diff --git a/.eslintrc b/.eslintrc
index 025abf510e442..81f9691a139cb 100644
--- a/.eslintrc
+++ b/.eslintrc
@@ -27,6 +27,7 @@
   },
   "rules": {
     "no-console": "off",
+    "no-inner-declarations": "off",
     "valid-jsdoc": "off",
     "require-jsdoc": "off",
     "quotes": ["error", "backtick"],
diff --git a/docs/docs/plugins.md b/docs/docs/plugins.md
index d5ed554e48071..b1b420d0cec82 100644
--- a/docs/docs/plugins.md
+++ b/docs/docs/plugins.md
@@ -77,7 +77,7 @@ root.
 ## Official plugins
 
 * [gatsby-plugin-catch-links](/packages/gatsby-plugin-catch-links/)
-* [gatsby-plugin-client-only-paths](/packages/gatsby-plugin-client-only-paths/)
+* [gatsby-plugin-create-client-paths](/packages/gatsby-plugin-create-client-paths/)
 * [gatsby-plugin-coffeescript](/packages/gatsby-plugin-coffeescript/)
 * [gatsby-plugin-feed](/packages/gatsby-plugin-feed/)
 * [gatsby-plugin-glamor](/packages/gatsby-plugin-glamor/)
diff --git a/packages/gatsby-remark-autolink-headers/package.json b/packages/gatsby-remark-autolink-headers/package.json
index b7a49b9ee9d87..d970d7db3fb1e 100644
--- a/packages/gatsby-remark-autolink-headers/package.json
+++ b/packages/gatsby-remark-autolink-headers/package.json
@@ -1,7 +1,7 @@
 {
   "name": "gatsby-remark-autolink-headers",
   "description": "Gatsby plugin to autolink headers in markdown processed by Remark",
-  "version": "1.4.10",
+  "version": "1.4.11",
   "author": "Kyle Mathews <mathews.kyle@gmail.com>",
   "dependencies": {
     "babel-runtime": "^6.26.0",
diff --git a/packages/gatsby-remark-autolink-headers/src/gatsby-browser.js b/packages/gatsby-remark-autolink-headers/src/gatsby-browser.js
index 223671f5edb1d..0d82719482752 100644
--- a/packages/gatsby-remark-autolink-headers/src/gatsby-browser.js
+++ b/packages/gatsby-remark-autolink-headers/src/gatsby-browser.js
@@ -1,7 +1,7 @@
 const scrollToHash = offsetY => {
-  // Make sure React has had a change to flush to DOM first.
+  // Make sure React has had a chance to flush to DOM first.
   setTimeout(() => {
-    const hash = window.location.hash.replace(`#`, ``)
+    const hash = window.decodeURI(window.location.hash.replace(`#`, ``))
     if (hash !== ``) {
       const element = document.getElementById(hash)
       if (element) {
diff --git a/packages/gatsby-remark-autolink-headers/src/gatsby-ssr.js b/packages/gatsby-remark-autolink-headers/src/gatsby-ssr.js
index 6ebd10c1e9d02..11648c1fb0e39 100644
--- a/packages/gatsby-remark-autolink-headers/src/gatsby-ssr.js
+++ b/packages/gatsby-remark-autolink-headers/src/gatsby-ssr.js
@@ -32,7 +32,7 @@ exports.onRenderBody = ({ setHeadComponents }, pluginOptions) => {
 
