diff --git a/src/librustdoc/config.rs b/src/librustdoc/config.rs
index 19ea781430041..fe4e2bd091519 100644
--- a/src/librustdoc/config.rs
+++ b/src/librustdoc/config.rs
@@ -344,7 +344,6 @@ impl Options {
                             .map(|s| PathBuf::from(&s))
                             .unwrap_or_else(|| PathBuf::from("doc"));
         let mut cfgs = matches.opt_strs("cfg");
-        cfgs.push("rustdoc".to_string());
         if should_test {
             cfgs.push("doctest".to_string());
         }
diff --git a/src/librustdoc/core.rs b/src/librustdoc/core.rs
index 010e4cf6cd0d5..00265caa965ea 100644
--- a/src/librustdoc/core.rs
+++ b/src/librustdoc/core.rs
@@ -234,7 +234,7 @@ pub fn run_core(options: RustdocOptions) -> (clean::Crate, RenderInfo, RenderOpt
         error_format,
         libs,
         externs,
-        cfgs,
+        mut cfgs,
         codegen_options,
         debugging_options,
         target,
@@ -250,6 +250,9 @@ pub fn run_core(options: RustdocOptions) -> (clean::Crate, RenderInfo, RenderOpt
         ..
     } = options;
 
+    // Add the rustdoc cfg into the doc build.
+    cfgs.push("rustdoc".to_string());
+
     let cpath = Some(input.clone());
     let input = Input::File(input);
 
diff --git a/src/librustdoc/test.rs b/src/librustdoc/test.rs
index 6576165b6ce74..3e77ca47e8a6a 100644
--- a/src/librustdoc/test.rs
+++ b/src/librustdoc/test.rs
@@ -62,9 +62,11 @@ pub fn run(options: Options) -> i32 {
         ..config::Options::default()
     };
 
+    let mut cfgs = options.cfgs.clone();
+    cfgs.push("rustdoc".to_owned());
     let config = interface::Config {
         opts: sessopts,
-        crate_cfg: config::parse_cfgspecs(options.cfgs.clone()),
+        crate_cfg: config::parse_cfgspecs(cfgs),
         input,
         input_path: None,
         output_file: None,
diff --git a/src/test/rustdoc-ui/doc-test-rustdoc-feature.rs b/src/test/rustdoc-ui/doc-test-rustdoc-feature.rs
new file mode 100644
index 0000000000000..d0ead4136575f
--- /dev/null
+++ b/src/test/rustdoc-ui/doc-test-rustdoc-feature.rs
@@ -0,0 +1,14 @@
+// build-pass
+// compile-flags:--test
+// normalize-stdout-test: "src/test/rustdoc-ui" -> "$$DIR"
+
+#![feature(doc_cfg)]
+
+// Make sure `cfg(rustdoc)` is set when finding doctests but not inside the doctests.
+
+/// ```
+/// #![feature(doc_cfg)]
+/// assert!(!cfg!(rustdoc));
+/// ```
+#[cfg(rustdoc)]
+pub struct Foo;
diff --git a/src/test/rustdoc-ui/doc-test-rustdoc-feature.stdout b/src/test/rustdoc-ui/doc-test-rustdoc-feature.stdout
new file mode 100644
index 0000000000000..f2525c2dbec21
--- /dev/null
+++ b/src/test/rustdoc-ui/doc-test-rustdoc-feature.stdout
@@ -0,0 +1,6 @@
+
+running 1 test
+test $DIR/doc-test-rustdoc-feature.rs - Foo (line 9) ... ok
+
+test result: ok. 1 passed; 0 failed; 0 ignored; 0 measured; 0 filtered out
+