diff --git a/clang-tools-extra/clangd/ConfigYAML.cpp b/clang-tools-extra/clangd/ConfigYAML.cpp
--- a/clang-tools-extra/clangd/ConfigYAML.cpp
+++ b/clang-tools-extra/clangd/ConfigYAML.cpp
@@ -24,6 +24,29 @@
 using llvm::yaml::ScalarNode;
 using llvm::yaml::SequenceNode;
 
+static llvm::Optional<llvm::StringRef>
+bestGuess(llvm::StringRef Search,
+          llvm::ArrayRef<llvm::StringRef> AllowedValues) {
+  unsigned MaxEdit = (Search.size() + 1) / 3;
+  if (!MaxEdit)
+    return llvm::None;
+  llvm::Optional<llvm::StringRef> Result;
+  for (const auto &AllowedValue : AllowedValues) {
+    unsigned EditDistance = Search.edit_distance(AllowedValue, true, MaxEdit);
+    // We can't do better than an edit distance of 1, so just return this and
+    // save computing other values.
+    if (EditDistance == 1U)
+      return AllowedValue;
+    if (EditDistance == MaxEdit && !Result) {
+      Result = AllowedValue;
+    } else if (EditDistance < MaxEdit) {
+      Result = AllowedValue;
+      MaxEdit = EditDistance;
+    }
+  }
+  return Result;
+}
+
 class Parser {
   llvm::SourceMgr &SM;
   bool HadError = false;
@@ -167,6 +190,7 @@
         return;
       }
       llvm::SmallSet<std::string, 8> Seen;
+      llvm::SmallVector<Located<std::string>, 0> UnknownKeys;
       // We *must* consume all items, even on error, or the parser will assert.
       for (auto &KV : llvm::cast<MappingNode>(N)) {
         auto *K = KV.getKey();
@@ -198,9 +222,30 @@
             Warn = UnknownHandler(
                 Located<std::string>(**Key, K->getSourceRange()), *Value);
           if (Warn)
-            Outer->warning("Unknown " + Description + " key " + **Key, *K);
+            UnknownKeys.push_back(std::move(*Key));
         }
       }
+      if (!UnknownKeys.empty())
+        warnUnknownKeys(UnknownKeys, Seen);
+    }
+
+  private:
+    void warnUnknownKeys(llvm::ArrayRef<Located<std::string>> UnknownKeys,
+                         const llvm::SmallSet<std::string, 8> &SeenKeys) const {
+      llvm::SmallVector<llvm::StringRef> UnseenKeys;
+      for (const auto &KeyAndHandler : Keys)
+        if (!SeenKeys.count(KeyAndHandler.first.str()))
+          UnseenKeys.push_back(KeyAndHandler.first);
+
+      for (const Located<std::string> &UnknownKey : UnknownKeys)
+        if (auto BestGuess = bestGuess(*UnknownKey, UnseenKeys))
+          Outer->warning("Unknown " + Description + " key '" + *UnknownKey +
+                             "'; did you mean '" + *BestGuess + "'?",
+                         UnknownKey.Range);
+        else
+          Outer->warning("Unknown " + Description + " key '" + *UnknownKey +
+                             "'",
+                         UnknownKey.Range);
     }
   };
 
@@ -238,16 +283,23 @@
   }
 
   // Report a "hard" error, reflecting a config file that can never be valid.
-  void error(const llvm::Twine &Msg, const Node &N) {
+  void error(const llvm::Twine &Msg, llvm::SMRange Range) {
     HadError = true;
-    SM.PrintMessage(N.getSourceRange().Start, llvm::SourceMgr::DK_Error, Msg,
-                    N.getSourceRange());
+    SM.PrintMessage(Range.Start, llvm::SourceMgr::DK_Error, Msg, Range);
+  }
+
+  // Report a "hard" error, reflecting a config file that can never be valid.
+  void error(const llvm::Twine &Msg, const Node &N) {
+    return error(Msg, N.getSourceRange());
+  }
+  // Report a "soft" error that could be caused by e.g. version skew.
+  void warning(const llvm::Twine &Msg, llvm::SMRange Range) {
+    SM.PrintMessage(Range.Start, llvm::SourceMgr::DK_Warning, Msg, Range);
   }
 
