diff --git a/utils/CMakeLists.txt b/utils/CMakeLists.txt
index c6e877f..ec13089 100644
--- a/utils/CMakeLists.txt
+++ b/utils/CMakeLists.txt
@@ -1,5 +1,6 @@
 add_subdirectory(CPP)
 add_subdirectory(FPUtil)
+add_subdirectory(LibcTableGenUtil)
 add_subdirectory(HdrGen)
 add_subdirectory(MPFRWrapper)
 add_subdirectory(testutils)
diff --git a/utils/HdrGen/CMakeLists.txt b/utils/HdrGen/CMakeLists.txt
index 65c2d65..8aaaa96 100644
--- a/utils/HdrGen/CMakeLists.txt
+++ b/utils/HdrGen/CMakeLists.txt
@@ -12,4 +12,7 @@
   PublicAPICommand.h
 )
 
+target_include_directories(libc-hdrgen PRIVATE ${LIBC_SOURCE_DIR})
+target_link_libraries(libc-hdrgen PRIVATE LibcTableGenUtil)
+
 add_subdirectory(PrototypeTestGen)
diff --git a/utils/HdrGen/PrototypeTestGen/CMakeLists.txt b/utils/HdrGen/PrototypeTestGen/CMakeLists.txt
index e4ad5c2..c90fde7 100644
--- a/utils/HdrGen/PrototypeTestGen/CMakeLists.txt
+++ b/utils/HdrGen/PrototypeTestGen/CMakeLists.txt
@@ -1,5 +1,5 @@
 add_tablegen(libc-prototype-testgen llvm-libc
   PrototypeTestGen.cpp
-  ../PublicAPICommand.cpp
-  ../Command.cpp
 )
+target_link_libraries(libc-prototype-testgen PRIVATE LibcTableGenUtil)
+target_include_directories(libc-prototype-testgen PRIVATE ${LIBC_SOURCE_DIR})
diff --git a/utils/HdrGen/PrototypeTestGen/PrototypeTestGen.cpp b/utils/HdrGen/PrototypeTestGen/PrototypeTestGen.cpp
index aad451a..918b520 100644
--- a/utils/HdrGen/PrototypeTestGen/PrototypeTestGen.cpp
+++ b/utils/HdrGen/PrototypeTestGen/PrototypeTestGen.cpp
@@ -6,7 +6,7 @@
 //
 //===----------------------------------------------------------------------===//
 
-#include "../PublicAPICommand.h"
+#include "utils/LibcTableGenUtil/APIIndexer.h"
 
 #include "llvm/ADT/StringRef.h"
 #include "llvm/Support/CommandLine.h"
diff --git a/utils/HdrGen/PublicAPICommand.cpp b/utils/HdrGen/PublicAPICommand.cpp
index 11b8258..87b188c 100644
--- a/utils/HdrGen/PublicAPICommand.cpp
+++ b/utils/HdrGen/PublicAPICommand.cpp
@@ -8,32 +8,13 @@
 
 #include "PublicAPICommand.h"
 
+#include "utils/LibcTableGenUtil/APIIndexer.h"
+
 #include "llvm/ADT/StringExtras.h"
 #include "llvm/ADT/StringRef.h"
 #include "llvm/Support/SourceMgr.h"
-#include "llvm/TableGen/Error.h"
 #include "llvm/TableGen/Record.h"
 
-static const char NamedTypeClassName[] = "NamedType";
-static const char PtrTypeClassName[] = "PtrType";
-static const char RestrictedPtrTypeClassName[] = "RestrictedPtrType";
-static const char ConstTypeClassName[] = "ConstType";
-static const char StructTypeClassName[] = "Struct";
-
-static const char StandardSpecClassName[] = "StandardSpec";
-static const char PublicAPIClassName[] = "PublicAPI";
-
-static bool isa(llvm::Record *Def, llvm::Record *TypeClass) {
-  llvm::RecordRecTy *RecordType = Def->getType();
-  llvm::ArrayRef<llvm::Record *> Classes = RecordType->getClasses();
-  // We want exact types. That is, we don't want the classes listed in
-  // spec.td to be subclassed. Hence, we do not want the record |Def|
-  // to be of more than one class type..
-  if (Classes.size() != 1)
-    return false;
-  return Classes[0] == TypeClass;
-}
-
 // Text blocks for macro definitions and type decls can be indented to
 // suit the surrounding tablegen listing. We need to dedent such blocks
 // before writing them out.
@@ -59,129 +40,6 @@
 
