diff --git a/fuzz/fuzz_targets/roundtrip.rs b/fuzz/fuzz_targets/roundtrip.rs
index 81467f6..66958f7 100644
--- a/fuzz/fuzz_targets/roundtrip.rs
+++ b/fuzz/fuzz_targets/roundtrip.rs
@@ -24,6 +24,7 @@ fuzz_target!(|module: wasm_smith::Module| {
             }
         }
     };
+    parsed_module.expand_all_funcs().unwrap();
     parsed_module.optimize();
     let _ = parsed_module.to_wasm_bytes();
 });
diff --git a/src/backend/mod.rs b/src/backend/mod.rs
index dd6da27..aac78f8 100644
--- a/src/backend/mod.rs
+++ b/src/backend/mod.rs
@@ -585,7 +585,7 @@ pub fn compile(module: &Module<'_>) -> anyhow::Result<Vec<u8>> {
     for (func, func_decl) in module.funcs.entries().skip(num_func_imports) {
         match func_decl {
             FuncDecl::Import(_) => anyhow::bail!("Import comes after func with body: {}", func),
-            FuncDecl::Body(sig, _) => {
+            FuncDecl::Lazy(sig, _) | FuncDecl::Body(sig, _) => {
                 funcs.function(sig.index() as u32);
             }
         }
@@ -689,21 +689,43 @@ pub fn compile(module: &Module<'_>) -> anyhow::Result<Vec<u8>> {
     into_mod.section(&elem);
 
     let mut code = wasm_encoder::CodeSection::new();
+    enum FuncOrRawBytes<'a> {
+        Func(wasm_encoder::Function),
+        Raw(&'a [u8]),
+    }
+
     let bodies = module
         .funcs
         .entries()
         .skip(num_func_imports)
         .collect::<Vec<_>>()
         .par_iter()
-        .map(|(func, func_decl)| -> Result<wasm_encoder::Function> {
-            let body = func_decl.body().unwrap();
-            log::debug!("Compiling {}", func);
-            WasmFuncBackend::new(body)?.compile()
+        .map(|(func, func_decl)| -> Result<FuncOrRawBytes> {
+            match func_decl {
+                FuncDecl::Lazy(_, reader) => {
+                    let data = &module.orig_bytes[reader.range()];
+                    Ok(FuncOrRawBytes::Raw(data))
+                }
+                FuncDecl::Body(_, body) => {
+                    log::debug!("Compiling {}", func);
+                    WasmFuncBackend::new(body)?
+                        .compile()
+                        .map(|f| FuncOrRawBytes::Func(f))
+                }
+                FuncDecl::Import(_) => unreachable!("Should have skipped imports"),
+            }
         })
-        .collect::<Result<Vec<_>>>()?;
+        .collect::<Result<Vec<FuncOrRawBytes<'_>>>>()?;
 
     for body in bodies {
-        code.function(&body);
+        match body {
+            FuncOrRawBytes::Func(f) => {
+                code.function(&f);
+            }
+            FuncOrRawBytes::Raw(bytes) => {
+                code.raw(bytes);
+            }
+        }
     }
     into_mod.section(&code);
 
diff --git a/src/bin/waffle-util.rs b/src/bin/waffle-util.rs
index 52a7f9a..32a49a6 100644
--- a/src/bin/waffle-util.rs
+++ b/src/bin/waffle-util.rs
@@ -41,6 +41,19 @@ enum Command {
     },
 }
 
+fn apply_options(opts: &Options, module: &mut Module) -> Result<()> {
+    if opts.basic_opts || opts.max_ssa {
+        module.expand_all_funcs()?;
+    }
+    if opts.basic_opts {
+        module.per_func_body(|body| body.optimize());
+    }
+    if opts.max_ssa {
+        module.per_func_body(|body| body.convert_to_max_ssa());
+    }
+    Ok(())
+}
+
 fn main() -> Result<()> {
     let opts = Options::from_args();
 
@@ -50,29 +63,19 @@ fn main() -> Result<()> {
     }
     let _ = logger.try_init();
 
