diff --git a/compiler/rustc_codegen_gcc/src/back/lto.rs b/compiler/rustc_codegen_gcc/src/back/lto.rs
index d558dfbc1c455..fcee6b6df6234 100644
--- a/compiler/rustc_codegen_gcc/src/back/lto.rs
+++ b/compiler/rustc_codegen_gcc/src/back/lto.rs
@@ -29,7 +29,7 @@ use rustc_codegen_ssa::back::write::{CodegenContext, FatLtoInput};
 use rustc_codegen_ssa::traits::*;
 use rustc_codegen_ssa::{ModuleCodegen, ModuleKind, looks_like_rust_object_file};
 use rustc_data_structures::memmap::Mmap;
-use rustc_errors::{DiagCtxtHandle, FatalError};
+use rustc_errors::DiagCtxtHandle;
 use rustc_middle::bug;
 use rustc_middle::dep_graph::WorkProduct;
 use rustc_session::config::Lto;
@@ -51,12 +51,11 @@ fn prepare_lto(
     cgcx: &CodegenContext<GccCodegenBackend>,
     each_linked_rlib_for_lto: &[PathBuf],
     dcx: DiagCtxtHandle<'_>,
-) -> Result<LtoData, FatalError> {
+) -> LtoData {
     let tmp_path = match tempdir() {
         Ok(tmp_path) => tmp_path,
         Err(error) => {
-            eprintln!("Cannot create temporary directory: {}", error);
-            return Err(FatalError);
+            dcx.fatal(format!("Cannot create temporary directory: {}", error));
         }
     };
 
@@ -91,15 +90,14 @@ fn prepare_lto(
                         upstream_modules.push((module, CString::new(name).unwrap()));
                     }
                     Err(e) => {
-                        dcx.emit_err(e);
-                        return Err(FatalError);
+                        dcx.emit_fatal(e);
                     }
                 }
             }
         }
     }
 
-    Ok(LtoData { upstream_modules, tmp_path })
+    LtoData { upstream_modules, tmp_path }
 }
 
 fn save_as_file(obj: &[u8], path: &Path) -> Result<(), LtoBitcodeFromRlib> {
@@ -114,10 +112,10 @@ pub(crate) fn run_fat(
     cgcx: &CodegenContext<GccCodegenBackend>,
     each_linked_rlib_for_lto: &[PathBuf],
     modules: Vec<FatLtoInput<GccCodegenBackend>>,
-) -> Result<ModuleCodegen<GccContext>, FatalError> {
+) -> ModuleCodegen<GccContext> {
     let dcx = cgcx.create_dcx();
     let dcx = dcx.handle();
-    let lto_data = prepare_lto(cgcx, each_linked_rlib_for_lto, dcx)?;
+    let lto_data = prepare_lto(cgcx, each_linked_rlib_for_lto, dcx);
     /*let symbols_below_threshold =
     lto_data.symbols_below_threshold.iter().map(|c| c.as_ptr()).collect::<Vec<_>>();*/
     fat_lto(
@@ -137,7 +135,7 @@ fn fat_lto(
     mut serialized_modules: Vec<(SerializedModule<ModuleBuffer>, CString)>,
     tmp_path: TempDir,
     //symbols_below_threshold: &[String],
-) -> Result<ModuleCodegen<GccContext>, FatalError> {
+) -> ModuleCodegen<GccContext> {
     let _timer = cgcx.prof.generic_activity("GCC_fat_lto_build_monolithic_module");
     info!("going for a fat lto");
 
@@ -261,7 +259,7 @@ fn fat_lto(
     // of now.
     module.module_llvm.temp_dir = Some(tmp_path);
 
-    Ok(module)
+    module
 }
 
 pub struct ModuleBuffer(PathBuf);
@@ -286,10 +284,10 @@ pub(crate) fn run_thin(
     each_linked_rlib_for_lto: &[PathBuf],
     modules: Vec<(String, ThinBuffer)>,
     cached_modules: Vec<(SerializedModule<ModuleBuffer>, WorkProduct)>,
-) -> Result<(Vec<ThinModule<GccCodegenBackend>>, Vec<WorkProduct>), FatalError> {
+) -> (Vec<ThinModule<GccCodegenBackend>>, Vec<WorkProduct>) {
     let dcx = cgcx.create_dcx();
     let dcx = dcx.handle();
-    let lto_data = prepare_lto(cgcx, each_linked_rlib_for_lto, dcx)?;
+    let lto_data = prepare_lto(cgcx, each_linked_rlib_for_lto, dcx);
     if cgcx.opts.cg.linker_plugin_lto.enabled() {
         unreachable!(
             "We should never reach this case if the LTO step \
@@ -355,7 +353,7 @@ fn thin_lto(
     tmp_path: TempDir,
     cached_modules: Vec<(SerializedModule<ModuleBuffer>, WorkProduct)>,
     //_symbols_below_threshold: &[String],
-) -> Result<(Vec<ThinModule<GccCodegenBackend>>, Vec<WorkProduct>), FatalError> {
+) -> (Vec<ThinModule<GccCodegenBackend>>, Vec<WorkProduct>) {
     let _timer = cgcx.prof.generic_activity("LLVM_thin_lto_global_analysis");
     info!("going for that thin, thin LTO");
 
@@ -518,13 +516,13 @@ fn thin_lto(
     // TODO: save the directory so that it gets deleted later.
     std::mem::forget(tmp_path);
 
-    Ok((opt_jobs, copy_jobs))
+    (opt_jobs, copy_jobs)
 }
 
 pub fn optimize_thin_module(
     thin_module: ThinModule<GccCodegenBackend>,
     _cgcx: &CodegenContext<GccCodegenBackend>,
-) -> Result<ModuleCodegen<GccContext>, FatalError> {
+) -> ModuleCodegen<GccContext> {
     //let dcx = cgcx.create_dcx();
 
