Index: clang/docs/ClangFormatStyleOptions.rst
===================================================================
--- clang/docs/ClangFormatStyleOptions.rst
+++ clang/docs/ClangFormatStyleOptions.rst
@@ -935,6 +935,28 @@
       extern "C" {
       int foo();
       }
+  
+      true:
+      #ifdef __cplusplus
+      extern "C" {
+      #endif
+  
+          void f(void);
+  
+      #ifdef __cplusplus
+      }
+      #endif
+      
+      false:
+      #ifdef __cplusplus
+      extern "C" {
+      #endif
+  
+      void f(void);
+  
+      #ifdef __cplusplus
+      }
+      #endif
 
   * ``bool BeforeCatch`` Wrap before ``catch``.
 
Index: clang/include/clang/Format/Format.h
===================================================================
--- clang/include/clang/Format/Format.h
+++ clang/include/clang/Format/Format.h
@@ -977,6 +977,29 @@
     ///   } catch () {
     ///   }
     /// \endcode
+    /// \code
+    ///  true:
+    /// #ifdef __cplusplus
+    /// extern "C" {
+    /// #endif
+    ///
+    ///     void f(void);
+    ///
+    /// #ifdef __cplusplus
+    /// }
+    /// #endif
+    ///
+    /// false:
+    /// #ifdef __cplusplus
+    /// extern "C" {
+    /// #endif
+    ///
+    /// void f(void);
+    ///
+    /// #ifdef __cplusplus
+    /// }
+    /// #endif
+    /// \endcode
     bool BeforeCatch;
     /// Wrap before ``else``.
     /// \code
Index: clang/lib/Format/UnwrappedLineParser.cpp
===================================================================
--- clang/lib/Format/UnwrappedLineParser.cpp
+++ clang/lib/Format/UnwrappedLineParser.cpp
@@ -1086,7 +1086,6 @@
       nextToken();
       if (FormatTok->Tok.is(tok::l_brace)) {
         if (Style.BraceWrapping.AfterExternBlock) {
-          addUnwrappedLine();
           parseBlock(/*MustBeDeclaration=*/true);
         } else {
           parseBlock(/*MustBeDeclaration=*/true, /*AddLevel=*/false);
Index: clang/unittests/Format/FormatTest.cpp
===================================================================
--- clang/unittests/Format/FormatTest.cpp
+++ clang/unittests/Format/FormatTest.cpp
@@ -2462,14 +2462,18 @@
 
   Style.BraceWrapping.AfterExternBlock = true;
   Style.BraceWrapping.SplitEmptyRecord = false;
-  verifyFormat("extern \"C\"\n"
-               "{}",
-               Style);
-  verifyFormat("extern \"C\"\n"
-               "{\n"
+  verifyFormat("extern \"C\" {}", Style);
+  verifyFormat("extern \"C\" {\n"
                "  int foo();\n"
                "}",
                Style);
+
+  Style.BraceWrapping.AfterExternBlock = false;
+  verifyFormat("extern \"C\" {}", Style);
+  verifyFormat("extern \"C\" {\n"
+               "int foo();\n"
+               "}",
+               Style);
 }
 
 TEST_F(FormatTest, FormatsInlineASM) {