diff --git a/src/lib.rs b/src/lib.rs
index fb02fe16f5..a4dfd7b1ab 100644
--- a/src/lib.rs
+++ b/src/lib.rs
@@ -592,6 +592,10 @@ impl Builder {
             output_vector.push("--sort-semantically".into());
         }
 
+        if self.options.merge_extern_blocks {
+            output_vector.push("--merge-extern-blocks".into());
+        }
+
         // Add clang arguments
 
         output_vector.push("--".into());
@@ -1481,7 +1485,7 @@ impl Builder {
         self
     }
 
-    /// If true, enables the sorting of the output in a predefined manner
+    /// If true, enables the sorting of the output in a predefined manner.
     ///
     /// TODO: Perhaps move the sorting order out into a config
     pub fn sort_semantically(mut self, doit: bool) -> Self {
@@ -1489,6 +1493,12 @@ impl Builder {
         self
     }
 
+    /// If true, merges extern blocks.
+    pub fn merge_extern_blocks(mut self, doit: bool) -> Self {
+        self.options.merge_extern_blocks = doit;
+        self
+    }
+
     /// Generate the Rust bindings using the options built up thus far.
     pub fn generate(mut self) -> Result<Bindings, BindgenError> {
         // Add any extra arguments from the environment to the clang command line.
@@ -2019,8 +2029,11 @@ struct BindgenOptions {
     /// Emit vtable functions.
     vtable_generation: bool,
 
-    /// Sort the code generation
+    /// Sort the code generation.
     sort_semantically: bool,
+
+    /// Deduplicate `extern` blocks.
+    merge_extern_blocks: bool,
 }
 
 /// TODO(emilio): This is sort of a lie (see the error message that results from
@@ -2031,7 +2044,7 @@ impl ::std::panic::UnwindSafe for BindgenOptions {}
 impl BindgenOptions {
     /// Whether any of the enabled options requires `syn`.
     fn require_syn(&self) -> bool {
-        self.sort_semantically
+        self.sort_semantically || self.merge_extern_blocks
     }
 
     fn build(&mut self) {
@@ -2175,6 +2188,7 @@ impl Default for BindgenOptions {
             force_explicit_padding: false,
             vtable_generation: false,
             sort_semantically: false,
+            merge_extern_blocks: false,
         }
     }
 }
@@ -2480,6 +2494,59 @@ impl Bindings {
                     .unwrap()
                     .1;
 
+            if options.merge_extern_blocks {
+                // Here we will store all the items after deduplication.
+                let mut items = Vec::new();
+
+                // Keep all the extern blocks in a different `Vec` for faster search.
+                let mut foreign_mods = Vec::<syn::ItemForeignMod>::new();
+                for item in syn_parsed_items {
+                    match item {
+                        syn::Item::ForeignMod(syn::ItemForeignMod {
+                            attrs,
+                            abi,
+                            brace_token,
+                            items: foreign_items,
+                        }) => {
+                            let mut exists = false;
+                            for foreign_mod in &mut foreign_mods {
+                                // Check if there is a extern block with the same ABI and
+                                // attributes.
+                                if foreign_mod.attrs == attrs &&
+                                    foreign_mod.abi == abi
+                                {
+                                    // Merge the items of the two blocks.
+                                    foreign_mod
+                                        .items
+                                        .extend_from_slice(&foreign_items);
+                                    exists = true;
+                                    break;
+                                }
+                            }
+                            // If no existing extern block had the same ABI and attributes, store
+                            // it.
+                            if !exists {
+                                foreign_mods.push(syn::ItemForeignMod {
+                                    attrs,
+                                    abi,
+                                    brace_token,
+                                    items: foreign_items,
+                                });
+                            }
+                        }
+                        // If the item is not an extern block, we don't have to do anything.
+                        _ => items.push(item),
+                    }
+                }
+
+                // Move all the extern blocks alongiside the rest of the items.
+                for foreign_mod in foreign_mods {
+                    items.push(syn::Item::ForeignMod(foreign_mod));
+                }
+
+                syn_parsed_items = items;
+            }
+
             if options.sort_semantically {
                 syn_parsed_items.sort_by_key(|item| match item {
                     syn::Item::Type(_) => 0,
diff --git a/src/options.rs b/src/options.rs
index 83da21f42f..8ae7cbe864 100644
--- a/src/options.rs
+++ b/src/options.rs
@@ -518,6 +518,9 @@ where
             Arg::new("sort-semantically")
                 .long("sort-semantically")
                 .help("Enables sorting of code generation in a predefined manner."),
+            Arg::new("merge-extern-blocks")
+                .long("merge-extern-blocks")
+                .help("Deduplicates extern blocks."),
             Arg::new("V")
                 .long("version")
                 .help("Prints the version, and exits"),
@@ -1007,5 +1010,9 @@ where
         builder = builder.sort_semantically(true);
     }
 
+    if matches.is_present("merge-extern-blocks") {
+        builder = builder.merge_extern_blocks(true);
+    }
+
     Ok((builder, output, verbose))
 }
diff --git a/tests/expectations/tests/merge-extern-blocks.rs b/tests/expectations/tests/merge-extern-blocks.rs
new file mode 100644
index 0000000000..66ceeff07f
--- /dev/null
+++ b/tests/expectations/tests/merge-extern-blocks.rs
@@ -0,0 +1,37 @@
+#![allow(
+    dead_code,
+    non_snake_case,
+    non_camel_case_types,
+    non_upper_case_globals
+)]
+
+#[repr(C)]
+#[derive(Debug, Default, Copy, Clone)]
+pub struct Point {
+    pub x: ::std::os::raw::c_int,
+}
+#[test]
+fn bindgen_test_layout_Point() {
+    const UNINIT: ::std::mem::MaybeUninit<Point> =
+        ::std::mem::MaybeUninit::uninit();
+    let ptr = UNINIT.as_ptr();
+    assert_eq!(
+        ::std::mem::size_of::<Point>(),
+        4usize,
+        concat!("Size of: ", stringify!(Point))
+    );
+    assert_eq!(
+        ::std::mem::align_of::<Point>(),
+        4usize,
+        concat!("Alignment of ", stringify!(Point))
+    );
+    assert_eq!(
+        unsafe { ::std::ptr::addr_of!((*ptr).x) as usize - ptr as usize },
+        0usize,
+        concat!("Offset of field: ", stringify!(Point), "::", stringify!(x))
+    );
+}
+extern "C" {
+    pub fn foo() -> ::std::os::raw::c_int;
+    pub fn bar() -> ::std::os::raw::c_int;
+}
diff --git a/tests/headers/merge-extern-blocks.h b/tests/headers/merge-extern-blocks.h
new file mode 100644
index 0000000000..1d46b7d4a3
--- /dev/null
+++ b/tests/headers/merge-extern-blocks.h
@@ -0,0 +1,6 @@
+// bindgen-flags: --merge-extern-blocks -- --target=x86_64-unknown-linux
+int foo();
+typedef struct Point {
+    int x;
+} Point;
+int bar();