     //let module_name = &thin_module.shared.module_names[thin_module.idx];
@@ -634,7 +632,8 @@ pub fn optimize_thin_module(
             save_temp_bitcode(cgcx, &module, "thin-lto-after-pm");
         }
     }*/
-    Ok(module)
+    #[allow(clippy::let_and_return)]
+    module
 }
 
 pub struct ThinBuffer {
diff --git a/compiler/rustc_codegen_gcc/src/back/write.rs b/compiler/rustc_codegen_gcc/src/back/write.rs
index c1231142c6585..84bc70162719f 100644
--- a/compiler/rustc_codegen_gcc/src/back/write.rs
+++ b/compiler/rustc_codegen_gcc/src/back/write.rs
@@ -6,7 +6,6 @@ use rustc_codegen_ssa::back::write::{BitcodeSection, CodegenContext, EmitObj, Mo
 use rustc_codegen_ssa::{CompiledModule, ModuleCodegen};
 use rustc_fs_util::link_or_copy;
 use rustc_session::config::OutputType;
-use rustc_span::fatal_error::FatalError;
 use rustc_target::spec::SplitDebuginfo;
 
 use crate::base::add_pic_option;
@@ -17,7 +16,7 @@ pub(crate) fn codegen(
     cgcx: &CodegenContext<GccCodegenBackend>,
     module: ModuleCodegen<GccContext>,
     config: &ModuleConfig,
-) -> Result<CompiledModule, FatalError> {
+) -> CompiledModule {
     let dcx = cgcx.create_dcx();
     let dcx = dcx.handle();
 
@@ -246,7 +245,7 @@ pub(crate) fn codegen(
         }
     }
 
-    Ok(module.into_compiled_module(
+    module.into_compiled_module(
         config.emit_obj != EmitObj::None,
         cgcx.target_can_use_split_dwarf && cgcx.split_debuginfo == SplitDebuginfo::Unpacked,
         config.emit_bc,
@@ -254,7 +253,7 @@ pub(crate) fn codegen(
         config.emit_ir,
         &cgcx.output_filenames,
         cgcx.invocation_temp.as_deref(),
-    ))
+    )
 }
 
 pub(crate) fn save_temp_bitcode(
diff --git a/compiler/rustc_codegen_gcc/src/lib.rs b/compiler/rustc_codegen_gcc/src/lib.rs
index 4025aba82da32..2d7df79ba95fa 100644
--- a/compiler/rustc_codegen_gcc/src/lib.rs
+++ b/compiler/rustc_codegen_gcc/src/lib.rs
@@ -110,7 +110,6 @@ use rustc_middle::util::Providers;
 use rustc_session::Session;
 use rustc_session::config::{OptLevel, OutputFilenames};
 use rustc_span::Symbol;
-use rustc_span::fatal_error::FatalError;
 use rustc_target::spec::RelocModel;
 use tempfile::TempDir;
 
@@ -362,7 +361,7 @@ impl WriteBackendMethods for GccCodegenBackend {
         _exported_symbols_for_lto: &[String],
         each_linked_rlib_for_lto: &[PathBuf],
         modules: Vec<FatLtoInput<Self>>,
-    ) -> Result<ModuleCodegen<Self::Module>, FatalError> {
+    ) -> ModuleCodegen<Self::Module> {
         back::lto::run_fat(cgcx, each_linked_rlib_for_lto, modules)
     }
 
@@ -373,7 +372,7 @@ impl WriteBackendMethods for GccCodegenBackend {
         each_linked_rlib_for_lto: &[PathBuf],
         modules: Vec<(String, Self::ThinBuffer)>,
         cached_modules: Vec<(SerializedModule<Self::ModuleBuffer>, WorkProduct)>,
-    ) -> Result<(Vec<ThinModule<Self>>, Vec<WorkProduct>), FatalError> {
+    ) -> (Vec<ThinModule<Self>>, Vec<WorkProduct>) {
         back::lto::run_thin(cgcx, each_linked_rlib_for_lto, modules, cached_modules)
     }
 
@@ -390,15 +389,14 @@ impl WriteBackendMethods for GccCodegenBackend {
         _dcx: DiagCtxtHandle<'_>,
         module: &mut ModuleCodegen<Self::Module>,
         config: &ModuleConfig,
-    ) -> Result<(), FatalError> {
+    ) {
         module.module_llvm.context.set_optimization_level(to_gcc_opt_level(config.opt_level));
-        Ok(())
     }
 
     fn optimize_thin(
         cgcx: &CodegenContext<Self>,
         thin: ThinModule<Self>,
-    ) -> Result<ModuleCodegen<Self::Module>, FatalError> {
+    ) -> ModuleCodegen<Self::Module> {
         back::lto::optimize_thin_module(thin, cgcx)
     }
 
@@ -406,7 +404,7 @@ impl WriteBackendMethods for GccCodegenBackend {
         cgcx: &CodegenContext<Self>,
         module: ModuleCodegen<Self::Module>,
         config: &ModuleConfig,
-    ) -> Result<CompiledModule, FatalError> {
+    ) -> CompiledModule {
         back::write::codegen(cgcx, module, config)
     }
 
diff --git a/compiler/rustc_codegen_llvm/src/back/lto.rs b/compiler/rustc_codegen_llvm/src/back/lto.rs
index 853d0295238e6..d85f432702cc5 100644
--- a/compiler/rustc_codegen_llvm/src/back/lto.rs
+++ b/compiler/rustc_codegen_llvm/src/back/lto.rs
@@ -14,7 +14,7 @@ use rustc_codegen_ssa::traits::*;
 use rustc_codegen_ssa::{ModuleCodegen, ModuleKind, looks_like_rust_object_file};
 use rustc_data_structures::fx::FxHashMap;
 use rustc_data_structures::memmap::Mmap;
-use rustc_errors::{DiagCtxtHandle, FatalError};
+use rustc_errors::DiagCtxtHandle;
 use rustc_middle::bug;
 use rustc_middle::dep_graph::WorkProduct;
 use rustc_session::config::{self, Lto};
@@ -36,7 +36,7 @@ fn prepare_lto(
     exported_symbols_for_lto: &[String],
     each_linked_rlib_for_lto: &[PathBuf],
     dcx: DiagCtxtHandle<'_>,
-) -> Result<(Vec<CString>, Vec<(SerializedModule<ModuleBuffer>, CString)>), FatalError> {
+) -> (Vec<CString>, Vec<(SerializedModule<ModuleBuffer>, CString)>) {
     let mut symbols_below_threshold = exported_symbols_for_lto
         .iter()
         .map(|symbol| CString::new(symbol.to_owned()).unwrap())
@@ -79,16 +79,13 @@ fn prepare_lto(
                         let module = SerializedModule::FromRlib(data.to_vec());
                         upstream_modules.push((module, CString::new(name).unwrap()));
                     }
-                    Err(e) => {
-                        dcx.emit_err(e);
-                        return Err(FatalError);
-                    }
+                    Err(e) => dcx.emit_fatal(e),
                 }
             }
         }
     }
 