 namespace llvm_libc {
 
-bool APIIndexer::isaNamedType(llvm::Record *Def) {
-  return isa(Def, NamedTypeClass);
-}
-
-bool APIIndexer::isaStructType(llvm::Record *Def) {
-  return isa(Def, StructClass);
-}
-
-bool APIIndexer::isaPtrType(llvm::Record *Def) {
-  return isa(Def, PtrTypeClass);
-}
-
-bool APIIndexer::isaConstType(llvm::Record *Def) {
-  return isa(Def, ConstTypeClass);
-}
-
-bool APIIndexer::isaRestrictedPtrType(llvm::Record *Def) {
-  return isa(Def, RestrictedPtrTypeClass);
-}
-
-bool APIIndexer::isaStandardSpec(llvm::Record *Def) {
-  return isa(Def, StandardSpecClass);
-}
-
-bool APIIndexer::isaPublicAPI(llvm::Record *Def) {
-  return isa(Def, PublicAPIClass);
-}
-
-std::string APIIndexer::getTypeAsString(llvm::Record *TypeRecord) {
-  if (isaNamedType(TypeRecord) || isaStructType(TypeRecord)) {
-    return std::string(TypeRecord->getValueAsString("Name"));
-  } else if (isaPtrType(TypeRecord)) {
-    return getTypeAsString(TypeRecord->getValueAsDef("PointeeType")) + " *";
-  } else if (isaConstType(TypeRecord)) {
-    return std::string("const ") +
-           getTypeAsString(TypeRecord->getValueAsDef("UnqualifiedType"));
-  } else if (isaRestrictedPtrType(TypeRecord)) {
-    return getTypeAsString(TypeRecord->getValueAsDef("PointeeType")) +
-           " *__restrict";
-  } else {
-    llvm::PrintFatalError(TypeRecord->getLoc(), "Invalid type.\n");
-  }
-}
-
-void APIIndexer::indexStandardSpecDef(llvm::Record *StandardSpec) {
-  auto HeaderSpecList = StandardSpec->getValueAsListOfDefs("Headers");
-  for (llvm::Record *HeaderSpec : HeaderSpecList) {
-    llvm::StringRef Header = HeaderSpec->getValueAsString("Name");
-    if (!StdHeader.hasValue() || Header == StdHeader) {
-      PublicHeaders.emplace(Header);
-      auto MacroSpecList = HeaderSpec->getValueAsListOfDefs("Macros");
-      // TODO: Trigger a fatal error on duplicate specs.
-      for (llvm::Record *MacroSpec : MacroSpecList)
-        MacroSpecMap[std::string(MacroSpec->getValueAsString("Name"))] =
-            MacroSpec;
-
-      auto TypeSpecList = HeaderSpec->getValueAsListOfDefs("Types");
-      for (llvm::Record *TypeSpec : TypeSpecList)
-        TypeSpecMap[std::string(TypeSpec->getValueAsString("Name"))] = TypeSpec;
-
-      auto FunctionSpecList = HeaderSpec->getValueAsListOfDefs("Functions");
-      for (llvm::Record *FunctionSpec : FunctionSpecList) {
-        FunctionSpecMap[std::string(FunctionSpec->getValueAsString("Name"))] =
-            FunctionSpec;
-      }
-
-      auto EnumerationSpecList =
-          HeaderSpec->getValueAsListOfDefs("Enumerations");
-      for (llvm::Record *EnumerationSpec : EnumerationSpecList) {
-        EnumerationSpecMap[std::string(
-            EnumerationSpec->getValueAsString("Name"))] = EnumerationSpec;
-      }
-    }
-  }
-}
-
-void APIIndexer::indexPublicAPIDef(llvm::Record *PublicAPI) {
-  // While indexing the public API, we do not check if any of the entities
-  // requested is from an included standard. Such a check is done while
-  // generating the API.
-  auto MacroDefList = PublicAPI->getValueAsListOfDefs("Macros");
-  for (llvm::Record *MacroDef : MacroDefList)
-    MacroDefsMap[std::string(MacroDef->getValueAsString("Name"))] = MacroDef;
-
-  auto TypeDeclList = PublicAPI->getValueAsListOfDefs("TypeDeclarations");
-  for (llvm::Record *TypeDecl : TypeDeclList)
-    TypeDeclsMap[std::string(TypeDecl->getValueAsString("Name"))] = TypeDecl;
-
-  auto StructList = PublicAPI->getValueAsListOfStrings("Structs");
-  for (llvm::StringRef StructName : StructList)
-    Structs.insert(std::string(StructName));
-
-  auto FunctionList = PublicAPI->getValueAsListOfStrings("Functions");
-  for (llvm::StringRef FunctionName : FunctionList)
-    Functions.insert(std::string(FunctionName));
-
-  auto EnumerationList = PublicAPI->getValueAsListOfStrings("Enumerations");
-  for (llvm::StringRef EnumerationName : EnumerationList)
-    Enumerations.insert(std::string(EnumerationName));
-}
-
-void APIIndexer::index(llvm::RecordKeeper &Records) {
-  NamedTypeClass = Records.getClass(NamedTypeClassName);
-  PtrTypeClass = Records.getClass(PtrTypeClassName);
-  RestrictedPtrTypeClass = Records.getClass(RestrictedPtrTypeClassName);
-  StructClass = Records.getClass(StructTypeClassName);
-  ConstTypeClass = Records.getClass(ConstTypeClassName);
-  StandardSpecClass = Records.getClass(StandardSpecClassName);
-  PublicAPIClass = Records.getClass(PublicAPIClassName);
-
-  const auto &DefsMap = Records.getDefs();
-  for (auto &Pair : DefsMap) {
-    llvm::Record *Def = Pair.second.get();
-    if (isaStandardSpec(Def))
-      indexStandardSpecDef(Def);
-    if (isaPublicAPI(Def)) {
-      if (!StdHeader.hasValue() ||
-          Def->getValueAsString("HeaderName") == StdHeader)
-        indexPublicAPIDef(Def);
-    }
-  }
-}
-
 void writeAPIFromIndex(APIIndexer &G, llvm::raw_ostream &OS) {
   for (auto &Pair : G.MacroDefsMap) {
     const std::string &Name = Pair.first;
diff --git a/utils/HdrGen/PublicAPICommand.h b/utils/HdrGen/PublicAPICommand.h
index c95ad52..bfe2e5f 100644
--- a/utils/HdrGen/PublicAPICommand.h
+++ b/utils/HdrGen/PublicAPICommand.h
@@ -12,10 +12,8 @@
 #include "Command.h"
 
