diff --git a/README.md b/README.md
index 6f2de5e..c527586 100644
--- a/README.md
+++ b/README.md
@@ -13,7 +13,7 @@ SourceWeb currently runs on Linux and OS X.
 
 SourceWeb is written in C++11.  The indexer links against Clang's C++ API.
 Clang's C++ APIs are not compatible between releases, so this version of
-SourceWeb requires exactly Clang 4.0.  The GUI uses Qt 4.6 or later.  Follow
+SourceWeb requires exactly Clang 6.0.  The GUI uses Qt 4.6 or later.  Follow
 the build instructions to satisfy these dependencies.
 
 
@@ -24,7 +24,7 @@ Install prerequisite packages:
 Debian-based:
 
     sudo apt-get install make g++ libqt4-dev zlib1g-dev libncurses5-dev \
-                         libclang-3.8-dev llvm-3.8-dev
+                         libclang-6.0-dev llvm-6.0-dev
 
 Fedora/CentOS:
 
diff --git a/check-clang.pri b/check-clang.pri
index 1b6b655..3110232 100644
--- a/check-clang.pri
+++ b/check-clang.pri
@@ -3,7 +3,7 @@
 # Clang installation.
 #
 
-REQUIRED_CLANG_VERSION = 4.0
+REQUIRED_CLANG_VERSION = 6.0
 
 equals(CLANG_DIR, "") {
     warning("The CLANG_DIR qmake variable is unset.")
@@ -29,9 +29,7 @@ checkClangRequire($${CLANG_DIR}/include/clang/AST/ASTContext.h)
 CLANG_LIBS = \
     clangFrontend clangSerialization clangDriver \
     clangTooling clangParse clangSema clangAnalysis \
-    clangEdit clangAST clangLex clangBasic \
-    LLVMMC LLVMMCParser LLVMObject LLVMAsmParser LLVMCore LLVMProfileData LLVMSupport \
-    LLVMOption LLVMBitWriter LLVMBitReader LLVMDemangle
+    clangEdit clangAST clangLex clangBasic LLVM-6.0
 for(CLANG_LIB, CLANG_LIBS) {
-    checkClangRequire($${CLANG_DIR}/lib/lib$${CLANG_LIB}.a)
+    checkClangRequire($${CLANG_DIR}/lib/lib$${CLANG_LIB}.so)
 }
diff --git a/clang-indexer/IndexerPPCallbacks.h b/clang-indexer/IndexerPPCallbacks.h
index b7ce29a..3fc4f1c 100644
--- a/clang-indexer/IndexerPPCallbacks.h
+++ b/clang-indexer/IndexerPPCallbacks.h
@@ -44,7 +44,7 @@ class IndexerPPCallbacks : public clang::PPCallbacks
     virtual void MacroDefined(const clang::Token &macroNameToken,
                               const clang::MacroDirective *md) override;
     virtual void MacroUndefined(const clang::Token &macroNameTok,
-                                const clang::MacroDefinition &md) override;
+                                const clang::MacroDefinition &md);
     virtual void Defined(const clang::Token &macroNameToken,
                          const clang::MacroDefinition &md,
                          clang::SourceRange range) override;
diff --git a/configure b/configure
index ee8f56b..889c3e8 100755
--- a/configure
+++ b/configure
@@ -1,7 +1,7 @@
 #!/bin/sh
 set -u
 
-CLANG_VER=4.0
+CLANG_VER=6.0
 SRCDIR=$(cd "$(dirname "$0")" && pwd)
 
 usage() {
@@ -76,7 +76,7 @@ find_clang() {
     fi
     for ITEM in \
             include/clang/AST/ASTContext.h \
-            lib/libclangTooling.a \
+            lib/libclangTooling.so \
             lib/libLLVMCore.a \
     ; do
         ITEM_PATH=$CANDIDATE/$ITEM