-    Ok((symbols_below_threshold, upstream_modules))
+    (symbols_below_threshold, upstream_modules)
 }
 
 fn get_bitcode_slice_from_object_data<'a>(
@@ -123,11 +120,11 @@ pub(crate) fn run_fat(
     exported_symbols_for_lto: &[String],
     each_linked_rlib_for_lto: &[PathBuf],
     modules: Vec<FatLtoInput<LlvmCodegenBackend>>,
-) -> Result<ModuleCodegen<ModuleLlvm>, FatalError> {
+) -> ModuleCodegen<ModuleLlvm> {
     let dcx = cgcx.create_dcx();
     let dcx = dcx.handle();
     let (symbols_below_threshold, upstream_modules) =
-        prepare_lto(cgcx, exported_symbols_for_lto, each_linked_rlib_for_lto, dcx)?;
+        prepare_lto(cgcx, exported_symbols_for_lto, each_linked_rlib_for_lto, dcx);
     let symbols_below_threshold =
         symbols_below_threshold.iter().map(|c| c.as_ptr()).collect::<Vec<_>>();
     fat_lto(cgcx, dcx, modules, upstream_modules, &symbols_below_threshold)
@@ -142,11 +139,11 @@ pub(crate) fn run_thin(
     each_linked_rlib_for_lto: &[PathBuf],
     modules: Vec<(String, ThinBuffer)>,
     cached_modules: Vec<(SerializedModule<ModuleBuffer>, WorkProduct)>,
-) -> Result<(Vec<ThinModule<LlvmCodegenBackend>>, Vec<WorkProduct>), FatalError> {
+) -> (Vec<ThinModule<LlvmCodegenBackend>>, Vec<WorkProduct>) {
     let dcx = cgcx.create_dcx();
     let dcx = dcx.handle();
     let (symbols_below_threshold, upstream_modules) =
-        prepare_lto(cgcx, exported_symbols_for_lto, each_linked_rlib_for_lto, dcx)?;
+        prepare_lto(cgcx, exported_symbols_for_lto, each_linked_rlib_for_lto, dcx);
     let symbols_below_threshold =
         symbols_below_threshold.iter().map(|c| c.as_ptr()).collect::<Vec<_>>();
     if cgcx.opts.cg.linker_plugin_lto.enabled() {
@@ -173,7 +170,7 @@ fn fat_lto(
     modules: Vec<FatLtoInput<LlvmCodegenBackend>>,
     mut serialized_modules: Vec<(SerializedModule<ModuleBuffer>, CString)>,
     symbols_below_threshold: &[*const libc::c_char],
-) -> Result<ModuleCodegen<ModuleLlvm>, FatalError> {
+) -> ModuleCodegen<ModuleLlvm> {
     let _timer = cgcx.prof.generic_activity("LLVM_fat_lto_build_monolithic_module");
     info!("going for a fat lto");
 
@@ -224,7 +221,7 @@ fn fat_lto(
             assert!(!serialized_modules.is_empty(), "must have at least one serialized module");
             let (buffer, name) = serialized_modules.remove(0);
             info!("no in-memory regular modules to choose from, parsing {:?}", name);
-            let llvm_module = ModuleLlvm::parse(cgcx, &name, buffer.data(), dcx)?;
+            let llvm_module = ModuleLlvm::parse(cgcx, &name, buffer.data(), dcx);
             ModuleCodegen::new_regular(name.into_string().unwrap(), llvm_module)
         }
     };
@@ -265,7 +262,9 @@ fn fat_lto(
                 });
             info!("linking {:?}", name);
             let data = bc_decoded.data();
-            linker.add(data).map_err(|()| write::llvm_err(dcx, LlvmError::LoadBitcode { name }))?;
+            linker
+                .add(data)
+                .unwrap_or_else(|()| write::llvm_err(dcx, LlvmError::LoadBitcode { name }));
         }
         drop(linker);
         save_temp_bitcode(cgcx, &module, "lto.input");
@@ -282,7 +281,7 @@ fn fat_lto(
         save_temp_bitcode(cgcx, &module, "lto.after-restriction");
     }
 
-    Ok(module)
+    module
 }
 
 pub(crate) struct Linker<'a>(&'a mut llvm::Linker<'a>);
@@ -352,7 +351,7 @@ fn thin_lto(
     serialized_modules: Vec<(SerializedModule<ModuleBuffer>, CString)>,
     cached_modules: Vec<(SerializedModule<ModuleBuffer>, WorkProduct)>,
     symbols_below_threshold: &[*const libc::c_char],
-) -> Result<(Vec<ThinModule<LlvmCodegenBackend>>, Vec<WorkProduct>), FatalError> {
+) -> (Vec<ThinModule<LlvmCodegenBackend>>, Vec<WorkProduct>) {
     let _timer = cgcx.prof.generic_activity("LLVM_thin_lto_global_analysis");
     unsafe {
         info!("going for that thin, thin LTO");
@@ -422,7 +421,7 @@ fn thin_lto(
             symbols_below_threshold.as_ptr(),
             symbols_below_threshold.len(),
         )
-        .ok_or_else(|| write::llvm_err(dcx, LlvmError::PrepareThinLtoContext))?;
+        .unwrap_or_else(|| write::llvm_err(dcx, LlvmError::PrepareThinLtoContext));
 
         let data = ThinData(data);
 
