diff --git a/toolchain/base/clang_invocation.cpp b/toolchain/base/clang_invocation.cpp
index b34d43f70db1..1677c5a9d0a1 100644
--- a/toolchain/base/clang_invocation.cpp
+++ b/toolchain/base/clang_invocation.cpp
@@ -118,6 +118,13 @@ auto AppendDefaultClangArgs(const InstallPaths& install_paths,
       // TODO: Decide if we want this.
       "-fPIE",
 
+      // Enable function and data sections by default, and don't waste object
+      // file size on unique section names. Allow these to be overridden by
+      // Clang arguments.
+      "-ffunction-sections",
+      "-fdata-sections",
+      "-fno-unique-section-names",
+
       // Override runtime library defaults.
       //
       // TODO: We should consider if there is a reasonable way to build Clang
diff --git a/toolchain/driver/compile_subcommand.cpp b/toolchain/driver/compile_subcommand.cpp
index 26fe55a229cb..9467f9e6b41c 100644
--- a/toolchain/driver/compile_subcommand.cpp
+++ b/toolchain/driver/compile_subcommand.cpp
@@ -492,7 +492,7 @@ class CompilationUnit {
   auto RunLower() -> void;
 
   // Runs the optimization pipeline.
-  auto RunOptimize() -> void;
+  auto RunOptimize(const clang::CompilerInvocation& clang_invocation) -> void;
 
   // Runs post-lowering-to-LLVM-IR logic. This is always called if we do any
   // lowering work, after we've finished building the IR in RunLower() and,
@@ -538,7 +538,8 @@ class CompilationUnit {
   auto IncludeInDumps() -> bool;
 
   // Builds the LLVM target machine.
-  auto MakeTargetMachine() -> void;
+  auto MakeTargetMachine(const clang::CompilerInvocation& clang_invocation)
+      -> void;
 
   // The index of the unit amongst all units.
   SemIR::CheckIRId check_ir_id_;
@@ -814,7 +815,8 @@ auto CompilationUnit::RunLower() -> void {
   });
 }
 
-auto CompilationUnit::MakeTargetMachine() -> void {
+auto CompilationUnit::MakeTargetMachine(
+    const clang::CompilerInvocation& clang_invocation) -> void {
   CARBON_CHECK(module_, "Must call RunLower first");
   CARBON_CHECK(!target_machine_, "Should not call this multiple times");
 
@@ -828,7 +830,16 @@ auto CompilationUnit::MakeTargetMachine() -> void {
   constexpr llvm::StringLiteral CPU = "generic";
   constexpr llvm::StringLiteral Features = "";
 
+  const auto& codegen_opts = clang_invocation.getCodeGenOpts();
+
+  // TODO: Make the code in Clang's BackendUtil.cpp externally accessible and
+  // call it from here. This is doing a subset of the same work to translate
+  // Clang code generation options into target options.
   llvm::TargetOptions target_opts;
+  target_opts.UseInitArray = codegen_opts.UseInitArray;
+  target_opts.FunctionSections = codegen_opts.FunctionSections;
+  target_opts.DataSections = codegen_opts.DataSections;
+  target_opts.UniqueSectionNames = codegen_opts.UniqueSectionNames;
   target_machine_.reset(target_->createTargetMachine(
       target_triple, CPU, Features, target_opts, llvm::Reloc::PIC_));
 }
@@ -863,7 +874,8 @@ static auto GetClangOptimizationFlag(Lower::OptimizationLevel opt_level)
   }
 }
 
-auto CompilationUnit::RunOptimize() -> void {
+auto CompilationUnit::RunOptimize(
+    const clang::CompilerInvocation& clang_invocation) -> void {
   CARBON_CHECK(module_, "Must call RunLower first");
 
   // TODO: A lot of the work done here duplicates work done by Clang setting up
@@ -873,7 +885,7 @@ auto CompilationUnit::RunOptimize() -> void {
   // pipeline rather than building one of our own, or factoring out enough of
   // Clang's pipeline builder that we can reuse and further customize it.
 