 #include "llvm/ADT/StringRef.h"
-
-#include <string>
-#include <unordered_map>
-#include <unordered_set>
+#include "llvm/TableGen/Error.h"
+#include "llvm/TableGen/Record.h"
 
 namespace llvm {
 
@@ -36,61 +34,6 @@
            const Command::ErrorReporter &Reporter) const override;
 };
 
-class APIIndexer {
-private:
-  llvm::Optional<llvm::StringRef> StdHeader;
-
-  // TableGen classes in spec.td.
-  llvm::Record *NamedTypeClass;
-  llvm::Record *PtrTypeClass;
-  llvm::Record *RestrictedPtrTypeClass;
-  llvm::Record *ConstTypeClass;
-  llvm::Record *StructClass;
-  llvm::Record *StandardSpecClass;
-  llvm::Record *PublicAPIClass;
-
-  bool isaNamedType(llvm::Record *Def);
-  bool isaStructType(llvm::Record *Def);
-  bool isaPtrType(llvm::Record *Def);
-  bool isaConstType(llvm::Record *Def);
-  bool isaRestrictedPtrType(llvm::Record *Def);
-  bool isaStandardSpec(llvm::Record *Def);
-  bool isaPublicAPI(llvm::Record *Def);
-
-  void indexStandardSpecDef(llvm::Record *StandardSpec);
-  void indexPublicAPIDef(llvm::Record *PublicAPI);
-  void index(llvm::RecordKeeper &Records);
-
-public:
-  using NameToRecordMapping = std::unordered_map<std::string, llvm::Record *>;
-  using NameSet = std::unordered_set<std::string>;
-
-  // This indexes all headers, not just a specified one.
-  explicit APIIndexer(llvm::RecordKeeper &Records) : StdHeader(llvm::None) {
-    index(Records);
-  }
-
-  APIIndexer(llvm::StringRef Header, llvm::RecordKeeper &Records)
-      : StdHeader(Header) {
-    index(Records);
-  }
-
-  // Mapping from names to records defining them.
-  NameToRecordMapping MacroSpecMap;
-  NameToRecordMapping TypeSpecMap;
-  NameToRecordMapping EnumerationSpecMap;
-  NameToRecordMapping FunctionSpecMap;
-  NameToRecordMapping MacroDefsMap;
-  NameToRecordMapping TypeDeclsMap;
-
-  NameSet Structs;
-  NameSet Enumerations;
-  NameSet Functions;
-  NameSet PublicHeaders;
-
-  std::string getTypeAsString(llvm::Record *TypeRecord);
-};
-
 } // namespace llvm_libc
 
