diff --git a/libc/CMakeLists.txt b/libc/CMakeLists.txt
--- a/libc/CMakeLists.txt
+++ b/libc/CMakeLists.txt
@@ -78,8 +78,8 @@
 # The lib and test directories are added at the very end as tests
 # and libraries potentially draw from the components present in all
 # of the other directories.
-add_subdirectory(lib)
 if(LLVM_INCLUDE_TESTS)
   add_subdirectory(test)
   add_subdirectory(fuzzing)
 endif()
+add_subdirectory(lib)
diff --git a/libc/cmake/modules/LLVMLibCLibraryRules.cmake b/libc/cmake/modules/LLVMLibCLibraryRules.cmake
--- a/libc/cmake/modules/LLVMLibCLibraryRules.cmake
+++ b/libc/cmake/modules/LLVMLibCLibraryRules.cmake
@@ -90,6 +90,7 @@
 
   get_fq_deps_list(fq_deps_list ${ENTRYPOINT_LIBRARY_DEPENDS})
   get_object_files_for_entrypoint_library(obj_list ${fq_deps_list})
+  set(entrypoint_list  "")
   foreach(dep IN LISTS fq_deps_list)
     get_target_property(dep_type ${dep} "TARGET_TYPE")
     if(NOT (${dep_type} STREQUAL ${ENTRYPOINT_OBJ_TARGET_TYPE}))
@@ -97,7 +98,9 @@
                           "not an 'add_entrypoint_object' target.")
     endif()
     get_entrypoint_object_file(${dep} objfile)
+    get_target_property(entrypoint ${dep} "ENTRYPOINT_NAME")
     list(APPEND obj_list ${objfile})
+    list(APPEND entrypoint_list ${entrypoint})
   endforeach(dep)
   list(REMOVE_DUPLICATES obj_list)
 
@@ -112,6 +115,12 @@
     ALL
     DEPENDS ${library_file}
   )
+  set_target_properties(
+    ${target_name}
+    PROPERTIES
+    LIBRARY_FILE ${library_file}
+    ENTRYPOINTS_LIST "${entrypoint_list}"
+  )
 endfunction(add_entrypoint_library)
 