-    match opts.command {
+    match &opts.command {
         Command::PrintIR { wasm } => {
             let bytes = std::fs::read(wasm)?;
             debug!("Loaded {} bytes of Wasm data", bytes.len());
             let mut module = Module::from_wasm_bytes(&bytes[..])?;
-            if opts.basic_opts {
-                module.optimize();
-            }
-            if opts.max_ssa {
-                module.convert_to_max_ssa();
-            }
+            apply_options(&opts, &mut module)?;
             println!("{}", module.display());
         }
         Command::RoundTrip { input, output } => {
             let bytes = std::fs::read(input)?;
             debug!("Loaded {} bytes of Wasm data", bytes.len());
             let mut module = Module::from_wasm_bytes(&bytes[..])?;
-            if opts.basic_opts {
-                module.optimize();
-            }
-            if opts.max_ssa {
-                module.convert_to_max_ssa();
-            }
+            apply_options(&opts, &mut module)?;
             let produced = module.to_wasm_bytes()?;
             std::fs::write(output, &produced[..])?;
         }
diff --git a/src/frontend.rs b/src/frontend.rs
index 8c9f262..b6c9754 100644
--- a/src/frontend.rs
+++ b/src/frontend.rs
@@ -146,10 +146,7 @@ fn handle_payload<'a>(
             *next_func += 1;
 
             let my_sig = module.funcs[func_idx].sig();
-            let body = parse_body(module, my_sig, body)?;
-
-            let existing_body = module.funcs[func_idx].body_mut().unwrap();
-            *existing_body = body;
+            module.funcs[func_idx] = FuncDecl::Lazy(my_sig, body);
         }
         Payload::ExportSection(reader) => {
             for export in reader {
@@ -269,10 +266,10 @@ fn handle_payload<'a>(
     Ok(())
 }
 
-fn parse_body<'a>(
+pub(crate) fn parse_body<'a>(
     module: &'a Module,
     my_sig: Signature,
-    body: wasmparser::FunctionBody,
+    body: &mut wasmparser::FunctionBody,
 ) -> Result<FunctionBody> {
     let mut ret: FunctionBody = FunctionBody::default();
 
diff --git a/src/ir/display.rs b/src/ir/display.rs
index c998105..eb0284d 100644
--- a/src/ir/display.rs
+++ b/src/ir/display.rs
@@ -190,14 +190,10 @@ impl<'a> Display for ModuleDisplay<'a> {
             for seg in &memory_data.segments {
                 writeln!(
                     f,
-                    "    {} offset {}: [{}]",
+                    "    {} offset {}: # {} bytes",
                     memory,
                     seg.offset,
-                    seg.data
-                        .iter()
-                        .map(|&byte| format!("0x{:02x}", byte))
-                        .collect::<Vec<_>>()
-                        .join(", ")
+                    seg.data.len()
                 )?;
             }
         }
@@ -217,6 +213,10 @@ impl<'a> Display for ModuleDisplay<'a> {
                     writeln!(f, "  {}: {} = # {}", func, sig, sig_strs.get(&sig).unwrap())?;
                     writeln!(f, "{}", body.display("    "))?;
                 }
+                FuncDecl::Lazy(sig, reader) => {
+                    writeln!(f, "  {}: {} = # {}", func, sig, sig_strs.get(&sig).unwrap())?;
+                    writeln!(f, "  # raw bytes (length {})", reader.range().len())?;
+                }
                 FuncDecl::Import(sig) => {
                     writeln!(f, "  {}: {} # {}", func, sig, sig_strs.get(&sig).unwrap())?;
                 }
diff --git a/src/ir/func.rs b/src/ir/func.rs
index f1bcdfa..7d6df34 100644
--- a/src/ir/func.rs
+++ b/src/ir/func.rs
@@ -1,21 +1,54 @@
 use super::{Block, FunctionBodyDisplay, Local, Module, Signature, Type, Value, ValueDef};
 use crate::cfg::CFGInfo;
 use crate::entity::{EntityRef, EntityVec, PerEntity};
+use crate::frontend::parse_body;
+use anyhow::Result;
 
 #[derive(Clone, Debug)]
-pub enum FuncDecl {
+pub enum FuncDecl<'a> {
     Import(Signature),
+    Lazy(Signature, wasmparser::FunctionBody<'a>),
     Body(Signature, FunctionBody),
 }
 
-impl FuncDecl {
+impl<'a> FuncDecl<'a> {
     pub fn sig(&self) -> Signature {
         match self {
             FuncDecl::Import(sig) => *sig,
+            FuncDecl::Lazy(sig, ..) => *sig,
             FuncDecl::Body(sig, ..) => *sig,
         }
     }
 