 #endif // LLVM_LIBC_UTILS_HDRGEN_PUBLICAPICOMMAND_H
diff --git a/utils/LibcTableGenUtil/APIIndexer.cpp b/utils/LibcTableGenUtil/APIIndexer.cpp
new file mode 100644
index 0000000..934d713
--- /dev/null
+++ b/utils/LibcTableGenUtil/APIIndexer.cpp
@@ -0,0 +1,154 @@
+
+#include "APIIndexer.h"
+
+#include "llvm/ADT/StringExtras.h"
+#include "llvm/ADT/StringRef.h"
+#include "llvm/TableGen/Error.h"
+#include "llvm/TableGen/Record.h"
+
+namespace llvm_libc {
+
+static const char NamedTypeClassName[] = "NamedType";
+static const char PtrTypeClassName[] = "PtrType";
+static const char RestrictedPtrTypeClassName[] = "RestrictedPtrType";
+static const char ConstTypeClassName[] = "ConstType";
+static const char StructTypeClassName[] = "Struct";
+
+static const char StandardSpecClassName[] = "StandardSpec";
+static const char PublicAPIClassName[] = "PublicAPI";
+
+static bool isa(llvm::Record *Def, llvm::Record *TypeClass) {
+  llvm::RecordRecTy *RecordType = Def->getType();
+  llvm::ArrayRef<llvm::Record *> Classes = RecordType->getClasses();
+  // We want exact types. That is, we don't want the classes listed in
+  // spec.td to be subclassed. Hence, we do not want the record |Def|
+  // to be of more than one class type..
+  if (Classes.size() != 1)
+    return false;
+  return Classes[0] == TypeClass;
+}
+
+bool APIIndexer::isaNamedType(llvm::Record *Def) {
+  return isa(Def, NamedTypeClass);
+}
+
+bool APIIndexer::isaStructType(llvm::Record *Def) {
+  return isa(Def, StructClass);
+}
+
+bool APIIndexer::isaPtrType(llvm::Record *Def) {
+  return isa(Def, PtrTypeClass);
+}
+
+bool APIIndexer::isaConstType(llvm::Record *Def) {
+  return isa(Def, ConstTypeClass);
+}
+
+bool APIIndexer::isaRestrictedPtrType(llvm::Record *Def) {
+  return isa(Def, RestrictedPtrTypeClass);
+}
+
+bool APIIndexer::isaStandardSpec(llvm::Record *Def) {
+  return isa(Def, StandardSpecClass);
+}
+
+bool APIIndexer::isaPublicAPI(llvm::Record *Def) {
+  return isa(Def, PublicAPIClass);
+}
+
+std::string APIIndexer::getTypeAsString(llvm::Record *TypeRecord) {
+  if (isaNamedType(TypeRecord) || isaStructType(TypeRecord)) {
+    return std::string(TypeRecord->getValueAsString("Name"));
+  } else if (isaPtrType(TypeRecord)) {
+    return getTypeAsString(TypeRecord->getValueAsDef("PointeeType")) + " *";
+  } else if (isaConstType(TypeRecord)) {
+    return std::string("const ") +
+           getTypeAsString(TypeRecord->getValueAsDef("UnqualifiedType"));
+  } else if (isaRestrictedPtrType(TypeRecord)) {
+    return getTypeAsString(TypeRecord->getValueAsDef("PointeeType")) +
+           " *__restrict";
+  } else {
+    llvm::PrintFatalError(TypeRecord->getLoc(), "Invalid type.\n");
+  }
+}
+
+void APIIndexer::indexStandardSpecDef(llvm::Record *StandardSpec) {
+  auto HeaderSpecList = StandardSpec->getValueAsListOfDefs("Headers");
+  for (llvm::Record *HeaderSpec : HeaderSpecList) {