 # Rule to build a shared library of redirector objects.
@@ -200,3 +209,106 @@
       "DEPS" "${fq_deps_list}"
   )
 endfunction(add_header_library)
+
+# Rule to add a libc public integration test.
+# Usage
+#    add_libc_public_integration_test(
+#      <target name>
+#      LIBS <list of public libraries to link against>
+#    )
+function(add_libc_public_integration_test target_name)
+  if(NOT LLVM_INCLUDE_TESTS)
+    return()
+  endif()
+
+  cmake_parse_arguments(
+    "LIBC_INTTEST"
+    "" # No option arguments
+    "" # No Single value arguments
+    "LIBS;PUBLIC_HDRS" # Multi value arguments
+    ${ARGN}
+  )
+
+  set(public_test ${CMAKE_CURRENT_BINARY_DIR}/${target_name}.cpp)
+
+  set(entrypoints_list "")
+  foreach(lib IN LISTS LIBC_INTTEST_LIBS)
+    get_target_property(entrypoints ${lib} "ENTRYPOINTS_LIST")
+    list(APPEND entrypoints_list ${entrypoints})
+  endforeach()
+  # TODO: Remove these when they are added to the TableGen.
+  list(REMOVE_ITEM entrypoints_list "__assert_fail" "__errno_location")
+  list(TRANSFORM entrypoints_list PREPEND "-e=")
+
+  # Generate integration test souce code.
+  add_custom_command(
+    OUTPUT ${public_test}
+    COMMAND $<TARGET_FILE:libc-prototype-testgen> -o ${public_test}
+            ${entrypoints_list}
+            -I ${LIBC_SOURCE_DIR}
+            ${LIBC_SOURCE_DIR}/config/${LIBC_TARGET_OS}/api.td
+
+    DEPENDS ${LIBC_SOURCE_DIR}/config/${LIBC_TARGET_OS}/api.td
+            libc-prototype-testgen ${LIBC_INTTEST_PUBLIC_HDRS}
+  )
+
+  add_executable(
+    ${target_name}
+    EXCLUDE_FROM_ALL
+    ${public_test}
+  )
+  # Blank out default include directories to prevent accidentally including
+  # system headers or our own internal headers.
+  set_target_properties(
+    ${target_name}
+    PROPERTIES
+    INCLUDE_DIRECTORIES ""
+  )
+  # Only include we need is the include for cpp::IsSame and our generated
+  # public headers.
+  target_include_directories(
+    ${target_name} BEFORE
+    PRIVATE
+      "${LIBC_SOURCE_DIR}/utils/CPP"
+      "${LIBC_BUILD_DIR}/include"
+  )
+  target_compile_options(
+    ${target_name}
+    PRIVATE
+    -ffreestanding
+  )
+  target_link_options(
+    ${target_name}
+    PRIVATE "-nostdlib"
+  )
+  set(library_files)
+  foreach(library_name IN LISTS LIBC_INTTEST_LIBS)
+    get_target_property(library_file ${library_name} "LIBRARY_FILE")
+    list(APPEND library_files ${library_file})
+  endforeach()
+
+  if(COMPILER_RESOURCE_DIR AND LLVM_LIBC_ENABLE_LINTING)
+    add_custom_target(
+      ${target_name}-tidy
+      VERBATIM
+      COMMAND $<TARGET_FILE:clang-tidy> --system-headers
+        --checks=-*,llvmlibc-restrict-system-libc-headers
+        "--extra-arg=-resource-dir=${COMPILER_RESOURCE_DIR}"
+        --header-filter=.*
+        --warnings-as-errors=llvmlibc-*
+        "-config={CheckOptions: [{key: llvmlibc-restrict-system-libc-headers.Includes, value: '-*, linux/*, asm/*.h, asm-generic/*.h'}]}"
+        --quiet
+        -p ${PROJECT_BINARY_DIR}
+        ${public_test}
+      DEPENDS
+        clang-tidy ${public_test}
+    )
+    add_dependencies(check-libc ${target_name}-tidy)
+  endif()
+
+  target_link_libraries(${target_name}
+    PRIVATE
+    ${library_files}
+  )
+  add_dependencies(check-libc ${target_name})
+endfunction(add_libc_public_integration_test)
diff --git a/libc/cmake/modules/LLVMLibCObjectRules.cmake b/libc/cmake/modules/LLVMLibCObjectRules.cmake
--- a/libc/cmake/modules/LLVMLibCObjectRules.cmake
+++ b/libc/cmake/modules/LLVMLibCObjectRules.cmake
@@ -81,6 +81,10 @@
   )
 
   get_fq_target_name(${target_name} fq_target_name)
+  set(entrypoint_name ${target_name})
+  if(ADD_ENTRYPOINT_OBJ_NAME)
+    set(entrypoint_name ${ADD_ENTRYPOINT_OBJ_NAME})
+  endif()
 
   if(ADD_ENTRYPOINT_OBJ_ALIAS)
     # Alias targets help one add aliases to other entrypoint object targets.
@@ -109,6 +113,7 @@
     set_target_properties(
       ${fq_target_name}
       PROPERTIES
+        "ENTRYPOINT_NAME" ${entrypoint_name}
         "TARGET_TYPE" ${ENTRYPOINT_OBJ_TARGET_TYPE}
         "IS_ALIAS" "YES"
         "OBJECT_FILE" ""
@@ -125,11 +130,6 @@
     message(FATAL_ERROR "`add_entrypoint_object` rule requires HDRS to be specified.")
   endif()
 
-  set(entrypoint_name ${target_name})
-  if(ADD_ENTRYPOINT_OBJ_NAME)
-    set(entrypoint_name ${ADD_ENTRYPOINT_OBJ_NAME})
-  endif()
-
   set(objects_target_name "${fq_target_name}_objects")
 
   add_library(
@@ -199,6 +199,7 @@
   set_target_properties(
     ${fq_target_name}
     PROPERTIES
+      "ENTRYPOINT_NAME" ${entrypoint_name}
       "TARGET_TYPE" ${ENTRYPOINT_OBJ_TARGET_TYPE}
       "OBJECT_FILE" "${object_file}"
       "OBJECT_FILE_RAW" "${object_file_raw}"
@@ -255,7 +256,7 @@
       # crossplatform touch.
       COMMAND "${CMAKE_COMMAND}" -E touch ${lint_timestamp}
       COMMENT "Linting... ${target_name}"
-      DEPENDS ${clang-tidy} ${objects_target_name} ${ADD_ENTRYPOINT_OBJ_SRCS}
+      DEPENDS clang-tidy ${objects_target_name} ${ADD_ENTRYPOINT_OBJ_SRCS}
       WORKING_DIRECTORY ${CMAKE_CURRENT_SOURCE_DIR}
     )
 
diff --git a/libc/lib/CMakeLists.txt b/libc/config/linux/entrypoints.txt
copy from libc/lib/CMakeLists.txt
copy to libc/config/linux/entrypoints.txt
--- a/libc/lib/CMakeLists.txt
+++ b/libc/config/linux/entrypoints.txt
@@ -1,7 +1,4 @@
-
-add_entrypoint_library(
-  llvmlibc
-  DEPENDS
+set(LIBC_ENTRYPOINTS
     # assert.h entrypoints
     libc.src.assert.__assert_fail
 
