diff --git a/clang-tools-extra/clang-tidy/readability/NamespaceCommentCheck.cpp b/clang-tools-extra/clang-tidy/readability/NamespaceCommentCheck.cpp
--- a/clang-tools-extra/clang-tidy/readability/NamespaceCommentCheck.cpp
+++ b/clang-tools-extra/clang-tidy/readability/NamespaceCommentCheck.cpp
@@ -23,9 +23,10 @@
 NamespaceCommentCheck::NamespaceCommentCheck(StringRef Name,
                                              ClangTidyContext *Context)
     : ClangTidyCheck(Name, Context),
-      NamespaceCommentPattern("^/[/*] *(end (of )?)? *(anonymous|unnamed)? *"
-                              "namespace( +([a-zA-Z0-9_:]+))?\\.? *(\\*/)?$",
-                              llvm::Regex::IgnoreCase),
+      NamespaceCommentPattern(
+          "^/[/*] *(end (of )?)? *(anonymous|unnamed)? *"
+          "namespace( +(((inline )|([a-zA-Z0-9_:]))+))?\\.? *(\\*/)?$",
+          llvm::Regex::IgnoreCase),
       ShortNamespaceLines(Options.get("ShortNamespaceLines", 1u)),
       SpacesBeforeComments(Options.get("SpacesBeforeComments", 1u)) {}
 
@@ -67,8 +68,10 @@
     } else if (Nesting == 0) {
       if (T->is(tok::raw_identifier)) {
         StringRef ID = T->getRawIdentifier();
-        if (ID != "namespace" && ID != "inline")
+        if (ID != "namespace")
           Result.append(std::string(ID));
+        if (ID == "inline")
+          Result.append(" ");
       } else if (T->is(tok::coloncolon)) {
         Result.append("::");
       } else { // Any other kind of token is unexpected here.
diff --git a/clang-tools-extra/docs/ReleaseNotes.rst b/clang-tools-extra/docs/ReleaseNotes.rst
--- a/clang-tools-extra/docs/ReleaseNotes.rst
+++ b/clang-tools-extra/docs/ReleaseNotes.rst
@@ -163,6 +163,10 @@
   <clang-tidy/checks/bugprone/reserved-identifier>`, so that it does not warn
   on macros starting with underscore and lowercase letter.
 
+- Improved :doc:`llvm-namespace-comment
+  <clang-tidy/checks/llvm/namespace-comment>` check to provide fixes for
+  ``inline`` namespaces in the same format as :program:`clang-format`.
+
 Removed checks
 ^^^^^^^^^^^^^^
 
diff --git a/clang-tools-extra/test/clang-tidy/checkers/google/readability-namespace-comments-c++17.cpp b/clang-tools-extra/test/clang-tidy/checkers/google/readability-namespace-comments-c++17.cpp
--- a/clang-tools-extra/test/clang-tidy/checkers/google/readability-namespace-comments-c++17.cpp
+++ b/clang-tools-extra/test/clang-tidy/checkers/google/readability-namespace-comments-c++17.cpp
@@ -7,11 +7,39 @@
 void f();
 
 
-// CHECK-MESSAGES: :[[@LINE+4]]:1: warning: namespace 'n3::n4' not terminated with
-// CHECK-MESSAGES: :[[@LINE-7]]:23: note: namespace 'n3::n4' starts here
+// CHECK-MESSAGES: :[[@LINE+4]]:1: warning: namespace 'n3::inline n4' not terminated with
+// CHECK-MESSAGES: :[[@LINE-7]]:23: note: namespace 'n3::inline n4' starts here
 // CHECK-MESSAGES: :[[@LINE+2]]:2: warning: namespace 'n1::n2' not terminated with a closing comment [google-readability-namespace-comments]
 // CHECK-MESSAGES: :[[@LINE-10]]:11: note: namespace 'n1::n2' starts here
 }}
-// CHECK-FIXES: }  // namespace n3::n4
+// CHECK-FIXES: }  // namespace n3::inline n4
 // CHECK-FIXES: }  // namespace n1::n2
 
+namespace n7::inline n8 {
+// make namespace above 10 lines
+
+
+
+
+
+
+
+
+
+
+} // namespace n7::inline n8
+
+namespace n9::inline n10 {
+// make namespace above 10 lines
+
+
+
+
+
+
+
+
+
+
+} // namespace n9::n10
+// CHECK-MESSAGES: :[[@LINE-1]]:2: warning: namespace 'n9::inline n10' ends with a comment that refers to a wrong namespace 'n9::n10' [google-readability-namespace-comments]