   const script = `
     document.addEventListener("DOMContentLoaded", function(event) {
-      var hash = location.hash.replace('#', '')
+      var hash = window.decodeURI(location.hash.replace('#', ''))
       if (hash !== '') {
         var element = document.getElementById(hash)
         if (element) {
diff --git a/packages/gatsby-remark-custom-blocks/.gitignore b/packages/gatsby-remark-custom-blocks/.gitignore
new file mode 100644
index 0000000000000..de4d1f007dd19
--- /dev/null
+++ b/packages/gatsby-remark-custom-blocks/.gitignore
@@ -0,0 +1,2 @@
+dist
+node_modules
diff --git a/packages/gatsby-remark-custom-blocks/.npmignore b/packages/gatsby-remark-custom-blocks/.npmignore
new file mode 100644
index 0000000000000..e771d2c9fa299
--- /dev/null
+++ b/packages/gatsby-remark-custom-blocks/.npmignore
@@ -0,0 +1,34 @@
+# Logs
+logs
+*.log
+
+# Runtime data
+pids
+*.pid
+*.seed
+
+# Directory for instrumented libs generated by jscoverage/JSCover
+lib-cov
+
+# Coverage directory used by tools like istanbul
+coverage
+
+# Grunt intermediate storage (http://gruntjs.com/creating-plugins#storing-task-files)
+.grunt
+
+# node-waf configuration
+.lock-wscript
+
+# Compiled binary addons (http://nodejs.org/api/addons.html)
+build/Release
+
+# Dependency directory
+# https://www.npmjs.org/doc/misc/npm-faq.html#should-i-check-my-node_modules-folder-into-git
+node_modules
+*.un~
+yarn.lock
+src
+flow-typed
+coverage
+decls
+examples
diff --git a/packages/gatsby-remark-custom-blocks/README.md b/packages/gatsby-remark-custom-blocks/README.md
new file mode 100644
index 0000000000000..a8b81f55288f4
--- /dev/null
+++ b/packages/gatsby-remark-custom-blocks/README.md
@@ -0,0 +1,31 @@
+# gatsby-remark-custom-blocks
+
+Adds custom blocks to `MarkdownRemark` using [remark-custom-blocks](https://github.com/zestedesavoir/zmarkdown/tree/master/packages/remark-custom-blocks).
+
+## Install
+
+`npm install --save gatsby-remark-custom-blocks`
+
+## How to use
+
+```javascript
+// In your gatsby-config.js
+plugins: [
+  {
+    resolve: `gatsby-transformer-remark`,
+    options: {
+      plugins: [
+        {
+          resolve: "gatsby-remark-custom-blocks",
+          options: {
+            blocks: {
+              danger: "custom-block-danger",
+              info: "custom-block-info",
+            },
+          },
+        },
+      ],
+    },
+  },
+];
+```
diff --git a/packages/gatsby-remark-custom-blocks/package.json b/packages/gatsby-remark-custom-blocks/package.json
new file mode 100644
index 0000000000000..f9a36801cf4c1
--- /dev/null
+++ b/packages/gatsby-remark-custom-blocks/package.json
@@ -0,0 +1,33 @@
+{
+  "name": "gatsby-remark-custom-blocks",
+  "version": "1.0.1",
+  "description": "Gatsby remark plugin for adding custom blocks in markdown",
+  "main": "dist/index.js",
+  "scripts": {
+    "prebuild": "rimraf dist",
+    "build": "yarn prebuild && babel --out-dir dist --ignore __tests__ src",
+    "prepublish": "yarn build"
+  },
+  "repository": "https://github.com/AlahmadiQ8/gatsby-remark-custom-blocks",
+  "keywords": [
+    "gatsby",
+    "gatsby-plugin",
+    "markdown",
+    "remark"
+  ],
+  "author": "Mohammad Asad Mohammad <m91.alahmadi@gmail.com>",
+  "license": "MIT",
+  "private": false,
+  "files": [
+    "dist",
+    "README.md"
+  ],
+  "devDependencies": {
+    "babel-cli": "^6.26.0",
+    "rimraf": "^2.6.2",
+    "unist-util-find": "^1.0.1"
+  },
+  "dependencies": {
+    "remark-custom-blocks": "^1.0.6"
+  }
+}
diff --git a/packages/gatsby-remark-custom-blocks/src/__tests__/index.js b/packages/gatsby-remark-custom-blocks/src/__tests__/index.js