@@ -23,11 +20,9 @@
     libc.src.stdlib.abort
 
     # string.h entrypoints
-    libc.src.string.bzero
     libc.src.string.memcpy
-    libc.src.string.memset
-    libc.src.string.strcat
     libc.src.string.strcpy
+    libc.src.string.strcat
     libc.src.string.strlen
 
     # sys/mman.h entrypoints
@@ -45,22 +40,10 @@
     libc.src.unistd.write
 )
 
-add_entrypoint_library(
-  llvmlibm
-  DEPENDS
+set(LIBM_ENTRYPOINTS
     # math.h entrypoints
     libc.src.math.cosf
-    libc.src.math.fabs
-    libc.src.math.fabsf
-    libc.src.math.expf
-    libc.src.math.exp2f
     libc.src.math.round
     libc.src.math.sincosf
     libc.src.math.sinf
-)
-
-add_redirector_library(
-  llvmlibc_redirectors
-  DEPENDS
-    round_redirector
-)
+)
\ No newline at end of file
diff --git a/libc/config/linux/headers.txt b/libc/config/linux/headers.txt
new file mode 100644
--- /dev/null
+++ b/libc/config/linux/headers.txt
@@ -0,0 +1,12 @@
+set(PUBLIC_HEADERS
+    libc.include.assert_h
+    libc.include.errno
+    libc.include.math
+    libc.include.signal
+    libc.include.stdio
+    libc.include.stdlib
+    libc.include.sys_mman
+    libc.include.sys_syscall
+    libc.include.threads
+    libc.include.unistd
+)
diff --git a/libc/include/CMakeLists.txt b/libc/include/CMakeLists.txt
--- a/libc/include/CMakeLists.txt
+++ b/libc/include/CMakeLists.txt
@@ -1,4 +1,3 @@
-
 add_header(
   llvm_libc_common_h
   HDR
diff --git a/libc/lib/CMakeLists.txt b/libc/lib/CMakeLists.txt
--- a/libc/lib/CMakeLists.txt
+++ b/libc/lib/CMakeLists.txt
@@ -1,62 +1,16 @@
+include("${LIBC_SOURCE_DIR}/config/${LIBC_TARGET_OS}/entrypoints.txt")
+include("${LIBC_SOURCE_DIR}/config/${LIBC_TARGET_OS}/headers.txt")
 
 add_entrypoint_library(
   llvmlibc
   DEPENDS
-    # assert.h entrypoints
-    libc.src.assert.__assert_fail
-
-    # errno.h entrypoints
-    libc.src.errno.__errno_location
-
-    # signal.h entrypoints
-    libc.src.signal.raise
-    libc.src.signal.sigaction
-    libc.src.signal.sigdelset
-    libc.src.signal.sigaddset
-    libc.src.signal.sigemptyset
-    libc.src.signal.sigprocmask
-    libc.src.signal.sigfillset
-    libc.src.signal.signal
-
-    # stdlib.h entrypoints
-    libc.src.stdlib._Exit
-    libc.src.stdlib.abort
-
-    # string.h entrypoints
-    libc.src.string.bzero
-    libc.src.string.memcpy
-    libc.src.string.memset
-    libc.src.string.strcat
-    libc.src.string.strcpy
-    libc.src.string.strlen
-
-    # sys/mman.h entrypoints
-    libc.src.sys.mman.mmap
-    libc.src.sys.mman.munmap
-
-    # threads.h entrypoints
-    libc.src.threads.mtx_init
-    libc.src.threads.mtx_lock
-    libc.src.threads.mtx_unlock
-    libc.src.threads.thrd_create
-    libc.src.threads.thrd_join
-
-    # unistd.h entrypoints
-    libc.src.unistd.write
+  ${LIBC_ENTRYPOINTS}
 )
 