@@ -492,10 +491,10 @@ fn thin_lto(
         if let Some(path) = key_map_path
             && let Err(err) = curr_key_map.save_to_file(&path)
         {
-            return Err(write::llvm_err(dcx, LlvmError::WriteThinLtoKey { err }));
+            write::llvm_err(dcx, LlvmError::WriteThinLtoKey { err });
         }
 
-        Ok((opt_jobs, copy_jobs))
+        (opt_jobs, copy_jobs)
     }
 }
 
@@ -550,7 +549,7 @@ pub(crate) fn run_pass_manager(
     dcx: DiagCtxtHandle<'_>,
     module: &mut ModuleCodegen<ModuleLlvm>,
     thin: bool,
-) -> Result<(), FatalError> {
+) {
     let _timer = cgcx.prof.generic_activity_with_arg("LLVM_lto_optimize", &*module.name);
     let config = cgcx.config(module.kind);
 
@@ -582,7 +581,7 @@ pub(crate) fn run_pass_manager(
     }
 
     unsafe {
-        write::llvm_optimize(cgcx, dcx, module, None, config, opt_level, opt_stage, stage)?;
+        write::llvm_optimize(cgcx, dcx, module, None, config, opt_level, opt_stage, stage);
     }
 
     if enable_gpu && !thin {
@@ -596,7 +595,7 @@ pub(crate) fn run_pass_manager(
         let stage = write::AutodiffStage::PostAD;
         if !config.autodiff.contains(&config::AutoDiff::NoPostopt) {
             unsafe {
-                write::llvm_optimize(cgcx, dcx, module, None, config, opt_level, opt_stage, stage)?;
+                write::llvm_optimize(cgcx, dcx, module, None, config, opt_level, opt_stage, stage);
             }
         }
 
@@ -608,7 +607,6 @@ pub(crate) fn run_pass_manager(
     }
 
     debug!("lto done");
-    Ok(())
 }
 
 pub struct ModuleBuffer(&'static mut llvm::ModuleBuffer);
@@ -701,7 +699,7 @@ impl Drop for ThinBuffer {
 pub(crate) fn optimize_thin_module(
     thin_module: ThinModule<LlvmCodegenBackend>,
     cgcx: &CodegenContext<LlvmCodegenBackend>,
-) -> Result<ModuleCodegen<ModuleLlvm>, FatalError> {
+) -> ModuleCodegen<ModuleLlvm> {
     let dcx = cgcx.create_dcx();
     let dcx = dcx.handle();
 
@@ -712,7 +710,7 @@ pub(crate) fn optimize_thin_module(
     // into that context. One day, however, we may do this for upstream
     // crates but for locally codegened modules we may be able to reuse
     // that LLVM Context and Module.
-    let module_llvm = ModuleLlvm::parse(cgcx, module_name, thin_module.data(), dcx)?;
+    let module_llvm = ModuleLlvm::parse(cgcx, module_name, thin_module.data(), dcx);
     let mut module = ModuleCodegen::new_regular(thin_module.name(), module_llvm);
     // Given that the newly created module lacks a thinlto buffer for embedding, we need to re-add it here.
     if cgcx.config(ModuleKind::Regular).embed_bitcode() {
@@ -746,7 +744,7 @@ pub(crate) fn optimize_thin_module(
                 .generic_activity_with_arg("LLVM_thin_lto_resolve_weak", thin_module.name());
             if unsafe { !llvm::LLVMRustPrepareThinLTOResolveWeak(thin_module.shared.data.0, llmod) }
             {
-                return Err(write::llvm_err(dcx, LlvmError::PrepareThinLtoModule));
+                write::llvm_err(dcx, LlvmError::PrepareThinLtoModule);
             }
             save_temp_bitcode(cgcx, &module, "thin-lto-after-resolve");
         }
@@ -757,7 +755,7 @@ pub(crate) fn optimize_thin_module(
                 .generic_activity_with_arg("LLVM_thin_lto_internalize", thin_module.name());
             if unsafe { !llvm::LLVMRustPrepareThinLTOInternalize(thin_module.shared.data.0, llmod) }
             {
-                return Err(write::llvm_err(dcx, LlvmError::PrepareThinLtoModule));
+                write::llvm_err(dcx, LlvmError::PrepareThinLtoModule);
             }
             save_temp_bitcode(cgcx, &module, "thin-lto-after-internalize");
         }
@@ -768,7 +766,7 @@ pub(crate) fn optimize_thin_module(
             if unsafe {
                 !llvm::LLVMRustPrepareThinLTOImport(thin_module.shared.data.0, llmod, target.raw())
             } {
-                return Err(write::llvm_err(dcx, LlvmError::PrepareThinLtoModule));
+                write::llvm_err(dcx, LlvmError::PrepareThinLtoModule);
             }
             save_temp_bitcode(cgcx, &module, "thin-lto-after-import");
         }
@@ -780,11 +778,11 @@ pub(crate) fn optimize_thin_module(
         // little differently.
         {
             info!("running thin lto passes over {}", module.name);
-            run_pass_manager(cgcx, dcx, &mut module, true)?;
+            run_pass_manager(cgcx, dcx, &mut module, true);
             save_temp_bitcode(cgcx, &module, "thin-lto-after-pm");
         }
     }
-    Ok(module)
+    module
 }
 
 /// Maps LLVM module identifiers to their corresponding LLVM LTO cache keys
@@ -850,9 +848,9 @@ pub(crate) fn parse_module<'a>(
     name: &CStr,
     data: &[u8],
     dcx: DiagCtxtHandle<'_>,
-) -> Result<&'a llvm::Module, FatalError> {
+) -> &'a llvm::Module {
     unsafe {
         llvm::LLVMRustParseBitcodeForLTO(cx, data.as_ptr(), data.len(), name.as_ptr())
-            .ok_or_else(|| write::llvm_err(dcx, LlvmError::ParseBitcode))
+            .unwrap_or_else(|| write::llvm_err(dcx, LlvmError::ParseBitcode))
     }
 }
diff --git a/compiler/rustc_codegen_llvm/src/back/write.rs b/compiler/rustc_codegen_llvm/src/back/write.rs
index 62998003ca114..31bbf7cc80c79 100644
--- a/compiler/rustc_codegen_llvm/src/back/write.rs
+++ b/compiler/rustc_codegen_llvm/src/back/write.rs
@@ -20,7 +20,7 @@ use rustc_codegen_ssa::traits::*;
 use rustc_codegen_ssa::{CompiledModule, ModuleCodegen, ModuleKind};
 use rustc_data_structures::profiling::SelfProfilerRef;
 use rustc_data_structures::small_c_str::SmallCStr;
-use rustc_errors::{DiagCtxtHandle, FatalError, Level};
+use rustc_errors::{DiagCtxtHandle, Level};
 use rustc_fs_util::{link_or_copy, path_to_c_string};
 use rustc_middle::ty::TyCtxt;
 use rustc_session::Session;
@@ -46,10 +46,10 @@ use crate::llvm::{self, DiagnosticInfo};
 use crate::type_::Type;
 use crate::{LlvmCodegenBackend, ModuleLlvm, base, common, llvm_util};
 