+    llvm::StringRef Header = HeaderSpec->getValueAsString("Name");
+    if (!StdHeader.hasValue() || Header == StdHeader) {
+      PublicHeaders.emplace(Header);
+      auto MacroSpecList = HeaderSpec->getValueAsListOfDefs("Macros");
+      // TODO: Trigger a fatal error on duplicate specs.
+      for (llvm::Record *MacroSpec : MacroSpecList)
+        MacroSpecMap[std::string(MacroSpec->getValueAsString("Name"))] =
+            MacroSpec;
+
+      auto TypeSpecList = HeaderSpec->getValueAsListOfDefs("Types");
+      for (llvm::Record *TypeSpec : TypeSpecList)
+        TypeSpecMap[std::string(TypeSpec->getValueAsString("Name"))] = TypeSpec;
+
+      auto FunctionSpecList = HeaderSpec->getValueAsListOfDefs("Functions");
+      for (llvm::Record *FunctionSpec : FunctionSpecList) {
+        FunctionSpecMap[std::string(FunctionSpec->getValueAsString("Name"))] =
+            FunctionSpec;
+      }
+
+      auto EnumerationSpecList =
+          HeaderSpec->getValueAsListOfDefs("Enumerations");
+      for (llvm::Record *EnumerationSpec : EnumerationSpecList) {
+        EnumerationSpecMap[std::string(
+            EnumerationSpec->getValueAsString("Name"))] = EnumerationSpec;
+      }
+    }
+  }
+}
+
+void APIIndexer::indexPublicAPIDef(llvm::Record *PublicAPI) {
+  // While indexing the public API, we do not check if any of the entities
+  // requested is from an included standard. Such a check is done while
+  // generating the API.
+  auto MacroDefList = PublicAPI->getValueAsListOfDefs("Macros");
+  for (llvm::Record *MacroDef : MacroDefList)
+    MacroDefsMap[std::string(MacroDef->getValueAsString("Name"))] = MacroDef;
+
+  auto TypeDeclList = PublicAPI->getValueAsListOfDefs("TypeDeclarations");
+  for (llvm::Record *TypeDecl : TypeDeclList)
+    TypeDeclsMap[std::string(TypeDecl->getValueAsString("Name"))] = TypeDecl;
+
+  auto StructList = PublicAPI->getValueAsListOfStrings("Structs");
+  for (llvm::StringRef StructName : StructList)
+    Structs.insert(std::string(StructName));
+
+  auto FunctionList = PublicAPI->getValueAsListOfStrings("Functions");
+  for (llvm::StringRef FunctionName : FunctionList)
+    Functions.insert(std::string(FunctionName));
+
+  auto EnumerationList = PublicAPI->getValueAsListOfStrings("Enumerations");
+  for (llvm::StringRef EnumerationName : EnumerationList)
+    Enumerations.insert(std::string(EnumerationName));
+}
+
+void APIIndexer::index(llvm::RecordKeeper &Records) {
+  NamedTypeClass = Records.getClass(NamedTypeClassName);
+  PtrTypeClass = Records.getClass(PtrTypeClassName);
+  RestrictedPtrTypeClass = Records.getClass(RestrictedPtrTypeClassName);
+  StructClass = Records.getClass(StructTypeClassName);
+  ConstTypeClass = Records.getClass(ConstTypeClassName);
+  StandardSpecClass = Records.getClass(StandardSpecClassName);
+  PublicAPIClass = Records.getClass(PublicAPIClassName);