 add_entrypoint_library(
   llvmlibm
   DEPENDS
-    # math.h entrypoints
-    libc.src.math.cosf
-    libc.src.math.fabs
-    libc.src.math.fabsf
-    libc.src.math.expf
-    libc.src.math.exp2f
-    libc.src.math.round
-    libc.src.math.sincosf
-    libc.src.math.sinf
+  ${LIBM_ENTRYPOINTS}
 )
 
 add_redirector_library(
@@ -64,3 +18,12 @@
   DEPENDS
     round_redirector
 )
+
+add_libc_public_integration_test(
+  public_integration_test
+  LIBS
+    llvmlibc
+    llvmlibm
+  PUBLIC_HDRS
+    ${PUBLIC_HEADERS}
+)
diff --git a/libc/utils/HdrGen/CMakeLists.txt b/libc/utils/HdrGen/CMakeLists.txt
--- a/libc/utils/HdrGen/CMakeLists.txt
+++ b/libc/utils/HdrGen/CMakeLists.txt
@@ -11,3 +11,5 @@
   PublicAPICommand.cpp
   PublicAPICommand.h
 )
+
+add_subdirectory(PrototypeTestGen)
diff --git a/libc/utils/HdrGen/PrototypeTestGen/CMakeLists.txt b/libc/utils/HdrGen/PrototypeTestGen/CMakeLists.txt
new file mode 100644
--- /dev/null
+++ b/libc/utils/HdrGen/PrototypeTestGen/CMakeLists.txt
@@ -0,0 +1,5 @@
+add_tablegen(libc-prototype-testgen llvm-libc
+  PrototypeTestGen.cpp
+  ../PublicAPICommand.cpp
+  ../Command.cpp
+)
diff --git a/libc/utils/HdrGen/PrototypeTestGen/PrototypeTestGen.cpp b/libc/utils/HdrGen/PrototypeTestGen/PrototypeTestGen.cpp
new file mode 100644
--- /dev/null
+++ b/libc/utils/HdrGen/PrototypeTestGen/PrototypeTestGen.cpp
@@ -0,0 +1,71 @@
+//===-- PrototypeTestGen.cpp ----------------------------------------------===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+
+#include "../PublicAPICommand.h"
+
+#include "llvm/ADT/StringRef.h"
+#include "llvm/Support/CommandLine.h"
+#include "llvm/TableGen/Main.h"
+#include "llvm/TableGen/Record.h"
+
+namespace {
+
+llvm::cl::list<std::string>
+    EntrypointNamesOption("e", llvm::cl::desc("<list of entrypoints>"),
+                          llvm::cl::OneOrMore);
+
+} // anonymous namespace
+
+bool TestGeneratorMain(llvm::raw_ostream &OS, llvm::RecordKeeper &records) {
+  OS << "#include \"TypeTraits.h\"\n";
+  auto G = llvm_libc::makeAPIReader(records);
+  for (const auto &header : G->PublicHeaders)
+    OS << "#include <" << header << ">\n";
+  OS << '\n';
+  OS << "int main() {\n";
+  for (const auto &entrypoint : EntrypointNamesOption) {
+    auto match = G->FunctionSpecMap.find(entrypoint);
+    if (match == G->FunctionSpecMap.end()) {
+      llvm::errs() << "ERROR: entrypoint '" << entrypoint
+                   << "' could not be found in spec in any public header\n";
+      return true;
+    }
+    llvm::Record *functionSpec = match->second;
+    llvm::Record *retValSpec = functionSpec->getValueAsDef("Return");
+    llvm::StringRef returnType =
+        G->getTypeAsString(retValSpec->getValueAsDef("ReturnType"));
+    // _Noreturn is an indication for the compiler that a function
+    // doesn't return, and isn't a type understood by c++ templates.
+    if (returnType.contains("_Noreturn"))
+      returnType = "void";
+
+    OS << "  static_assert(__llvm_libc::cpp::IsSame<" << returnType << '(';
+    auto args = functionSpec->getValueAsListOfDefs("Args");
+    for (size_t i = 0, size = args.size(); i < size; ++i) {
+      llvm::Record *argType = args[i]->getValueAsDef("ArgType");
+      OS << G->getTypeAsString(argType);
+      if (i < size - 1)
+        OS << ", ";
+    }
+    OS << "), decltype(" << entrypoint << ")>::Value, ";
+    OS << '"' << entrypoint
+       << " prototype in TableGen does not match public header" << '"';
+    OS << ");\n";
+  }
+
+  OS << '\n';
+  OS << "  return 0;\n";
+  OS << "}\n\n";
+
+  return false;
+}
+
+int main(int argc, char *argv[]) {
+  llvm::cl::ParseCommandLineOptions(argc, argv);
+  return TableGenMain(argv[0], TestGeneratorMain);
+}
diff --git a/libc/utils/HdrGen/PublicAPICommand.h b/libc/utils/HdrGen/PublicAPICommand.h
--- a/libc/utils/HdrGen/PublicAPICommand.h
+++ b/libc/utils/HdrGen/PublicAPICommand.h
@@ -25,6 +25,9 @@
 