-pub(crate) fn llvm_err<'a>(dcx: DiagCtxtHandle<'_>, err: LlvmError<'a>) -> FatalError {
+pub(crate) fn llvm_err<'a>(dcx: DiagCtxtHandle<'_>, err: LlvmError<'a>) -> ! {
     match llvm::last_error() {
-        Some(llvm_err) => dcx.emit_almost_fatal(WithLlvmError(err, llvm_err)),
-        None => dcx.emit_almost_fatal(err),
+        Some(llvm_err) => dcx.emit_fatal(WithLlvmError(err, llvm_err)),
+        None => dcx.emit_fatal(err),
     }
 }
 
@@ -63,7 +63,7 @@ fn write_output_file<'ll>(
     file_type: llvm::FileType,
     self_profiler_ref: &SelfProfilerRef,
     verify_llvm_ir: bool,
-) -> Result<(), FatalError> {
+) {
     debug!("write_output_file output={:?} dwo_output={:?}", output, dwo_output);
     let output_c = path_to_c_string(output);
     let dwo_output_c;
@@ -100,7 +100,7 @@ fn write_output_file<'ll>(
         }
     }
 
-    result.into_result().map_err(|()| llvm_err(dcx, LlvmError::WriteOutput { path: output }))
+    result.into_result().unwrap_or_else(|()| llvm_err(dcx, LlvmError::WriteOutput { path: output }))
 }
 
 pub(crate) fn create_informational_target_machine(
@@ -112,7 +112,7 @@ pub(crate) fn create_informational_target_machine(
     // system/tcx is set up.
     let features = llvm_util::global_llvm_features(sess, false, only_base_features);
     target_machine_factory(sess, config::OptLevel::No, &features)(config)
-        .unwrap_or_else(|err| llvm_err(sess.dcx(), err).raise())
+        .unwrap_or_else(|err| llvm_err(sess.dcx(), err))
 }
 
 pub(crate) fn create_target_machine(tcx: TyCtxt<'_>, mod_name: &str) -> OwnedTargetMachine {
@@ -139,7 +139,7 @@ pub(crate) fn create_target_machine(tcx: TyCtxt<'_>, mod_name: &str) -> OwnedTar
         tcx.backend_optimization_level(()),
         tcx.global_backend_features(()),
     )(config)
-    .unwrap_or_else(|err| llvm_err(tcx.dcx(), err).raise())
+    .unwrap_or_else(|err| llvm_err(tcx.dcx(), err))
 }
 
 fn to_llvm_opt_settings(cfg: config::OptLevel) -> (llvm::CodeGenOptLevel, llvm::CodeGenOptSize) {
@@ -565,7 +565,7 @@ pub(crate) unsafe fn llvm_optimize(
     opt_level: config::OptLevel,
     opt_stage: llvm::OptStage,
     autodiff_stage: AutodiffStage,
-) -> Result<(), FatalError> {
+) {
     // Enzyme:
     // The whole point of compiler based AD is to differentiate optimized IR instead of unoptimized
     // source code. However, benchmarks show that optimizations increasing the code size
@@ -704,7 +704,7 @@ pub(crate) unsafe fn llvm_optimize(
             llvm_plugins.len(),
         )
     };
-    result.into_result().map_err(|()| llvm_err(dcx, LlvmError::RunLlvmPasses))
+    result.into_result().unwrap_or_else(|()| llvm_err(dcx, LlvmError::RunLlvmPasses))
 }
 
 // Unsafe due to LLVM calls.
@@ -713,7 +713,7 @@ pub(crate) fn optimize(
     dcx: DiagCtxtHandle<'_>,
     module: &mut ModuleCodegen<ModuleLlvm>,
     config: &ModuleConfig,
-) -> Result<(), FatalError> {
+) {
     let _timer = cgcx.prof.generic_activity_with_arg("LLVM_module_optimize", &*module.name);
 
     let llcx = &*module.module_llvm.llcx;
@@ -765,7 +765,7 @@ pub(crate) fn optimize(
                 opt_stage,
                 autodiff_stage,
             )
-        }?;
+        };
         if let Some(thin_lto_buffer) = thin_lto_buffer {
             let thin_lto_buffer = unsafe { ThinBuffer::from_raw_ptr(thin_lto_buffer) };
             module.thin_lto_buffer = Some(thin_lto_buffer.data().to_vec());
@@ -793,14 +793,13 @@ pub(crate) fn optimize(
             }
         }
     }
-    Ok(())
 }
 
 pub(crate) fn codegen(
     cgcx: &CodegenContext<LlvmCodegenBackend>,
     module: ModuleCodegen<ModuleLlvm>,
     config: &ModuleConfig,
-) -> Result<CompiledModule, FatalError> {
+) -> CompiledModule {
     let dcx = cgcx.create_dcx();
     let dcx = dcx.handle();
 
@@ -909,7 +908,9 @@ pub(crate) fn codegen(
                 record_artifact_size(&cgcx.prof, "llvm_ir", &out);
             }
 
