variables from the command line.
-SPHINXOPTS    =
-SPHINXBUILD   = sphinx-build
-PAPER         =
-BUILDDIR      = build
+SPHINXOPTS    ?=
+SPHINXBUILD   ?= sphinx-build
+PAPER         ?=
+BUILDDIR      ?= build
 
 # User-friendly check for sphinx-build
 ifeq ($(shell which $(SPHINXBUILD) >/dev/null 2>&1; echo $$?), 1)
 $(error The '$(SPHINXBUILD)' command was not found. Make sure you have Sphinx installed, then set the SPHINXBUILD environment variable to point to the full path of the '$(SPHINXBUILD)' executable. Alternatively you can add the directory with the executable to your PATH. If you don't have Sphinx installed, grab it from http://sphinx-doc.org/)
 endif
 
-Q_FLAG        = 
+Q_FLAG        =
 
 ifeq ($(quiet), true)
 Q_FLAG = -Q