+    pub fn parse(&mut self, module: &Module) -> Result<()> {
+        match self {
+            FuncDecl::Lazy(sig, body) => {
+                let body = parse_body(module, *sig, body)?;
+                *self = FuncDecl::Body(*sig, body);
+                Ok(())
+            }
+            _ => Ok(()),
+        }
+    }
+
+    pub fn optimize(&mut self) {
+        match self {
+            FuncDecl::Body(_, body) => {
+                body.optimize();
+            }
+            _ => {}
+        }
+    }
+
+    pub fn convert_to_max_ssa(&mut self) {
+        match self {
+            FuncDecl::Body(_, body) => {
+                body.convert_to_max_ssa();
+            }
+            _ => {}
+        }
+    }
+
     pub fn body(&self) -> Option<&FunctionBody> {
         match self {
             FuncDecl::Body(_, body) => Some(body),
@@ -78,6 +111,18 @@ impl FunctionBody {
         }
     }
 
+    pub fn optimize(&mut self) {
+        let cfg = crate::cfg::CFGInfo::new(self);
+        crate::passes::basic_opt::gvn(self, &cfg);
+        crate::passes::resolve_aliases::run(self);
+        crate::passes::empty_blocks::run(self);
+    }
+
+    pub fn convert_to_max_ssa(&mut self) {
+        let cfg = crate::cfg::CFGInfo::new(self);
+        crate::passes::maxssa::run(self, &cfg);
+    }
+
     pub fn add_block(&mut self) -> Block {
         let id = self.blocks.push(BlockDef::default());
         log::trace!("add_block: block {}", id);
@@ -94,6 +139,23 @@ impl FunctionBody {
         log::trace!("add_edge: from {} to {}", from, to);
     }
 
+    pub fn recompute_edges(&mut self) {
+        for block in self.blocks.values_mut() {
+            block.preds.clear();
+            block.succs.clear();
+            block.pos_in_succ_pred.clear();
+            block.pos_in_pred_succ.clear();
+        }
+
+        for block in 0..self.blocks.len() {
+            let block = Block::new(block);
+            let terminator = self.blocks[block].terminator.clone();
+            terminator.visit_successors(|succ| {
+                self.add_edge(block, succ);
+            });
+        }
+    }
+
     pub fn add_value(&mut self, value: ValueDef) -> Value {
         log::trace!("add_value: def {:?}", value);
         let value = self.values.push(value);
diff --git a/src/ir/module.rs b/src/ir/module.rs
index ead764c..077248c 100644
--- a/src/ir/module.rs
+++ b/src/ir/module.rs
@@ -1,5 +1,5 @@
 use super::{Func, FuncDecl, Global, Memory, ModuleDisplay, Signature, Table, Type};
-use crate::entity::EntityVec;
+use crate::entity::{EntityRef, EntityVec};
 use crate::ir::FunctionBody;
 use crate::{backend, frontend};
 use anyhow::Result;
@@ -7,7 +7,7 @@ use anyhow::Result;
 #[derive(Clone, Debug)]
 pub struct Module<'a> {
     pub orig_bytes: &'a [u8],
-    pub funcs: EntityVec<Func, FuncDecl>,
+    pub funcs: EntityVec<Func, FuncDecl<'a>>,
     pub signatures: EntityVec<Signature, SignatureData>,
     pub globals: EntityVec<Global, GlobalData>,
     pub tables: EntityVec<Table, TableData>,
@@ -171,19 +171,22 @@ impl<'a> Module<'a> {
         }
     }
 
-    pub fn optimize(&mut self) {
-        self.per_func_body(|body| {
-            let cfg = crate::cfg::CFGInfo::new(body);
-            crate::passes::basic_opt::gvn(body, &cfg);
-            crate::passes::resolve_aliases::run(body);
-        });
+    pub fn expand_func<'b>(&'b mut self, id: Func) -> Result<&'b mut FuncDecl<'a>> {
+        if let FuncDecl::Lazy(..) = self.funcs[id] {
+            // End the borrow. This is cheap (a slice copy).
+            let mut func = self.funcs[id].clone();
+            func.parse(self)?;
+            self.funcs[id] = func;
+        }
+        Ok(&mut self.funcs[id])
     }
 