-            result.into_result().map_err(|()| llvm_err(dcx, LlvmError::WriteIr { path: &out }))?;
+            result
+                .into_result()
+                .unwrap_or_else(|()| llvm_err(dcx, LlvmError::WriteIr { path: &out }));
         }
 
         if config.emit_asm {
@@ -940,7 +941,7 @@ pub(crate) fn codegen(
                 llvm::FileType::AssemblyFile,
                 &cgcx.prof,
                 config.verify_llvm_ir,
-            )?;
+            );
         }
 
         match config.emit_obj {
@@ -976,7 +977,7 @@ pub(crate) fn codegen(
                     llvm::FileType::ObjectFile,
                     &cgcx.prof,
                     config.verify_llvm_ir,
-                )?;
+                );
             }
 
             EmitObj::Bitcode => {
@@ -1009,7 +1010,7 @@ pub(crate) fn codegen(
         && cgcx.target_can_use_split_dwarf
         && cgcx.split_debuginfo != SplitDebuginfo::Off
         && cgcx.split_dwarf_kind == SplitDwarfKind::Split;
-    Ok(module.into_compiled_module(
+    module.into_compiled_module(
         config.emit_obj != EmitObj::None,
         dwarf_object_emitted,
         config.emit_bc,
@@ -1017,7 +1018,7 @@ pub(crate) fn codegen(
         config.emit_ir,
         &cgcx.output_filenames,
         cgcx.invocation_temp.as_deref(),
-    ))
+    )
 }
 
 fn create_section_with_flags_asm(section_name: &str, section_flags: &str, data: &[u8]) -> Vec<u8> {
diff --git a/compiler/rustc_codegen_llvm/src/lib.rs b/compiler/rustc_codegen_llvm/src/lib.rs
index 0fcf31d799308..628cb34fd9e46 100644
--- a/compiler/rustc_codegen_llvm/src/lib.rs
+++ b/compiler/rustc_codegen_llvm/src/lib.rs
@@ -37,7 +37,7 @@ use rustc_codegen_ssa::back::write::{
 use rustc_codegen_ssa::traits::*;
 use rustc_codegen_ssa::{CodegenResults, CompiledModule, ModuleCodegen, TargetConfig};
 use rustc_data_structures::fx::FxIndexMap;
-use rustc_errors::{DiagCtxtHandle, FatalError};
+use rustc_errors::DiagCtxtHandle;
 use rustc_metadata::EncodedMetadata;
 use rustc_middle::dep_graph::{WorkProduct, WorkProductId};
 use rustc_middle::ty::TyCtxt;
@@ -165,15 +165,15 @@ impl WriteBackendMethods for LlvmCodegenBackend {
         exported_symbols_for_lto: &[String],
         each_linked_rlib_for_lto: &[PathBuf],
         modules: Vec<FatLtoInput<Self>>,
-    ) -> Result<ModuleCodegen<Self::Module>, FatalError> {
+    ) -> ModuleCodegen<Self::Module> {
         let mut module =
-            back::lto::run_fat(cgcx, exported_symbols_for_lto, each_linked_rlib_for_lto, modules)?;
+            back::lto::run_fat(cgcx, exported_symbols_for_lto, each_linked_rlib_for_lto, modules);
 
         let dcx = cgcx.create_dcx();
         let dcx = dcx.handle();
-        back::lto::run_pass_manager(cgcx, dcx, &mut module, false)?;
+        back::lto::run_pass_manager(cgcx, dcx, &mut module, false);
 
-        Ok(module)
+        module
     }
     fn run_thin_lto(
         cgcx: &CodegenContext<Self>,
@@ -181,7 +181,7 @@ impl WriteBackendMethods for LlvmCodegenBackend {
         each_linked_rlib_for_lto: &[PathBuf],
         modules: Vec<(String, Self::ThinBuffer)>,
         cached_modules: Vec<(SerializedModule<Self::ModuleBuffer>, WorkProduct)>,
-    ) -> Result<(Vec<ThinModule<Self>>, Vec<WorkProduct>), FatalError> {
+    ) -> (Vec<ThinModule<Self>>, Vec<WorkProduct>) {
         back::lto::run_thin(
             cgcx,
             exported_symbols_for_lto,
@@ -195,20 +195,20 @@ impl WriteBackendMethods for LlvmCodegenBackend {
         dcx: DiagCtxtHandle<'_>,
         module: &mut ModuleCodegen<Self::Module>,
         config: &ModuleConfig,
-    ) -> Result<(), FatalError> {
+    ) {
         back::write::optimize(cgcx, dcx, module, config)
     }
     fn optimize_thin(
         cgcx: &CodegenContext<Self>,
         thin: ThinModule<Self>,
-    ) -> Result<ModuleCodegen<Self::Module>, FatalError> {
+    ) -> ModuleCodegen<Self::Module> {
         back::lto::optimize_thin_module(thin, cgcx)
     }
     fn codegen(
         cgcx: &CodegenContext<Self>,
         module: ModuleCodegen<Self::Module>,
         config: &ModuleConfig,
-    ) -> Result<CompiledModule, FatalError> {
+    ) -> CompiledModule {
         back::write::codegen(cgcx, module, config)
     }
     fn prepare_thin(
@@ -407,12 +407,12 @@ impl ModuleLlvm {
         cgcx: &CodegenContext<LlvmCodegenBackend>,
         name: &str,
         dcx: DiagCtxtHandle<'_>,
-    ) -> Result<OwnedTargetMachine, FatalError> {
+    ) -> OwnedTargetMachine {
         let tm_factory_config = TargetMachineFactoryConfig::new(cgcx, name);
         match (cgcx.tm_factory)(tm_factory_config) {
-            Ok(m) => Ok(m),
+            Ok(m) => m,
             Err(e) => {
-                return Err(dcx.emit_almost_fatal(ParseTargetMachineConfig(e)));
+                dcx.emit_fatal(ParseTargetMachineConfig(e));
             }
         }
     }
@@ -422,13 +422,13 @@ impl ModuleLlvm {
         name: &CStr,
         buffer: &[u8],
         dcx: DiagCtxtHandle<'_>,
-    ) -> Result<Self, FatalError> {
+    ) -> Self {
         unsafe {
             let llcx = llvm::LLVMRustContextCreate(cgcx.fewer_names);
-            let llmod_raw = back::lto::parse_module(llcx, name, buffer, dcx)?;
-            let tm = ModuleLlvm::tm_from_cgcx(cgcx, name.to_str().unwrap(), dcx)?;
+            let llmod_raw = back::lto::parse_module(llcx, name, buffer, dcx);
+            let tm = ModuleLlvm::tm_from_cgcx(cgcx, name.to_str().unwrap(), dcx);
 