new file mode 100644
index 0000000000000..cc3b2e3efdf37
--- /dev/null
+++ b/packages/gatsby-remark-custom-blocks/src/__tests__/index.js
@@ -0,0 +1,30 @@
+const Remark = require(`remark`)
+const find = require(`unist-util-find`)
+const plugin = require(`../index`)
+
+describe(`gatsby-remark-custom-blocks`, () => {
+  let remark
+
+  beforeEach(() => {
+    remark = new Remark()
+  })
+
+  it(`errors if missing required plugin options`, () => {
+    expect(plugin.setParserPlugins).toThrow(`missing required "blocks" option`)
+  })
+
+  it(`creates nodes of blocks given in options`, () => {
+    const parserPlugins = plugin.setParserPlugins({
+      blocks: { someType: `test`, anotherType: `another` },
+    })
+    const [parser, options] = parserPlugins[0]
+    remark.use(parser, options)
+    const markdownAST = remark.parse(`
+[[someType]]
+| content
+[[anotherType]]
+| content`)
+    expect(find(markdownAST, { type: `someTypeCustomBlock` })).toBeTruthy()
+    expect(find(markdownAST, { type: `anotherTypeCustomBlock` })).toBeTruthy()
+  })
+})
diff --git a/packages/gatsby-remark-custom-blocks/src/index.js b/packages/gatsby-remark-custom-blocks/src/index.js
new file mode 100644
index 0000000000000..e901d5c9a84c7
--- /dev/null
+++ b/packages/gatsby-remark-custom-blocks/src/index.js
@@ -0,0 +1,10 @@
+const isNil = require(`lodash/isNil`)
+const has = require(`lodash/has`)
+const remarkCustomBlocks = require(`remark-custom-blocks`)
+
+module.exports.setParserPlugins = options => {
+  if (isNil(options) || !has(options, `blocks`)) {
+    throw Error(`missing required "blocks" option`)
+  }
+  return [[remarkCustomBlocks, options.blocks]]
+}
diff --git a/packages/gatsby-transformer-remark/package.json b/packages/gatsby-transformer-remark/package.json
index efaf7e092c78d..6476cce6ccb93 100644
--- a/packages/gatsby-transformer-remark/package.json
+++ b/packages/gatsby-transformer-remark/package.json
@@ -1,7 +1,7 @@
 {
   "name": "gatsby-transformer-remark",
   "description": "Gatsby transformer plugin for Markdown using the Remark library and ecosystem",
-  "version": "1.7.25",
+  "version": "1.7.26",
   "author": "Kyle Mathews <mathews.kyle@gmail.com>",
   "dependencies": {
     "babel-runtime": "^6.26.0",
diff --git a/packages/gatsby-transformer-remark/src/extend-node-type.js b/packages/gatsby-transformer-remark/src/extend-node-type.js
index 97a5e191473fd..3390f36b36a6d 100644
--- a/packages/gatsby-transformer-remark/src/extend-node-type.js
+++ b/packages/gatsby-transformer-remark/src/extend-node-type.js
@@ -60,8 +60,15 @@ module.exports = (
     for (let plugin of pluginOptions.plugins) {
       const requiredPlugin = require(plugin.resolve)
       if (_.isFunction(requiredPlugin.setParserPlugins)) {
-        for (let parserPlugin of requiredPlugin.setParserPlugins()) {
-          remark = remark.use(parserPlugin)
+        for (let parserPlugin of requiredPlugin.setParserPlugins(
+          plugin.pluginOptions
+        )) {
+          if (_.isArray(parserPlugin)) {
+            const [parser, options] = parserPlugin
+            remark = remark.use(parser, options)
+          } else {
+            remark = remark.use(parserPlugin)
+          }
         }
       }
     }
diff --git a/packages/gatsby/cache-dir/__tests__/loader.js b/packages/gatsby/cache-dir/__tests__/loader.js
index dfd3c2dd5deee..f2203d0c0e5b6 100644
--- a/packages/gatsby/cache-dir/__tests__/loader.js
+++ b/packages/gatsby/cache-dir/__tests__/loader.js
@@ -2,6 +2,13 @@ import loader from "../loader.js"
 