 } // namespace llvm
 
+using NameToRecordMapping = std::unordered_map<std::string, llvm::Record *>;
+using NameSet = std::unordered_set<std::string>;
+
 namespace llvm_libc {
 
 class PublicAPICommand : public Command {
@@ -36,6 +39,28 @@
            const Command::ErrorReporter &Reporter) const override;
 };
 
+class APIReader {
+public:
+  // 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;
+
+  virtual std::string getTypeAsString(llvm::Record *TypeRecord) = 0;
+
+  virtual ~APIReader() {}
+};
+
+std::unique_ptr<APIReader> makeAPIReader(llvm::RecordKeeper &Records);
+
 } // namespace llvm_libc
 
 #endif // LLVM_LIBC_UTILS_HDRGEN_PUBLICAPICOMMAND_H
diff --git a/libc/utils/HdrGen/PublicAPICommand.cpp b/libc/utils/HdrGen/PublicAPICommand.cpp
--- a/libc/utils/HdrGen/PublicAPICommand.cpp
+++ b/libc/utils/HdrGen/PublicAPICommand.cpp
@@ -57,8 +57,8 @@
   }
 }
 
-class APIGenerator {
-  llvm::StringRef StdHeader;
+class APIGenerator : public llvm_libc::APIReader {
+  llvm::Optional<llvm::StringRef> StdHeader;
 
   // TableGen classes in spec.td.
   llvm::Record *NamedTypeClass;
@@ -69,21 +69,6 @@
   llvm::Record *StandardSpecClass;
   llvm::Record *PublicAPIClass;
 
-  using NameToRecordMapping = std::unordered_map<std::string, llvm::Record *>;
-  using NameSet = std::unordered_set<std::string>;
-
-  // 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;
-
   bool isaNamedType(llvm::Record *Def) { return isa(Def, NamedTypeClass); }
 
   bool isaStructType(llvm::Record *Def) { return isa(Def, StructClass); }
@@ -102,7 +87,7 @@
 
   bool isaPublicAPI(llvm::Record *Def) { return isa(Def, PublicAPIClass); }
 
-  std::string getTypeAsString(llvm::Record *TypeRecord) {
+  std::string getTypeAsString(llvm::Record *TypeRecord) override {
     if (isaNamedType(TypeRecord) || isaStructType(TypeRecord)) {
       return std::string(TypeRecord->getValueAsString("Name"));
     } else if (isaPtrType(TypeRecord)) {
@@ -121,7 +106,9 @@
   void indexStandardSpecDef(llvm::Record *StandardSpec) {
     auto HeaderSpecList = StandardSpec->getValueAsListOfDefs("Headers");
     for (llvm::Record *HeaderSpec : HeaderSpecList) {
-      if (HeaderSpec->getValueAsString("Name") == StdHeader) {
+      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)
@@ -189,13 +176,17 @@
       if (isaStandardSpec(Def))
         indexStandardSpecDef(Def);
       if (isaPublicAPI(Def)) {
-        if (Def->getValueAsString("HeaderName") == StdHeader)
+        if (!StdHeader.hasValue() ||
+            Def->getValueAsString("HeaderName") == StdHeader)
           indexPublicAPIDef(Def);
       }
     }
   }
 
 public:
+  explicit APIGenerator(llvm::RecordKeeper &Records) : StdHeader(llvm::None) {
+    index(Records);
+  }
   APIGenerator(llvm::StringRef Header, llvm::RecordKeeper &Records)
       : StdHeader(Header) {
     index(Records);
@@ -286,4 +277,8 @@
   G.write(OS);
 }
 
+std::unique_ptr<APIReader> makeAPIReader(llvm::RecordKeeper &Records) {
+  return std::make_unique<APIGenerator>(Records);
+}
+
 } // namespace llvm_libc