-    pub fn convert_to_max_ssa(&mut self) {
-        self.per_func_body(|body| {
-            let cfg = crate::cfg::CFGInfo::new(body);
-            crate::passes::maxssa::run(body, &cfg);
-        });
+    pub fn expand_all_funcs(&mut self) -> Result<()> {
+        for id in 0..self.funcs.len() {
+            let id = Func::new(id);
+            self.expand_func(id)?;
+        }
+        Ok(())
     }
 
     pub fn display<'b>(&'b self) -> ModuleDisplay<'b>
diff --git a/src/passes.rs b/src/passes.rs
index 39512ca..c001335 100644
--- a/src/passes.rs
+++ b/src/passes.rs
@@ -2,5 +2,6 @@
 
 pub mod basic_opt;
 pub mod dom_pass;
+pub mod empty_blocks;
 pub mod maxssa;
 pub mod resolve_aliases;
diff --git a/src/passes/empty_blocks.rs b/src/passes/empty_blocks.rs
new file mode 100644
index 0000000..1a7556b
--- /dev/null
+++ b/src/passes/empty_blocks.rs
@@ -0,0 +1,128 @@
+//! Pass to remove empty blocks.
+
+use crate::entity::EntityRef;
+use crate::ir::{Block, BlockTarget, FunctionBody, Terminator, Value, ValueDef};
+use std::borrow::Cow;
+use std::collections::HashSet;
+
+#[derive(Clone, Debug)]
+struct Forwarding {
+    to: Block,
+    args: Vec<ForwardingArg>,
+}
+
+#[derive(Clone, Copy, Debug)]
+enum ForwardingArg {
+    BlockParam(usize),
+    Value(Value),
+}
+
+impl Forwarding {
+    fn compose(a: &Forwarding, b: &Forwarding) -> Forwarding {
+        // `b` should be the target of `a.to`, but we can't assert
+        // that here. The composed target is thus `b.to`.
+        let to = b.to;
+
+        // For each arg in `b.args`, evaluate, replacing any
+        // `BlockParam` with the corresponding value from `a.args`.
+        let args = b
+            .args
+            .iter()
+            .map(|&arg| match arg {
+                ForwardingArg::BlockParam(idx) => a.args[idx].clone(),
+                ForwardingArg::Value(v) => ForwardingArg::Value(v),
+            })
+            .collect::<Vec<_>>();
+
+        Forwarding { to, args }
+    }
+}
+
+fn block_to_forwarding(body: &FunctionBody, block: Block) -> Option<Forwarding> {
+    // Must be empty except for terminator, and must have an
+    // unconditional-branch terminator.
+    if body.blocks[block].insts.len() > 0 {
+        return None;
+    }
+    let target = match &body.blocks[block].terminator {
+        &Terminator::Br { ref target } => target,
+        _ => return None,
+    };
+
+    // If conditions met, then gather ForwardingArgs.
+    let args = target
+        .args
+        .iter()
+        .map(|&arg| {
+            let arg = body.resolve_alias(arg);
+            match &body.values[arg] {
+                &ValueDef::BlockParam(param_block, index, _) if param_block == block => {
+                    ForwardingArg::BlockParam(index)
+                }
+                _ => ForwardingArg::Value(arg),
+            }
+        })
+        .collect::<Vec<_>>();
+
+    Some(Forwarding {
+        to: target.block,
+        args,
+    })
+}
+
+fn rewrite_target(forwardings: &[Option<Forwarding>], target: &BlockTarget) -> Option<BlockTarget> {
+    if !forwardings[target.block.index()].is_some() {
+        return None;
+    }
+
+    let mut forwarding = Cow::Borrowed(forwardings[target.block.index()].as_ref().unwrap());
+    let mut seen = HashSet::new();
+    while forwardings[forwarding.to.index()].is_some() && seen.insert(forwarding.to.index()) {
+        forwarding = Cow::Owned(Forwarding::compose(
+            &forwarding,
+            forwardings[forwarding.to.index()].as_ref().unwrap(),
+        ));
+    }
+
+    let args = forwarding
+        .args
+        .iter()
+        .map(|arg| match arg {
+            &ForwardingArg::Value(v) => v,
+            &ForwardingArg::BlockParam(idx) => target.args[idx],
+        })
+        .collect::<Vec<_>>();
+
+    Some(BlockTarget {
+        block: forwarding.to,
+        args,
+    })
+}
+
+pub fn run(body: &mut FunctionBody) {
+    // Identify empty blocks, and to where they should forward.
+    let forwardings = body
+        .blocks
+        .iter()
+        .map(|block| {
+            if block != body.entry {
+                block_to_forwarding(body, block)
+            } else {
+                None
+            }
+        })
+        .collect::<Vec<_>>();
+
+    // Rewrite every target according to a forwarding (or potentially
+    // a chain of composed forwardings).
+    for block_data in body.blocks.values_mut() {
+        block_data.terminator.update_targets(|target| {
+            if let Some(new_target) = rewrite_target(&forwardings[..], target) {
+                *target = new_target;
+            }
+        });
+    }
+
+    // Recompute preds/succs.
+    body.recompute_edges();
+}