-  MakeTargetMachine();
+  MakeTargetMachine(clang_invocation);
 
   // TODO: There's no way to set these automatically from an
   // llvm::OptimizationLevel. Add such a mechanism to LLVM and use it from
@@ -1094,7 +1106,9 @@ auto CompileSubcommand::Run(DriverEnv& driver_env) -> DriverResult {
   // Build a clang invocation. We do this regardless of whether we're running
   // check, because this is essentially performing further option validation,
   // and we generally validate all options even if we're not using them for the
-  // selected phases of compilation.
+  // selected phases of compilation. We also use Clang's target option handling
+  // to configure our target, to ensure that we are using the same ABI for both
+  // the C++ and Carbon parts of the compilation.
   // TODO: Share any arguments we specify here with the `carbon clang`
   // subcommand.
   {
@@ -1283,7 +1297,7 @@ auto CompileSubcommand::Run(DriverEnv& driver_env) -> DriverResult {
     unit->RunLower();
 
     if (options_.phase != CompileOptions::Phase::Lower) {
-      unit->RunOptimize();
+      unit->RunOptimize(*clang_invocation);
     }
 
     unit->PostLower();
diff --git a/toolchain/driver/testdata/compile/init_array.carbon b/toolchain/driver/testdata/compile/init_array.carbon
new file mode 100644
index 000000000000..76ee574803ca
--- /dev/null
+++ b/toolchain/driver/testdata/compile/init_array.carbon
@@ -0,0 +1,24 @@
+// Part of the Carbon Language project, under the Apache License v2.0 with LLVM
+// Exceptions. See /LICENSE for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+// ARGS: compile foo.carbon --asm-output --output=- --target=x86_64-linux-gnu
+//
+// NOAUTOUPDATE
+// SET-CHECK-SUBSET
+// TIP: To test this file alone, run:
+// TIP:   bazel test //toolchain/testing:file_test --test_arg=--file_tests=toolchain/driver/testdata/compile/target_machine.carbon
+// TIP: To dump output, run:
+// TIP:   bazel run //toolchain/testing:file_test -- --dump_output --file_tests=toolchain/driver/testdata/compile/target_machine.carbon
+
+// --- foo.carbon
+
+import Cpp inline '''
+int f();
+inline int n = f();
+''';
+
+// We should use init_array, overriding LLVM's default of using ctors, as Clang
+// does.
+// CHECK:STDOUT: {{\s*}}.section{{\s+}}.init_array,{{.*}}
+// CHECK:STDOUT: {{\s*}}.quad{{\s+}}__cxx_global_var_init
diff --git a/toolchain/driver/testdata/compile/no_init_array.carbon b/toolchain/driver/testdata/compile/no_init_array.carbon
new file mode 100644
index 000000000000..6107c01e9f8e
--- /dev/null
+++ b/toolchain/driver/testdata/compile/no_init_array.carbon
@@ -0,0 +1,23 @@
+// Part of the Carbon Language project, under the Apache License v2.0 with LLVM
+// Exceptions. See /LICENSE for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+// ARGS: compile foo.carbon --asm-output --output=- --target=x86_64-linux-gnu -- -fno-use-init-array
+//
+// NOAUTOUPDATE
+// SET-CHECK-SUBSET
+// TIP: To test this file alone, run:
+// TIP:   bazel test //toolchain/testing:file_test --test_arg=--file_tests=toolchain/driver/testdata/compile/target_machine.carbon
+// TIP: To dump output, run:
+// TIP:   bazel run //toolchain/testing:file_test -- --dump_output --file_tests=toolchain/driver/testdata/compile/target_machine.carbon
+
+// --- foo.carbon
+
+import Cpp inline '''
+int f();
+inline int n = f();
+''';
+
+// We should not use init_array, following the command-line flag.
+// CHECK:STDOUT: {{\s*}}.section{{\s+}}.ctors,{{.*}}
+// CHECK:STDOUT: {{\s*}}.quad{{\s+}}__cxx_global_var_init