 describe(`Loader`, () => {
   beforeEach(() => {
+    delete global.__PATH_PREFIX__
+    delete global.__PREFIX_PATHS__
+
+    // Workaround for Node 6 issue: https://github.com/facebook/jest/issues/5159
+    if (global.hasOwnProperty(`__PATH_PREFIX__`)) global.__PATH_PREFIX__ = undefined
+    if (global.hasOwnProperty(`__PREFIX_PATHS__`)) global.__PREFIX_PATHS__ = undefined
+
     loader.empty()
     loader.addPagesArray([
       {
@@ -68,3 +75,72 @@ describe(`Loader`, () => {
     expect(loader.getResources()).toMatchSnapshot()
   })
 })
+
+describe(`Loader path prefixing`, () => {
+  let pagesArray
+
+  beforeEach(() => {
+    delete global.__PATH_PREFIX__
+    delete global.__PREFIX_PATHS__
+
+    // Workaround for Node 6 issue: https://github.com/facebook/jest/issues/5159
+    if (global.hasOwnProperty(`__PATH_PREFIX__`)) global.__PATH_PREFIX__ = undefined
+    if (global.hasOwnProperty(`__PREFIX_PATHS__`)) global.__PREFIX_PATHS__ = undefined
+
+    pagesArray = [
+      {
+        path: `/about/`,
+        componentChunkName: `page-component---src-pages-test-js`,
+        jsonName: `about.json`,
+      },
+      {
+        path: `/about/me/`,
+        componentChunkName: `page-component---src-pages-test-js`,
+        jsonName: `about-me.json`,
+      },
+    ]
+
+    loader.empty()
+  })
+
+  test(`Path prefix present and enabled`, () => {
+    global.__PATH_PREFIX__ = `/foo`
+    global.__PREFIX_PATHS__ = true
+    loader.addPagesArray(pagesArray)
+    loader.enqueue(`/foo/about/`)
+    expect(loader.has(`/about/`)).toEqual(true)
+    expect(loader.has(`/foo/about/`)).toEqual(false)
+  })
+
+  test(`Path prefix present but not enabled`, () => {
+    global.__PATH_PREFIX__ = `/foo`
+    delete global.__PREFIX_PATHS__
+    loader.addPagesArray(pagesArray)
+
+    // don't enqueue prefixed paths
+    loader.enqueue(`/foo/about/`)
+    expect(loader.has(`/about/`)).toEqual(false)
+    expect(loader.has(`/foo/about/`)).toEqual(false)
+
+    // do enqueue unprefixed paths
+    loader.enqueue(`/about/`)
+    expect(loader.has(`/about/`)).toEqual(true)
+    expect(loader.has(`/foo/about/`)).toEqual(false)
+  })
+
+  test(`Path prefix missing but enabled`, () => {
+    delete global.__PATH_PREFIX__
+    global.__PREFIX_PATHS__ = true
+    loader.addPagesArray(pagesArray)
+
+    // don't enqueue prefixed paths
+    loader.enqueue(`/foo/about/`)
+    expect(loader.has(`/about/`)).toEqual(false)
+    expect(loader.has(`/foo/about/`)).toEqual(false)
+
+    // do enqueue unprefixed paths
+    loader.enqueue(`/about/`)
+    expect(loader.has(`/about/`)).toEqual(true)
+    expect(loader.has(`/foo/about/`)).toEqual(false)
+  })
+})
diff --git a/packages/gatsby/cache-dir/__tests__/strip-prefix.js b/packages/gatsby/cache-dir/__tests__/strip-prefix.js
new file mode 100644
index 0000000000000..78fc19be1d27c
--- /dev/null
+++ b/packages/gatsby/cache-dir/__tests__/strip-prefix.js
@@ -0,0 +1,23 @@
+const stripPrefix = require(`../strip-prefix`).default
+
+describe(`strip-prefix`, () => {
+  it(`strips a prefix`, () => {
+    expect(stripPrefix(`/foo/bar/`, `/foo`)).toBe(`/bar/`)
+  })
+
+  it(`strips first instance only`, () => {
+    expect(stripPrefix(`/foo/foo/bar/`, `/foo`)).toBe(`/foo/bar/`)
+  })
+
+  it(`ignores prefix appearing elsewhere in the string`, () => {
+    expect(stripPrefix(`/foo/bar/`, `bar`)).toBe(`/foo/bar/`)
+  })
+
+  it(`ignores a non-existent prefix`, () => {
+    expect(stripPrefix(`/bar`, `/foo`)).toBe(`/bar`)
+  })
+
+  it(`returns input str if no prefix is provided`, () => {
+    expect(stripPrefix(`/bar`)).toBe(`/bar`)
+  })
+})
diff --git a/packages/gatsby/cache-dir/find-page.js b/packages/gatsby/cache-dir/find-page.js
index f32c2f0ea16a4..55904b449438f 100644
--- a/packages/gatsby/cache-dir/find-page.js
+++ b/packages/gatsby/cache-dir/find-page.js
@@ -1,12 +1,14 @@
 // TODO add tests especially for handling prefixed links.
 import { matchPath } from "react-router-dom"
+import stripPrefix from "./strip-prefix"
 