-            Ok(ModuleLlvm { llmod_raw, llcx, tm: ManuallyDrop::new(tm) })
+            ModuleLlvm { llmod_raw, llcx, tm: ManuallyDrop::new(tm) }
         }
     }
 
diff --git a/compiler/rustc_codegen_ssa/src/back/write.rs b/compiler/rustc_codegen_ssa/src/back/write.rs
index 26d089a117108..9f22859ba81ca 100644
--- a/compiler/rustc_codegen_ssa/src/back/write.rs
+++ b/compiler/rustc_codegen_ssa/src/back/write.rs
@@ -1,5 +1,6 @@
 use std::assert_matches::assert_matches;
 use std::marker::PhantomData;
+use std::panic::AssertUnwindSafe;
 use std::path::{Path, PathBuf};
 use std::sync::Arc;
 use std::sync::mpsc::{Receiver, Sender, channel};
@@ -14,7 +15,7 @@ use rustc_data_structures::profiling::{SelfProfilerRef, VerboseTimingGuard};
 use rustc_errors::emitter::Emitter;
 use rustc_errors::translation::Translator;
 use rustc_errors::{
-    Diag, DiagArgMap, DiagCtxt, DiagMessage, ErrCode, FatalError, Level, MultiSpan, Style,
+    Diag, DiagArgMap, DiagCtxt, DiagMessage, ErrCode, FatalErrorMarker, Level, MultiSpan, Style,
     Suggestions,
 };
 use rustc_fs_util::link_or_copy;
@@ -395,8 +396,7 @@ fn generate_thin_lto_work<B: ExtraBackendMethods>(
         each_linked_rlib_for_lto,
         needs_thin_lto,
         import_only_modules,
-    )
-    .unwrap_or_else(|e| e.raise());
+    );
     lto_modules
         .into_iter()
         .map(|module| {
@@ -844,11 +844,11 @@ fn execute_optimize_work_item<B: ExtraBackendMethods>(
     cgcx: &CodegenContext<B>,
     mut module: ModuleCodegen<B::Module>,
     module_config: &ModuleConfig,
-) -> Result<WorkItemResult<B>, FatalError> {
+) -> WorkItemResult<B> {
     let dcx = cgcx.create_dcx();
     let dcx = dcx.handle();
 
-    B::optimize(cgcx, dcx, &mut module, module_config)?;
+    B::optimize(cgcx, dcx, &mut module, module_config);
 
     // After we've done the initial round of optimizations we need to
     // decide whether to synchronously codegen this module or ship it
@@ -868,8 +868,8 @@ fn execute_optimize_work_item<B: ExtraBackendMethods>(
 
     match lto_type {
         ComputedLtoType::No => {
-            let module = B::codegen(cgcx, module, module_config)?;
-            Ok(WorkItemResult::Finished(module))
+            let module = B::codegen(cgcx, module, module_config);
+            WorkItemResult::Finished(module)
         }
         ComputedLtoType::Thin => {
             let (name, thin_buffer) = B::prepare_thin(module, false);
@@ -878,7 +878,7 @@ fn execute_optimize_work_item<B: ExtraBackendMethods>(
                     panic!("Error writing pre-lto-bitcode file `{}`: {}", path.display(), e);
                 });
             }
-            Ok(WorkItemResult::NeedsThinLto(name, thin_buffer))
+            WorkItemResult::NeedsThinLto(name, thin_buffer)
         }
         ComputedLtoType::Fat => match bitcode {
             Some(path) => {
@@ -886,12 +886,12 @@ fn execute_optimize_work_item<B: ExtraBackendMethods>(
                 fs::write(&path, buffer.data()).unwrap_or_else(|e| {
                     panic!("Error writing pre-lto-bitcode file `{}`: {}", path.display(), e);
                 });
-                Ok(WorkItemResult::NeedsFatLto(FatLtoInput::Serialized {
+                WorkItemResult::NeedsFatLto(FatLtoInput::Serialized {
                     name,
                     buffer: SerializedModule::Local(buffer),
-                }))
+                })
             }
-            None => Ok(WorkItemResult::NeedsFatLto(FatLtoInput::InMemory(module))),
+            None => WorkItemResult::NeedsFatLto(FatLtoInput::InMemory(module)),
         },
     }
 }
@@ -987,7 +987,7 @@ fn execute_fat_lto_work_item<B: ExtraBackendMethods>(
     mut needs_fat_lto: Vec<FatLtoInput<B>>,
     import_only_modules: Vec<(SerializedModule<B::ModuleBuffer>, WorkProduct)>,
     module_config: &ModuleConfig,
-) -> Result<WorkItemResult<B>, FatalError> {
+) -> WorkItemResult<B> {
     for (module, wp) in import_only_modules {
         needs_fat_lto.push(FatLtoInput::Serialized { name: wp.cgu_name, buffer: module })
     }
@@ -997,19 +997,19 @@ fn execute_fat_lto_work_item<B: ExtraBackendMethods>(
         exported_symbols_for_lto,
         each_linked_rlib_for_lto,
         needs_fat_lto,
-    )?;
-    let module = B::codegen(cgcx, module, module_config)?;
-    Ok(WorkItemResult::Finished(module))
+    );
+    let module = B::codegen(cgcx, module, module_config);
+    WorkItemResult::Finished(module)
 }
 
 fn execute_thin_lto_work_item<B: ExtraBackendMethods>(
     cgcx: &CodegenContext<B>,
     module: lto::ThinModule<B>,
     module_config: &ModuleConfig,
-) -> Result<WorkItemResult<B>, FatalError> {
-    let module = B::optimize_thin(cgcx, module)?;
-    let module = B::codegen(cgcx, module, module_config)?;
-    Ok(WorkItemResult::Finished(module))
+) -> WorkItemResult<B> {
+    let module = B::optimize_thin(cgcx, module);
+    let module = B::codegen(cgcx, module, module_config);
+    WorkItemResult::Finished(module)
 }
 