+
+  const auto &DefsMap = Records.getDefs();
+  for (auto &Pair : DefsMap) {
+    llvm::Record *Def = Pair.second.get();
+    if (isaStandardSpec(Def))
+      indexStandardSpecDef(Def);
+    if (isaPublicAPI(Def)) {
+      if (!StdHeader.hasValue() ||
+          Def->getValueAsString("HeaderName") == StdHeader)
+        indexPublicAPIDef(Def);
+    }
+  }
+}
+
+} // namespace llvm_libc
diff --git a/utils/LibcTableGenUtil/APIIndexer.h b/utils/LibcTableGenUtil/APIIndexer.h
new file mode 100644
index 0000000..a0f0acf
--- /dev/null
+++ b/utils/LibcTableGenUtil/APIIndexer.h
@@ -0,0 +1,66 @@
+
+#include "llvm/ADT/StringRef.h"
+#include "llvm/TableGen/Record.h"
+
+#include <string>
+#include <unordered_map>
+#include <unordered_set>
+
+namespace llvm_libc {
+
+class APIIndexer {
+private:
+  llvm::Optional<llvm::StringRef> StdHeader;
+
+  // TableGen classes in spec.td.
+  llvm::Record *NamedTypeClass;
+  llvm::Record *PtrTypeClass;
+  llvm::Record *RestrictedPtrTypeClass;
+  llvm::Record *ConstTypeClass;
+  llvm::Record *StructClass;
+  llvm::Record *StandardSpecClass;
+  llvm::Record *PublicAPIClass;
+
+  bool isaNamedType(llvm::Record *Def);
+  bool isaStructType(llvm::Record *Def);
+  bool isaPtrType(llvm::Record *Def);
+  bool isaConstType(llvm::Record *Def);
+  bool isaRestrictedPtrType(llvm::Record *Def);
+  bool isaStandardSpec(llvm::Record *Def);
+  bool isaPublicAPI(llvm::Record *Def);
+
+  void indexStandardSpecDef(llvm::Record *StandardSpec);
+  void indexPublicAPIDef(llvm::Record *PublicAPI);
+  void index(llvm::RecordKeeper &Records);
+
+public:
+  using NameToRecordMapping = std::unordered_map<std::string, llvm::Record *>;
+  using NameSet = std::unordered_set<std::string>;
+
+  // This indexes all headers, not just a specified one.
+  explicit APIIndexer(llvm::RecordKeeper &Records) : StdHeader(llvm::None) {
+    index(Records);
+  }
+
+  APIIndexer(llvm::StringRef Header, llvm::RecordKeeper &Records)
+      : StdHeader(Header) {
+    index(Records);
+  }
+
+  // Mapping from names to records defining them.
+  NameToRecordMapping MacroSpecMap;
+  NameToRecordMapping TypeSpecMap;
+  NameToRecordMapping EnumerationSpecMap;
+  NameToRecordMapping FunctionSpecMap;
+  NameToRecordMapping MacroDefsMap;
+  NameToRecordMapping TypeDeclsMap;
+
+  NameSet Structs;
+  NameSet Enumerations;
+  NameSet Functions;
+  NameSet PublicHeaders;
+
+  std::string getTypeAsString(llvm::Record *TypeRecord);
+};
+
+} // namespace llvm_libc
diff --git a/utils/LibcTableGenUtil/CMakeLists.txt b/utils/LibcTableGenUtil/CMakeLists.txt
new file mode 100644
index 0000000..ae887a8
--- /dev/null
+++ b/utils/LibcTableGenUtil/CMakeLists.txt
@@ -0,0 +1,7 @@
+add_llvm_library(
+  LibcTableGenUtil
+  APIIndexer.cpp
+  APIIndexer.h
+  LINK_COMPONENTS Support
+)
+target_include_directories(LibcTableGenUtil PUBLIC ${LIBC_SOURCE_DIR})