 const pageCache = {}
 
 module.exports = (pages, pathPrefix = ``) => rawPathname => {
   let pathname = decodeURIComponent(rawPathname)
+
   // Remove the pathPrefix from the pathname.
-  let trimmedPathname = pathname.slice(pathPrefix.length)
+  let trimmedPathname = stripPrefix(pathname, pathPrefix)
 
   // Remove any hashfragment
   if (trimmedPathname.split(`#`).length > 1) {
diff --git a/packages/gatsby/cache-dir/loader.js b/packages/gatsby/cache-dir/loader.js
index 2659118d33889..51a8006b8cda1 100644
--- a/packages/gatsby/cache-dir/loader.js
+++ b/packages/gatsby/cache-dir/loader.js
@@ -1,6 +1,7 @@
 import React, { createElement } from "react"
 import pageFinderFactory from "./find-page"
 import emitter from "./emitter"
+import stripPrefix from "./strip-prefix"
 let findPage
 
 let syncRequires = {}
@@ -14,6 +15,7 @@ let pages = []
 // we load all resources for likely-to-be-visited paths.
 let pathArray = []
 let pathCount = {}
+let pathPrefix = ``
 let resourcesArray = []
 let resourcesCount = {}
 const preferDefault = m => (m && m.default) || m
@@ -153,12 +155,15 @@ const queue = {
     resourcesCount = {}
     resourcesArray = []
     pages = []
+    pathPrefix = ``
   },
   addPagesArray: newPages => {
     pages = newPages
-    let pathPrefix = ``
-    if (typeof __PREFIX_PATHS__ !== `undefined`) {
-      pathPrefix = __PATH_PREFIX__
+    if (
+      typeof __PREFIX_PATHS__ !== `undefined` &&
+      typeof __PATH_PREFIX__ !== `undefined`
+    ) {
+      if (__PREFIX_PATHS__ === true) pathPrefix = __PATH_PREFIX__
     }
     findPage = pageFinderFactory(newPages, pathPrefix)
   },
@@ -168,9 +173,10 @@ const queue = {
   addProdRequires: prodRequires => {
     asyncRequires = prodRequires
   },
-  dequeue: path => pathArray.pop(),
-  enqueue: path => {
+  dequeue: () => pathArray.pop(),
+  enqueue: rawPath => {
     // Check page exists.
+    const path = stripPrefix(rawPath, pathPrefix)
     if (!pages.some(p => p.path === path)) {
       return false
     }
diff --git a/packages/gatsby/cache-dir/production-app.js b/packages/gatsby/cache-dir/production-app.js
index 467d85400dd6a..613d52eeb4875 100644
--- a/packages/gatsby/cache-dir/production-app.js
+++ b/packages/gatsby/cache-dir/production-app.js
@@ -8,6 +8,7 @@ import { Router, Route, withRouter, matchPath } from "react-router-dom"
 import { ScrollContext } from "gatsby-react-router-scroll"
 import domReady from "domready"
 import history from "./history"
+window.___history = history
 import emitter from "./emitter"
 window.___emitter = emitter
 import pages from "./pages.json"
@@ -101,9 +102,11 @@ apiRunnerAsync(`onClientEntry`).then(() => {
     action: history.action,
   })
 
+  let initialAttachDone = false
   function attachToHistory(history) {
-    if (!window.___history) {
+    if (!window.___history || initialAttachDone === false) {
       window.___history = history
+      initialAttachDone = true
 