   // Report a "soft" error that could be caused by e.g. version skew.
   void warning(const llvm::Twine &Msg, const Node &N) {
-    SM.PrintMessage(N.getSourceRange().Start, llvm::SourceMgr::DK_Warning, Msg,
-                    N.getSourceRange());
+    return warning(Msg, N.getSourceRange());
   }
 };
 
diff --git a/clang-tools-extra/clangd/test/config.test b/clang-tools-extra/clangd/test/config.test
--- a/clang-tools-extra/clangd/test/config.test
+++ b/clang-tools-extra/clangd/test/config.test
@@ -19,7 +19,7 @@
 # CHECK-NEXT:  "params": {
 # CHECK-NEXT:    "diagnostics": [
 # CHECK-NEXT:      {
-# CHECK-NEXT:        "message": "Unknown Config key Foo",
+# CHECK-NEXT:        "message": "Unknown Config key 'Foo'",
 # CHECK-NEXT:        "range": {
 # CHECK-NEXT:          "end": {
 # CHECK-NEXT:            "character": 3,
diff --git a/clang-tools-extra/clangd/unittests/ConfigProviderTests.cpp b/clang-tools-extra/clangd/unittests/ConfigProviderTests.cpp
--- a/clang-tools-extra/clangd/unittests/ConfigProviderTests.cpp
+++ b/clang-tools-extra/clangd/unittests/ConfigProviderTests.cpp
@@ -79,6 +79,12 @@
   Unknown: 42
 )yaml";
 
+const char *AddFooWithTypoErr = R"yaml(
+CompileFlags:
+  Add: foo
+  Removr: 42
+)yaml";
+
 const char *AddBarBaz = R"yaml(
 CompileFlags:
   Add: bar
@@ -95,7 +101,7 @@
   auto P = Provider::fromYAMLFile(testPath("foo.yaml"), /*Directory=*/"", FS);
   auto Cfg = P->getConfig(Params(), Diags.callback());
   EXPECT_THAT(Diags.Diagnostics,
-              ElementsAre(DiagMessage("Unknown CompileFlags key Unknown")));
+              ElementsAre(DiagMessage("Unknown CompileFlags key 'Unknown'")));
   EXPECT_THAT(Diags.Files, ElementsAre(testPath("foo.yaml")));
   EXPECT_THAT(getAddedArgs(Cfg), ElementsAre("foo"));
   Diags.clear();
@@ -105,6 +111,16 @@
   EXPECT_THAT(Diags.Files, IsEmpty());
   EXPECT_THAT(getAddedArgs(Cfg), ElementsAre("foo"));
 
+  FS.Files["foo.yaml"] = AddFooWithTypoErr;
+  Cfg = P->getConfig(Params(), Diags.callback());
+  EXPECT_THAT(
+      Diags.Diagnostics,
+      ElementsAre(DiagMessage(
+          "Unknown CompileFlags key 'Removr'; did you mean 'Remove'?")));
+  EXPECT_THAT(Diags.Files, ElementsAre(testPath("foo.yaml")));
+  EXPECT_THAT(getAddedArgs(Cfg), ElementsAre("foo"));
+  Diags.clear();
+
   FS.Files["foo.yaml"] = AddBarBaz;
   Cfg = P->getConfig(Params(), Diags.callback());
   EXPECT_THAT(Diags.Diagnostics, IsEmpty()) << "New config, no errors";
@@ -143,7 +159,7 @@
 
   Cfg = P->getConfig(ABCParams, Diags.callback());
   EXPECT_THAT(Diags.Diagnostics,
-              ElementsAre(DiagMessage("Unknown CompileFlags key Unknown")));
+              ElementsAre(DiagMessage("Unknown CompileFlags key 'Unknown'")));
   // FIXME: fails on windows: paths have mixed slashes like C:\a/b\c.yaml
   EXPECT_THAT(Diags.Files,
               ElementsAre(testPath("a/foo.yaml"), testPath("a/b/c/foo.yaml")));
@@ -178,7 +194,7 @@
   FS.Files["foo.yaml"] = AddFooWithErr;
   auto Cfg = P->getConfig(StaleOK, Diags.callback());
   EXPECT_THAT(Diags.Diagnostics,
-              ElementsAre(DiagMessage("Unknown CompileFlags key Unknown")));
+              ElementsAre(DiagMessage("Unknown CompileFlags key 'Unknown'")));
   EXPECT_THAT(getAddedArgs(Cfg), ElementsAre("foo"));
   Diags.clear();
 
diff --git a/clang-tools-extra/clangd/unittests/ConfigYAMLTests.cpp b/clang-tools-extra/clangd/unittests/ConfigYAMLTests.cpp
--- a/clang-tools-extra/clangd/unittests/ConfigYAMLTests.cpp
+++ b/clang-tools-extra/clangd/unittests/ConfigYAMLTests.cpp
@@ -113,7 +113,7 @@
 
   ASSERT_THAT(
       Diags.Diagnostics,
-      ElementsAre(AllOf(DiagMessage("Unknown If key UnknownCondition"),
+      ElementsAre(AllOf(DiagMessage("Unknown If key 'UnknownCondition'"),
                         DiagKind(llvm::SourceMgr::DK_Warning),
                         DiagPos(YAML.range("unknown").start),
                         DiagRange(YAML.range("unknown"))),