diff --git a/clang-tools-extra/clangd/ClangdServer.cpp b/clang-tools-extra/clangd/ClangdServer.cpp
--- a/clang-tools-extra/clangd/ClangdServer.cpp
+++ b/clang-tools-extra/clangd/ClangdServer.cpp
@@ -30,6 +30,7 @@
 #include "support/Logger.h"
 #include "support/Markup.h"
 #include "support/MemoryTree.h"
+#include "support/Path.h"
 #include "support/ThreadsafeFS.h"
 #include "support/Trace.h"
 #include "clang/Format/Format.h"
@@ -213,6 +214,7 @@
       if (!File.empty()) {
         assert(llvm::sys::path::is_absolute(File));
         llvm::sys::path::native(File, PosixPath, llvm::sys::path::Style::posix);
+        PosixPath = maybeCaseFoldPath(PosixPath);
         Params.Path = PosixPath.str();
       }
 
diff --git a/clang-tools-extra/clangd/ConfigCompile.cpp b/clang-tools-extra/clangd/ConfigCompile.cpp
--- a/clang-tools-extra/clangd/ConfigCompile.cpp
+++ b/clang-tools-extra/clangd/ConfigCompile.cpp
@@ -31,6 +31,7 @@
 #include "Features.inc"
 #include "TidyProvider.h"
 #include "support/Logger.h"
+#include "support/Path.h"
 #include "support/Trace.h"
 #include "llvm/ADT/None.h"
 #include "llvm/ADT/Optional.h"
@@ -101,9 +102,11 @@
   // Normalized Fragment::SourceInfo::Directory.
   std::string FragmentDirectory;
 
-  llvm::Optional<llvm::Regex> compileRegex(const Located<std::string> &Text) {
+  llvm::Optional<llvm::Regex>
+  compileRegex(const Located<std::string> &Text,
+               llvm::Regex::RegexFlags Flags = llvm::Regex::NoFlags) {
     std::string Anchored = "^(" + *Text + ")$";
-    llvm::Regex Result(Anchored);
+    llvm::Regex Result(Anchored, Flags);
     std::string RegexError;
     if (!Result.isValid(RegexError)) {
       diag(Error, "Invalid regex " + Anchored + ": " + RegexError, Text.Range);
@@ -184,6 +187,7 @@
       FragmentDirectory = llvm::sys::path::convert_to_slash(F.Source.Directory);
       if (FragmentDirectory.back() != '/')
         FragmentDirectory += '/';
+      FragmentDirectory = maybeCaseFoldPath(FragmentDirectory);
     }
     compile(std::move(F.If));
     compile(std::move(F.CompileFlags));
@@ -195,9 +199,17 @@
     if (F.HasUnrecognizedCondition)
       Out.Conditions.push_back([&](const Params &) { return false; });
 
+#if defined(_WIN32) || defined(__APPLE__)
+    // When matching paths via regex on Windows/Apple they should be treated
+    // case insensitively.
+    llvm::Regex::RegexFlags Flags = llvm::Regex::IgnoreCase;
+#else
+    llvm::Regex::RegexFlags Flags = llvm::Regex::NoFlags;
+#endif
+
     auto PathMatch = std::make_unique<std::vector<llvm::Regex>>();
     for (auto &Entry : F.PathMatch) {
-      if (auto RE = compileRegex(Entry))
+      if (auto RE = compileRegex(Entry, Flags))
         PathMatch->push_back(std::move(*RE));
     }
     if (!PathMatch->empty()) {
@@ -218,7 +230,7 @@
 
     auto PathExclude = std::make_unique<std::vector<llvm::Regex>>();
     for (auto &Entry : F.PathExclude) {
-      if (auto RE = compileRegex(Entry))
+      if (auto RE = compileRegex(Entry, Flags))
         PathExclude->push_back(std::move(*RE));
     }
     if (!PathExclude->empty()) {
@@ -347,7 +359,7 @@
                                 llvm::sys::path::Style::posix);
     if (!AbsPath)
       return;
-    Spec.MountPoint = std::move(*AbsPath);
+    Spec.MountPoint = maybeCaseFoldPath(std::move(*AbsPath));
     Out.Apply.push_back([Spec(std::move(Spec))](const Params &P, Config &C) {
       if (!P.Path.startswith(Spec.MountPoint))
         return;
diff --git a/clang-tools-extra/clangd/unittests/ConfigCompileTests.cpp b/clang-tools-extra/clangd/unittests/ConfigCompileTests.cpp
--- a/clang-tools-extra/clangd/unittests/ConfigCompileTests.cpp
+++ b/clang-tools-extra/clangd/unittests/ConfigCompileTests.cpp
@@ -99,6 +99,19 @@
   Frag.If.PathMatch.emplace_back("ba*r");
   EXPECT_FALSE(compileAndApply());
   EXPECT_THAT(Diags.Diagnostics, IsEmpty());
+
+#if defined(_WIN32) || defined(__APPLE__)
+  // Only matches case-insensitively.
+  Frag = {};
+  Frag.If.PathMatch.emplace_back("B*R");
+  EXPECT_TRUE(compileAndApply());
+  EXPECT_THAT(Diags.Diagnostics, IsEmpty());
+
+  Frag = {};
+  Frag.If.PathExclude.emplace_back("B*R");
+  EXPECT_FALSE(compileAndApply());
+  EXPECT_THAT(Diags.Diagnostics, IsEmpty());
+#endif
 }
 
 TEST_F(ConfigCompileTests, CompileCommands) {
@@ -372,14 +385,14 @@
   compileAndApply();
   ASSERT_THAT(Diags.Diagnostics, IsEmpty());
   ASSERT_TRUE(Conf.Index.External);
-  EXPECT_THAT(Conf.Index.External->MountPoint, FooPath);
+  EXPECT_TRUE(pathEqual(Conf.Index.External->MountPoint, FooPath));
 
   // None defaults to ".".
   Frag = GetFrag(FooPath, llvm::None);
   compileAndApply();
   ASSERT_THAT(Diags.Diagnostics, IsEmpty());
   ASSERT_TRUE(Conf.Index.External);
-  EXPECT_THAT(Conf.Index.External->MountPoint, FooPath);
+  EXPECT_TRUE(pathEqual(Conf.Index.External->MountPoint, FooPath));
 
   // Without a file, external index is empty.
   Parm.Path = "";
@@ -405,7 +418,21 @@
   compileAndApply();
   ASSERT_THAT(Diags.Diagnostics, IsEmpty());
   ASSERT_TRUE(Conf.Index.External);
-  EXPECT_THAT(Conf.Index.External->MountPoint, FooPath);
+  EXPECT_TRUE(pathEqual(Conf.Index.External->MountPoint, FooPath));
+
+#if defined(_WIN32) || defined(__APPLE__)
+  // Only matches case-insensitively.
+  BazPath = testPath("fOo/baz.h", llvm::sys::path::Style::posix);
+  BazPath = llvm::sys::path::convert_to_slash(BazPath);
+  Parm.Path = BazPath;
+
+  FooPath = testPath("FOO/", llvm::sys::path::Style::posix);
+  Frag = GetFrag("", FooPath.c_str());
+  compileAndApply();
+  ASSERT_THAT(Diags.Diagnostics, IsEmpty());
+  ASSERT_TRUE(Conf.Index.External);
+  EXPECT_TRUE(pathEqual(Conf.Index.External->MountPoint, FooPath));
+#endif
 }
 } // namespace
 } // namespace config