       history.listen((location, action) => {
         if (!maybeRedirect(location.pathname)) {
diff --git a/packages/gatsby/cache-dir/strip-prefix.js b/packages/gatsby/cache-dir/strip-prefix.js
new file mode 100644
index 0000000000000..f5b83ccb56c71
--- /dev/null
+++ b/packages/gatsby/cache-dir/strip-prefix.js
@@ -0,0 +1,9 @@
+/**
+ * Remove a prefix from a string. Return the input string if the given prefix
+ * isn't found.
+ */
+
+export default (str, prefix = ``) => {
+  if (str.substr(0, prefix.length) === prefix) return str.slice(prefix.length)
+  return str
+}
diff --git a/packages/gatsby/package.json b/packages/gatsby/package.json
index 30ef1d82e41d2..5511836e05d97 100644
--- a/packages/gatsby/package.json
+++ b/packages/gatsby/package.json
@@ -1,7 +1,7 @@
 {
   "name": "gatsby",
   "description": "React.js Static Site Generator",
-  "version": "1.9.147",
+  "version": "1.9.149",
   "author": "Kyle Mathews <mathews.kyle@gmail.com>",
   "bin": {
     "gatsby": "./dist/bin/gatsby.js"
diff --git a/packages/gatsby/src/commands/develop.js b/packages/gatsby/src/commands/develop.js
index 0326ccc4e6540..69786ac445ee6 100644
--- a/packages/gatsby/src/commands/develop.js
+++ b/packages/gatsby/src/commands/develop.js
@@ -96,7 +96,10 @@ async function startServer(program) {
   // Allow requests from any origin. Avoids CORS issues when using the `--host` flag.
   app.use((req, res, next) => {
     res.header(`Access-Control-Allow-Origin`, `*`)
-    res.header(`Access-Control-Allow-Headers`, `Origin, X-Requested-With, Content-Type, Accept`)
+    res.header(
+      `Access-Control-Allow-Headers`,
+      `Origin, X-Requested-With, Content-Type, Accept`
+    )
     next()
   })
 
diff --git a/yarn.lock b/yarn.lock
index c82d2767a7879..2affa1805775f 100644
--- a/yarn.lock
+++ b/yarn.lock
@@ -10416,6 +10416,12 @@ relay-runtime@1.4.1:
     fbjs "^0.8.14"
     relay-debugger-react-native-runtime "0.0.10"
 
+remark-custom-blocks@^1.0.6:
+  version "1.0.6"
+  resolved "https://registry.npmjs.org/remark-custom-blocks/-/remark-custom-blocks-1.0.6.tgz#2a756630cbfa6943ee69fa76432c59e4cd36112e"
+  dependencies:
+    space-separated-tokens "^1.1.1"
+
 remark-html@6.0.1:
   version "6.0.1"
   resolved "https://registry.yarnpkg.com/remark-html/-/remark-html-6.0.1.tgz#5094d2c71f7941fdb2ae865bac76627757ce09c1"
@@ -10883,7 +10889,7 @@ right-align@^0.1.1:
   dependencies:
     align-text "^0.1.1"
 
-rimraf@2, rimraf@^2.2.6, rimraf@^2.2.8, rimraf@^2.3.2, rimraf@^2.3.3, rimraf@^2.4.4, rimraf@^2.5.0, rimraf@^2.5.1, rimraf@^2.5.4, rimraf@^2.6.1:
+rimraf@2, rimraf@^2.2.6, rimraf@^2.2.8, rimraf@^2.3.2, rimraf@^2.3.3, rimraf@^2.4.4, rimraf@^2.5.0, rimraf@^2.5.1, rimraf@^2.5.4, rimraf@^2.6.1, rimraf@^2.6.2:
   version "2.6.2"
   resolved "https://registry.yarnpkg.com/rimraf/-/rimraf-2.6.2.tgz#2ed8150d24a16ea8651e6d6ef0f47c4158ce7a36"
   dependencies:
@@ -11614,7 +11620,7 @@ sourcemapped-stacktrace@^1.1.6:
   dependencies:
     source-map "0.5.6"
 
-space-separated-tokens@^1.0.0:
+space-separated-tokens@^1.0.0, space-separated-tokens@^1.1.1:
   version "1.1.1"
   resolved "https://registry.yarnpkg.com/space-separated-tokens/-/space-separated-tokens-1.1.1.tgz#9695b9df9e65aec1811d4c3f9ce52520bc2f7e4d"
   dependencies:
@@ -12696,7 +12702,7 @@ unist-builder@^1.0.0, unist-builder@^1.0.1:
 
 unist-util-find@^1.0.1:
   version "1.0.1"
-  resolved "https://registry.yarnpkg.com/unist-util-find/-/unist-util-find-1.0.1.tgz#1062bbb6928c7a97c6adc89b53745d4c46c222a2"
+  resolved "https://registry.npmjs.org/unist-util-find/-/unist-util-find-1.0.1.tgz#1062bbb6928c7a97c6adc89b53745d4c46c222a2"
   dependencies:
     lodash.iteratee "^4.5.0"
     remark "^5.0.1"