 /// Messages sent to the coordinator.
@@ -1722,37 +1722,10 @@ fn spawn_work<'a, B: ExtraBackendMethods>(
     let cgcx = cgcx.clone();
 
     B::spawn_named_thread(cgcx.time_trace, work.short_description(), move || {
-        // Set up a destructor which will fire off a message that we're done as
-        // we exit.
-        struct Bomb<B: ExtraBackendMethods> {
-            coordinator_send: Sender<Message<B>>,
-            result: Option<Result<WorkItemResult<B>, FatalError>>,
-        }
-        impl<B: ExtraBackendMethods> Drop for Bomb<B> {
-            fn drop(&mut self) {
-                let msg = match self.result.take() {
-                    Some(Ok(result)) => Message::WorkItem::<B> { result: Ok(result) },
-                    Some(Err(FatalError)) => {
-                        Message::WorkItem::<B> { result: Err(Some(WorkerFatalError)) }
-                    }
-                    None => Message::WorkItem::<B> { result: Err(None) },
-                };
-                drop(self.coordinator_send.send(msg));
-            }
-        }
-
-        let mut bomb = Bomb::<B> { coordinator_send, result: None };
-
-        // Execute the work itself, and if it finishes successfully then flag
-        // ourselves as a success as well.
-        //
-        // Note that we ignore any `FatalError` coming out of `execute_work_item`,
-        // as a diagnostic was already sent off to the main thread - just
-        // surface that there was an error in this worker.
-        bomb.result = {
+        let result = std::panic::catch_unwind(AssertUnwindSafe(|| {
             let module_config = cgcx.config(work.module_kind());
 
-            Some(match work {
+            match work {
                 WorkItem::Optimize(m) => {
                     let _timer =
                         cgcx.prof.generic_activity_with_arg("codegen_module_optimize", &*m.name);
@@ -1763,7 +1736,7 @@ fn spawn_work<'a, B: ExtraBackendMethods>(
                         "codegen_copy_artifacts_from_incr_cache",
                         &*m.name,
                     );
-                    Ok(execute_copy_from_cache_work_item(&cgcx, m, module_config))
+                    execute_copy_from_cache_work_item(&cgcx, m, module_config)
                 }
                 WorkItem::FatLto {
                     exported_symbols_for_lto,
@@ -1788,8 +1761,22 @@ fn spawn_work<'a, B: ExtraBackendMethods>(
                         cgcx.prof.generic_activity_with_arg("codegen_module_perform_lto", m.name());
                     execute_thin_lto_work_item(&cgcx, m, module_config)
                 }
-            })
+            }
+        }));
+
+        let msg = match result {
+            Ok(result) => Message::WorkItem::<B> { result: Ok(result) },
+
+            // We ignore any `FatalError` coming out of `execute_work_item`, as a
+            // diagnostic was already sent off to the main thread - just surface
+            // that there was an error in this worker.
+            Err(err) if err.is::<FatalErrorMarker>() => {
+                Message::WorkItem::<B> { result: Err(Some(WorkerFatalError)) }
+            }
+
+            Err(_) => Message::WorkItem::<B> { result: Err(None) },
         };
+        drop(coordinator_send.send(msg));
     })
     .expect("failed to spawn work thread");
 }
diff --git a/compiler/rustc_codegen_ssa/src/traits/write.rs b/compiler/rustc_codegen_ssa/src/traits/write.rs
index c29ad90735b7b..cc7c4e46d7bba 100644
--- a/compiler/rustc_codegen_ssa/src/traits/write.rs
+++ b/compiler/rustc_codegen_ssa/src/traits/write.rs
@@ -1,6 +1,6 @@
 use std::path::PathBuf;
 
-use rustc_errors::{DiagCtxtHandle, FatalError};
+use rustc_errors::DiagCtxtHandle;
 use rustc_middle::dep_graph::WorkProduct;
 
 use crate::back::lto::{SerializedModule, ThinModule};
@@ -22,7 +22,7 @@ pub trait WriteBackendMethods: Clone + 'static {
         exported_symbols_for_lto: &[String],
         each_linked_rlib_for_lto: &[PathBuf],
         modules: Vec<FatLtoInput<Self>>,
-    ) -> Result<ModuleCodegen<Self::Module>, FatalError>;
+    ) -> ModuleCodegen<Self::Module>;
     /// Performs thin LTO by performing necessary global analysis and returning two
     /// lists, one of the modules that need optimization and another for modules that
     /// can simply be copied over from the incr. comp. cache.
@@ -32,7 +32,7 @@ pub trait WriteBackendMethods: Clone + 'static {
         each_linked_rlib_for_lto: &[PathBuf],
         modules: Vec<(String, Self::ThinBuffer)>,
         cached_modules: Vec<(SerializedModule<Self::ModuleBuffer>, WorkProduct)>,
-    ) -> Result<(Vec<ThinModule<Self>>, Vec<WorkProduct>), FatalError>;
+    ) -> (Vec<ThinModule<Self>>, Vec<WorkProduct>);
     fn print_pass_timings(&self);
     fn print_statistics(&self);
     fn optimize(
@@ -40,16 +40,16 @@ pub trait WriteBackendMethods: Clone + 'static {
         dcx: DiagCtxtHandle<'_>,
         module: &mut ModuleCodegen<Self::Module>,
         config: &ModuleConfig,
-    ) -> Result<(), FatalError>;
+    );
     fn optimize_thin(
         cgcx: &CodegenContext<Self>,
         thin: ThinModule<Self>,
-    ) -> Result<ModuleCodegen<Self::Module>, FatalError>;
+    ) -> ModuleCodegen<Self::Module>;
     fn codegen(
         cgcx: &CodegenContext<Self>,
         module: ModuleCodegen<Self::Module>,
         config: &ModuleConfig,
-    ) -> Result<CompiledModule, FatalError>;
+    ) -> CompiledModule;
     fn prepare_thin(
         module: ModuleCodegen<Self::Module>,
         want_summary: bool,